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Preparation and Photo-thermal Properties of Thermo-sensitive Injectable Hydrogels Based on Chitosan and Au Nanoparticles
Jin-feng Zeng, Wen-di Yang, Dong-jian Shi, Xiao-jie Li, Ming-qing Chen
 doi: 10.11777/j.issn1000-3304.2018.18048
[Abstract](577) [FullText HTML](345) [PDF 1271KB](34)
Abstract:
Multiple injections of drugs are generally needed to continuously and effectively kill pathological cells during tumor therapeutic. However, this strategy might induce some side effects. Gold nanoparticles are one kind of photothermal agents that can convert the absorbed light energy into heat energy. This conversion could be used to photo-thermal therapy (PTT), which has property of multiple treatment for killing the tumor cells effectively and completely without other effects. Herein, this study aims to prepare injectable hydrogels with PTT property based on chitosan (CS), β-glycerophosphate (β-GP) and gold nanoparticles (Au NPs) for improving efficiency of anti-tumour. Firstly, CS bio-polymer stabilized Au NPs (CS-Au NPs) were directly reduced in situ by CS. Size of the CS-Au NPs could be controlled at 15 nm. Then, β-glycerophosphate (β-GP) was added into the CS-Au NPs. The mixture of CS-Au NPs and β-GP was sol state at room temperature, which could be injected into the tumor site. And then, at physiological temprature (37 °C), this sol could convert to gel (CGP/Au NPs) via the interactions between CS and β-GP, indicating that the (CGP/Au NPs) gel had the temperature sensitivity. Due to the surface plasmon resonance effect (SPR) of Au NPs, the (CGP/Au NPs) hydrogels showed an excellent photo-thermal property. The temperature of the (CGP/Au NPs) gel rised to above 45 °C and further to approximately 55 °C under Laser irradiation, with increasing amout of Au NPs. Moreover, the photo-thermal ability could be kept for several cycles with repeated laser irradiation. Because of easily fixing CGP hydrogels into biological tissue, Au NPs could be immobilized on the tumor site for a long time for multiple PTT. Thus, the strategies of muiliple drug-injection and blood circulation could be changed with the help of CGP hydrogels. Additionally, Au NPs were distributed evenly in the CGP hydrogels and the (CGP/Au NPs) hydrogels had good stability. Cell viability showed that the gels had excellent biocompatibility to the normal cells, and could kill remarkably the cancer cells with laser irradiation. Meanwhile, the prepared thermo-sensitive hydrogels had good biodegradability. Due to these characteristics, this (CGP/Au NPs) hydrogel might have the potential application to achieve " one time injection, multiple treatments” for tumor therapy.
Self-Assembly of Protein-Polymer Conjugate on Gold Surface Studied by Surface Plasmon Resonance Spectroscopy
Jin Li, Wen-wen Wang, Li-qiang Chu
 doi: 10.11777/j.issn1000-3304.2018.18063
[Abstract](356) [FullText HTML](182) [PDF 896KB](9)
Abstract:
Recently, protein-polymer conjugates, which combine protein molecules with one or more specific polymer chains at certain position, have attracted a great deal of attention due to their unique properties of both the proteins and the polymers. Therefore, the objective of this work is to study the self-assembly behavior of protein-polymer conjugates on a planar gold substrate, in which bovine serum albumin (BSA) is employed as the anchoring point for self-assembly process. We first prepare an initiator, 2-bromo-2-methylpropionic acid-2-aminooxy ethyl ester (ABM), which can be linked to the N-terminal of BSA modified by pyridoxal-5-phosphate (PLP), giving rise to a macroinitiator (i.e., BSA-Br). Then BSA-POEGMA conjugate is obtained by atom transfer radical polymerization (ATRP) using oligo(ethylene glycol) methacrylate (OEGMA) as monomer and the BSA-Br as macroinitiator, respectively. All products are characterized by Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS). FTIR and MALDI-TOF-MS results indicate that one POEGMA chain with a polymerization degree of 218 is coupled to the N-terminal of BSA. The adsorption behaviors of both the BSA and the BSA-POEGMA conjugate on gold surfaces are studied by using surface plasmon resonance spectroscopy (SPR). The data suggest that the BSA-POEGMA conjugate could be adsorbed to the gold substrate at the same way as the pure BSA molecule as expected, while the hydrophilic POEGMA chain is directed to the opposite of gold surface. At last, the adsorption behaviors of two model proteins (i.e., lysozyme, Lys and fibrinogen, Fib) on the BSA-POEGMA conjugate are also investigated. SPR data indicate that there is a decrease in Lys adsorption on the BSA-POEGMA compared to pure BSA layer. In contrast, Fib adsorption on the BSA-POEGMA conjugate increase slightly in comparison with that on pure BSA. The results clearly show the influence of POEGMA chain on the surface property of BSA molecule, which may be attributed to the water layer associated with the POEGMA chains.
Preparation and Multiple Responsiveness of Copolymers of PNIPAM Containing Azo Pyridine in Side Chain
Xiao-qiang Xue, Feng Qian, Wen-yan Huang, Hong-jun Yang, Qi-min Jiang, Lei Zhou, Bi-biao Jiang
 doi: 10.11777/j.issn1000-3304.2018.18002
[Abstract](217) [FullText HTML](191) [PDF 1565KB](29)
Abstract:
A novel azopyridine monomer was prepared by diazo coupling: 4-(4-pyridylazo) phenyl methacrylate (PAZO). PAZO was randomly copolymerized with N-isopropylacrylamide (NIPAM) and polyethylene glycol methyl ether methacrylate (EGMA) to obtain a multi-response terpolymer (P(NIPAM-co-PAZO-co-EGMA)). The structure of the polymer was characterized by 1H-NMR and gel permeation chromatography (GPC), and the responsiveness of the polymer to UV spectroscopy was studied. Under the acidic conditions, the trans absorption peak of azo pyridine is stable and the weakness is inhibited. Under alkaline conditions, the trans absorption peak is weak, and the cis absorption peak is enhanced and stable. The lowest phase transition temperature (LCST) of the polymer was 49 °C. The trans structure of azopyridine was changed to the cis structure by ultraviolet light irradiation. Before UV irradiation, the hydrodynamic radius of the polymer was 9.82 nm. After the UV illumination, the value became 11.07 nm, and increased by 1.25 nm, indicating that the polymer size was increased after UV illumination. The size of the polymer increased with the increased size of the azo pyridine structure, making the PNIPAM segment more sensitive to temperature and LCST decreased 2 °C to 47 °C. The LCST of polymer sites before introduction of CO2 was 49 °C, and that was changed to 62 °C after passing through CO2. Argon is bubbled through the polymer solution or the solution is left open at 60 °C for a period of time to evacuate the CO2. The LCST of the solution changes to 49 °C again. Before and after the introduction of CO2, there was no obvious change in the LCST point of the aqueous solution of PNIPAM, indicating that the carbonic acid did not affect the amine group on the PNIPAM group, but instead was protonated with the azopyridine group. The CO2 and Argon gasses were repeatedly introduced. The LCST of the polymer solution changed reversibly between 49 and 62 °C.
Synthesis and Properties of Polytetrahydrofuran-b-Polydimethylsilane-b-Polytetrahydrofuran Triblock Copolymer
Qi Zhang, Meng-juan Wei, Jin-rui Deng, Yi-xian Wu
 doi: 10.11777/j.issn1000-3304.2018.18032
[Abstract](348) [FullText HTML](201) [PDF 1655KB](25)
Abstract:
A series of polytetrahydrofuran (PTHF) and polydimethylsilane (PDMS) triblock copolymers (PTHF-b-PDMS-b-PTHF) have been synthesized via the combination of controlled termination of living PTHF chains (PTHF+) and ― NH2 functional groups along PDMS macromolecular backbone with the copolymerization efficiency of near 100%. PTHF living chains and PTHF+ were in situ prepared through living cationic opening polymerization of tetrahydrofuran (THF) with AllylBr/AgClO4 initiating system at 0 °C. The molecular weights of the PTHF chains were adjusted by mediating the molar ratio of the monomer to initiator. Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (1H-NMR) were used to characterize the microstructure of as-prepared triblock copolymers. Thermal properties of the triblock copolymers PTHF-b-PDMS-b-PTHF were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Additionally, polarization microscopy (POM) was employed to investigate the effect of number-average molecular weight (Mn,PTHF) of PTHF segments on the crystallization of the triblock copolymers. To have a further insight of the structures of the triblock copolymers, transmission electron microscopy (TEM) was also used to study their micromorphology. The antimicrobial activity of the material was characterized by determination of the E. coli inhibition zone. All characterization results aforementioned demonstrate that the well-defined triblock copolymers of PTHF-b-PDMS-b-PTHF with silver nanocomposites could be successfully prepared in situ with very high efficiency of ca. 95%. The crystallization of the triblock copolymers increased with increasing molecular weight of PTHF segments. Compared to the corresponding homopolymers of PTHF and PDMS, the thermal stability of the triblock copolymers was obviously improved. Moreover, the existence of amino groups (>N―H) in the macromolecular chains and a large number of ether bonds (―O―) from PTHF segments resulted in the formation of hydrogen bonds between the macro molecular chains of the triblock polymer, leading to the formation of physically cross-linked copolymer networks with more flexibility and better mechanical properties. Based on the strong hydrogen bonds, the obtained polymer networks show a pretty good self-healing performance at room temperature. The triblock copolymers were cut off at room temperature, then the cut section was self-healed for 24 h at room temperature, and the self-healed copolymers could be stretched to 1.5 times of the original length, which proved that the materials behaved good self-healing performance. Furthermore, the antimicrobial activity of the triblock copolymers was characterized by the inhibition zone method, and the diameter of inhibition zone of antibacterial was determined to be 13 mm, indicating a good antibacterial property. A novel nanocomposite, consisting of the triblock copolymer/silver, was synthesized in situ via controlled/living cationic ring-opening polymerization, and showed excellent properties resulted from PTHF, PDMS and Ag nano-particles, suggesting their potential applications in biological and medical fields.
Reversible-deactivation Radical Polymerization of Methyl Methacrylate Mediated by Carbodiimide Catalysts
Yan-An Wang, Xiao-Tao Zhang, Yan Shi, Zhi-Feng Fu, Wan-Tai Yang
 doi: 10.11777/j.issn1000-3304.2018.18046
[Abstract](252) [FullText HTML](165) [PDF 1347KB](14)
Abstract:
The reversible-deactivation radical polymerization (RDRP) of methyl methacrylate (MMA) was carried out utilizing an alkyl iodide in situ formed as initiator and dicyclohexylcarbodiimide (DCC) or N,N′-diisopropylcarbodiimide (DIC) as highly efficient organic catalysts for the first time. Firstly, the catalytic activity of the two catalysts was demonstrated and compared. The control of the polymerization by DCC was better than that by DIC under the same experimental conditions. Then the influence of the amount of catalyst DCC, the amount of traditional initiators and the type of solvents on the polymerization was investigated in detail. The results show that the addition of DCC or DIC catalyst can effectively reduce the polydispersity index (PDI = Mw/Mn), as compared with the reverse chain transfer polymerization (RITP). The catalytic performance is excellent with the ratio of [MMA]0:[I2]0:[ABVN]0:[DCC]0 = 200:1:1.7:4. The measured molecular weight by GPC is consistent with the theoretical molecular weight, and the molecular weight increases linearly with the increase in conversion rate. The molecular weight polydispersity index is small (PDI < 1.26). The polymerizations of MMA in different solvents were carried out. The induction period is shortened and the polymerization rate is increased with the increase of catalyst or initiator amount. The polymerizations have good control effect in toluene, benzene, tetrahydrofuran (THF), anisole. The structure and the iodine-end-capped structure of the obtained PMMA was demonstrated by 1H-NMR spectrum. The calculated Mn,NMR was in good agreement with Mn,GPC, and the fraction of iodine chain end of the PMMA chains was up to 97.5%, and the iodine terminus could be efficiently reactivated for chain extension. Last, the mechanism of the polymerization mediated by carbodiimide is discussed based on free radical trapping experiments and ultraviolet absorption. The high conversion of CP-I to CPo radical catalyzed by DIC and the complexation peak of I2/carbodiimide detected by ultraviolet absorption spectroscopy demonstrate that the polymerization catalyzed by carbodiimide proceeds according to the reversible complexation mediated polymerization mechanism.
Synthesis and Properties of Side-chain Type Poly(arylene ether ketone)s with Multiple Sulfonic Groups for Proton Exchange Membranes
Chen-yi Wang, Yuan-peng Zhou, Chang Xu, Xiao-yan Zhao, Jian Li, Qiang Ren
 doi: 10.11777/j.issn1000-3304.2018.18010
[Abstract](656) [FullText HTML](694) [PDF 787KB](52)
Abstract:
Aromatic sulfonated polymers are one class of very important functional polymers and can be used as proton exchange membranes (PEMs) for fuel cells. As one of the key components in fuel cells, they can provide ionic pathway for proton transport and act as a separator for the reactants. In order to improve their ionic conductivity and dimensional and chemical oxidation stabilities, this study reports a series of sulfonated poly(aryl ether ketone)s proton exchange membrane materials from their design of macromolecular structures. A series of novel poly(arylene ether ketone)s containing fluorene and pendant phenyl groups (4-PAEK-xx) were first synthesized through nucleophilic polycondensation reaction using 9,9-bis(3-phenyl-4-hydroxy) phenyl fluorene, 4,4′-(hexafluoroisopropylidene)diphenol and 1,4-bis(4-fluorobenzoyl)benzene as starting materials. They were then used to prepare a series of side-chain type poly(arylene ether ketone)s proton exchange membranes with multiple sulfonic groups (4-SPAEK-xx) by mild post-sulfonation reaction and solution casting. The structures and properties of these membranes were investigated. The results indicated that 4-SPAEK-xx membranes displayed moderate water absorption and low swelling ratio with the values in the range of 21% − 51.2% and 7.4% − 17.2% at 80 °C, respectively. These proton exchange membranes also exhibited good ionic conductivity with the values in the range of 115 − 171 mS/cm at 80 °C. The ionic conductivity of 4-PAEK-45 membrane (the ion exchange capacity of 2.12 mequiv/g) was even higher than that of the commercialized Nafion membrane. Moreover, these membranes had good thermal and mechanical property and chemical oxidative stability. Excellent comprehensive properties of 4-SPAEK- xx membranes were mainly ascribed to the incorporation of multiple pendant sulfonic groups and long fluorinated hydrophobic structures. The incorporation of multiple pendant sulfonic groups can not only effectively reduce the content of sulfonated units in the polymers, but also separate the ionic groups from the polymer backbones. Meanwhile, the incorporation of long fluorinated hydrophobic structures could further improve the dimensional and chemical oxidation stability of the obtained membranes. It is believed that this research would provide a valuable insight for the design and preparation of proton exchange polymer membranes of high-performance with aromatic sulfonated groups.
Effects of Fluorenyl Polyphosphazene Microspheres on the Flame Retardant Properties of Polybenzoxazine Resins
Chun-xia Zhao, Ling Zhao, Xiao-jia He, Hao-lan Gou, Yun-tao Li
 doi: 10.11777/j.issn1000-3304.2018.18042
[Abstract](285) [FullText HTML](119) [PDF 1754KB](11)
Abstract:
Fluorenyl polyphosphazene (PZFP) microspheres were facilely prepared through a one-step precipitation copolymerization of hexachlorocyclotriphosphazene (HCCP) and 4,4′-(9-fluorenylidene)diphenol under ultrasonic. PZFP microspheres were incorporated into polybenzoxazine resins to improve the flame properties of the polymers. The results of thermogravimetric analysis (TGA), cone calorimeter (CONE) and dynamic thermal mechanical analysis (DMA) showed that incorporation of PZFP microspheres enhanced the char residues amount of PBa during thermal degradation process, reduced the heat release rate (HRR), delayed the time to ignition (TTI) and increased the fire performance index (FPI) of PBa in fire. Interestingly, PBa/PZFP-10% showed the relatively best flame retardant properties among a series of PBa/PZFP composites with different PZFP contents. In comparison to pure PBa, the HRR value in the composite PBa/PZFP-10% was reduced to 214 kW·m−2 from 566 kW·m−2 for pure PBa, and FPI value was enhanced to 0.243 from 0.087. The glass transition temperature (Tg) and storage modules of PBa/PZFP-10% were increased slightly, with the introduction of 10% PZFP microspheres. The Tg of PBa and PBa/PZFP-10% was 222 and 226 °C, respectively. It is believed that PZFP microspheres offered PBa resins good flame retardant properties, without affecting the application temperature of PBa. The char residue analysis using scanning electron microscopy (SEM) suggested the formation of high-quality char layer with compact outer surfaces and polyphorous inner structure. The volatile products formed in the thermal degradation process of PBa and PBa/PZFP composites were detected by a TGA-Fourier transform infrared spectrometer (TGA-FTIR). The improved flame retardancy of PBa/PZFP composites was mainly attributed to a combination of the greatly increased melt viscosity of PBa and matrix fast swelling due to the pyrolytic gases. Additionally, PZFP microspheres was found to greatly reduce the amount of pyrolytic gases containing N―H and ―C=C=C― groups. Instead, it released phosphorous-containing species to achieve flame retardancy in the gas phase. PZFP microspheres contributed a synergistic condensed phase and gas phase flame retardant mechanism for PBa resins.
Thickening Kinetics of Monolayer Crystals of Low Molecular Weight Poly(ethylene oxide) Fractionson Mica Surfaces
Yi-xin Liu, Er-qiang Chen
 doi: 10.11777/j.issn1000-3304.2017.17333
[Abstract](416) [FullText HTML](236) [PDF 838KB](16)
Abstract:
The thickening of monolayer crystals of low molecular weight poly(ethylene oxide) (PEO) fractions on mica surface are in situ monitored by an atomic force microscopy (AFM) coupled with a hot stage. Two PEO fractions, with different molecular weights (HPEO2K, Mn = 2000; HPEO3K, Mn = 3000), have been examined. It is found that thickening domains continuously emerge when smooth once-folded-chain crystals are annealed isothermally below their melting temperature. A single thickening domain can grow in thickness and lateral size simutaneously. The growth of the thickness of the thickening domain follows a sigmoidal curve and depends significantly on the annealing temperature. It is found that the thickness of the thickening domain grows linearly with the logarithm of time. Such linear relation implies that its underlying mechanism should be nucleation and growth, as confirmed by a theoretical derivation of the thickness of the thickening domain as a function of time based on this mechanism. For each annealing temperature, a linear regression between the thickness of the thickening domain and the logarithm of time is performed and the obtained reciprocal of the slope linearly depends on the reciprocal of the annealing temperature. Then the surface free energy of the lateral surface of the folded-chain crystals can be inferred from the relation between the reciprocal of the slope and the annealing temperature. In this study, the value of the lateral surface free energy is found to be 1.25 and 1.22 kJ/mol for HPEO2K and HPEO3K, respectively. These values agree well with each other and also with reported values, which further validates our proposed mechanism. The lateral size of the thickening domain grows linearly with time as long as its thickeness approaches the extended-chain crystal. Such type of growth resembles the direct growth of the polymer crystals from the melt. However, its reltation between the growth rate and the annealing temperature is quite different from that of the growth of polymer crystals: the growth rate increases with the annealing temperature in the thickening case while it decreases with the crystallization temperature in the crystallization case. It indicates that there is an activation process rather than a nucleation process during thickening, which has been attributed to the chain sliding diffusion within the folded-chain crystals.
Preparation of PR/SiO2 Hybrid Phenolic Aerogel with Bi-component Gel Networks
Jian-jun Shi, Lei Kong, Xiao-biao Zuo, Deng-yao Liu, Jiao Yan, Zhi-hai Feng
 doi: 10.11777/j.issn1000-3304.2018.18054
[Abstract](340) [FullText HTML](173) [PDF 1032KB](20)
Abstract:
Hybrid phenolic resin/silica (PR/SiO2) hybrid aerogels with bicomponent and interpenetrating gel networks were prepared through co-gelating reaction by controlling Sol-Gel reaction and tuning gel time of hybrid solution. In this study, variations of the hybrid aerogels properties, including apparent density, linear shrinkage, pore texture, micromorphology, thermal stability and mechanical performance, with their silica aerogel contents were investigated. The results showed that apparent density of PR/SiO2 hybrid aerogels increased proportionally with increasing content of the silica aerogels. Compared to the pure organic phenolic (PR) aerogels, pore texture for PR/SiO2 hybrid aerogels were remarkably affected by the content of silica aerogels introduced by co-gelating reactions of phenolic resin and tetraethoxysilane (TEOS) monomers. Specific surface area of PR/SiO2 hybrid aerogels was improved and the average pore diameter decreased after incorporation of silica aerogels. As studied in the research, when the concentration of TEOS monomers increased to 1.50 mol/L, the average pore diameter of PR/SiO2 hybrid aerogel extremely decreased to 0.25 μm and the specific surface area increased from 24.6 m2/g for pure PR aerogel to 44 m2/g. Micromorphology detected by scanning electron microscopy (SEM) displayed that larger pores of hybrid aerogels were gradually filled by silica sol particles with increasing content of silica aerogels, which brought forth much more small openings and wider distribution for the pore diameter. Additionally, the skeleton’s strength and thermal stability of PR/SiO2 hybrid aerogels were efficiently enhanced after the incorporation of silica aerogels. As the concentration of TEOS monomers was 1 mol/L, the temperature corresponding to the maximum pyrolysis rate (Tmax) was improved from 539 °C to 602 °C, and the thermal decomposition zone of phenolic resin was evidently widened, which suggested that incorporation of silica aerogels effectively inhibited the pyrolysis of phenolic resins. The big promotion of thermal stability for PR/SiO2 hybrid aerogels was attributed to the thermal barrier and nano-dispersion of SiO2 sol particles in organic skeletons.
Study on Isothermal Crystallization Kinetics of Poly(ethylene oxide) Droplets by Fast Scanning Calorimetry
Rong Yang, Hong-mei Li, Jing Jiang, Dong-shan Zhou
 doi: 10.11777/j.issn1000-3304.2018.18024
[Abstract](137) [FullText HTML](101) [PDF 1013KB](5)
Abstract:
The isothermal crystallization kinetics of poly(ethylene oxide) (PEO) droplets was studied by fast scanning calorimetry (FSC) at a scanning rate up to 10000 K/s over a wide temperature range from its glass transition temperature to its melting temperature, and compared with that of PEO bulk sample. It was observed that the nucleation in PEO bulk sample during cooling is unavoidable even at a scanning rate of up to 50000 K/s because of numerous heterogeneity and the observation of an obvious cold crystallization peak in the subsequent heating curves. While the critical cooling rate is much slower when the sample was prepared by film dewetting and dispersed to several droplets smaller than 2 μm in diameter, and a fully amorphous sample could be obtained at a scanning rate of 10000 K/s. Isothermal crystallization of PEO bulk and that of droplets were studied in the time range from 10−2 s to 103 s at varied temperatures from 210 K to 310 K. The half crystallization time at each annealing temperature was calculated by fitting the enthalpy-time curve with a modified Avrami equation. It was found that the total crystallization rate of PEO droplets was systematically decreased by one magnitude in the whole temperature region. When the sample was dispersed into droplets of the size of several microns, the number of heterogeneity in each droplet was much less than that in the bulk or even heterogeneity-free in some droplets, with the average crystallization rate slowing down, especially in the low supercooling region, where heterogeneous nucleation is supposed to be dominant. The slowing down of crystallization rate was also observed at higher supercooling near Tg, where the homogeneous nucleation is considered to dominate the crystallization rate. Because of a slower homogeneous nucleation rate of PEO, the droplets sample with less heterogeneity mainly nucleated from homogeneous nucleation with a slower crystallization rate comparing to the unavoidable heterogeneous nucleation in bulk sample. The confinement of the droplet size may hinder the long-range diffusion of PEO chains and restricted the growth dimension under confinement, which could also be a reason for which a decrease in total crystallization rate of PEO droplets sample was observed.
Reactive Toughening Modification of 601 Epoxy Resin Using Poly(phthalazinone ether sulfone)s Bearing Pendant Carboxyl Groups
Hong-jun Guo, Xue Wang, Li-shuai Zong, Jian-fang Li, Jin-yan Wang, Gui-yang Li, Xi-gao Jian
 doi: 10.11777/j.issn1000-3304.2017.17286
[Abstract](238) [FullText HTML](169) [PDF 1563KB](9)
Abstract:
A series of poly(aryl ether sulfonephthalazinone)s (PPES-Ps) containing pendent carboxyl groups and N-heterocyclicphthalazinone units were derived from phenolphthalin (PPL) and 4-(3-chloro-4-hydroxylphenyl)(2H)-phthalazin-1-one (DHPZ) with 4,4′-dichlorodiphenyl sulfone (DCS) via " one-pot” solution polymerization. The structure of the resulting polymers was elaborately controlled by tailoring the feed ratio of the two diphenols to have a balance between the carboxyl content and the thermal resistance. As evidenced by NMR analysis, the structure of the corrsponding polymers along with the carboxyl content is consistent with those designed. PPES-Ps also exhibit high glass transition temperature (Tg > 260 °C) and excellent thermal stability as well as good solubility, mainly originating from the rigid, bulky, non-coplanar phthalazinone units. As the content of phthalazinone unit increases, both Tg and solubility demostrate an increasing trend. Furthermore, the copolymers with different contents of carboxyl groups are used to reactively toughen 601 epoxy resin. The mechanical and thermal properties of the obtained blending system are investigated in details. The results indicate that the pendant carboxyl groups in PPES-P can efficiently react with the epoxy groups of 601 resin during the thermal curing, leading to cross-linking networks by covalent bonding, which can not only improve the fracture toughness and flexural properties, but also maintain the high Tg of 601 epoxy resin. The impact strength of 601 epoxy resin, reactively toughened by PPES-P13 derived from PPL/DHPZ with the molar ratio of 1:3, is 43% higher than that of unmodified 601 resin. Meanwhile, the fracture of impact specimen shows a toughened fracture character, and no phase separation is observed on the crack surface, even with a high concent (15%) of PPES-P, which means that the reactive carboxyl moiety could enhance the compatibility between the high rigid poly(aryl ether)s and the epoxy resins. The 601 resins, reactively modified with PPES-Ps toughening, are thus expected to be useful in multistage toughening of carbon fiber reinforced resin matrix composites.
Fabrication of Mesoporous Polymeric Micelles and Their Application in Hg2+ Detection
Yuan-yuan Ju, Guang-da Han, Yan Lu, Han-ying Zhao
 doi: 10.11777/j.issn1000-3304.2018.18009
[Abstract](435) [FullText HTML](149) [PDF 1106KB](29)
Abstract:
Amphiphilic macromolecular brushes with pH-responsiveness and reduction responsiveness were synthesized by reversible addition-fragmentation chain transfer polymerization and atom transfer radical polymerization. The side chains of the brush polymers were covalently connected to the backbones through redox-responsive disulfide bonds. The structure, molecular weight and molecular weight distribution of the brush polymers were characterized by 1H-NMR and gel permeation chromatography. At pH = 10.0, the amphiphilic brush polymers self-assembled into multi-component micelles with POEGMA shells and PtBMA/PDMAEMA cores. In the cores, the two hydrophobic blocks segregated into distinct domains due to their incompatibility, and the hydrophilic POEGMA blocks formed the coronae to stabilize the structures. The PtBMA chains with larger volume percentage formed the continuous phases, while the PDMAEMA chains with smaller volume percentage formed the discontinuous phases. At pH = 4.0, protonated PDMAEMA chains were highly stretched and formed the coronae of the micelles. Excessive reductant was added into the micellar solution to reduce the disulfide bonds between PDMAEMA side chains and the backbones, and mesoporous polymeric micelles with thiol groups inside the pores were obtained. 1H-NMR results of multi-component micelles, before and after treatment with the reductant, indicated that the PDMAEMA side chains were removed completely. Transmission electron microscopy (TEM) and dynamic light scattering were used to characterize the morphology and the size of the micelles. Based on TEM results, the average size of the pores in the micelles was about 2 nm, which was consistent with the average size of the PDMAEMA discontinuous phases. After the cleavage of the disulfide bonds and the removal of PDMAEMA chains from the micelles, thiol groups were produced on the walls of the pores. The thiol groups can be used as reducing agent and stabilizer in the in situ synthesis of gold nanoparticles. By thiol-bromine reactions, mesoporous micelles with polythiophene derivatives inside the pores were synthesized. The micelles showed high sensitivity and excellent selectivity for Hg2+.
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Molecular Topology Effects in Self-assembly of Giant Surfactants
Wen Tang, Kan Yue, Stephen Z. D. Cheng
2018, 0(8): 959-972.   doi: 10.11777/j.issn1000-3304.2018.18102
[Abstract](427) [FullText HTML](247) [PDF 0KB](2)
Abstract:
Self-assembly of block copolymers, which are composed of covalently connected incompatible polymer chains, can result in various ordered structures at the nanometer scale. This phenomenon, widely known as the microphase separation of block copolymers, may provide a technological platform for the development of next-generation nanopatterning techniques based on the " top-down” strategy. During the past decade, a unique class of novel amphiphilic macromolecules termed as giant surfactants have been reported, which are constructed from selected building blocks of cluster-like molecules having three-dimensional rigid conformations and nanometer sizes. By combining different " click-type” reactions, a highly efficient and modular synthetic method has been developed to prepare covalent conjugates of these molecular clusters and polymer chains. The resulting giant surfactants can be viewed as structural analogues of common block copolymers, and similarly, they also display interesting self-assembly behaviors both in solutions and in bulk. Herein, recent advances on the study of self-assembly of giant surfactants are summarized, with a particular emphasis on the molecular topology effects that can significantly change their self-assembly behaviors. As revealed by small angle X-ray scattering and transmission electron microscopy techniques, giant surfactants were able to self-assemble in bulk to form a series of highly ordered nanostructures with feature sizes below 10 nm or even 5 nm, with clearly shifted phase boundaries. More importantly, through rational molecular design to tune the molecular topology of giant surfactants, formation of some unusual nanostructures driven by molecular topological variations was achieved. Typical examples include several unconventional spherical phases, such as the Frank-Kasper A15 phase, the Frank-Kasper σ phase, and a quasicrystalline spherical phase, which were observed in multitailed giant surfactants, and a highly asymmetric lamellar phase formed by self-assembly of multiheaded giant surfactants. It is believed that these studies provide not only insights towards understanding the molecular topological effects in macromolecular self-assembly, but also experimental foundation for the development of block copolymer lithography that can afford nanostructures with sub-10-nm feature sizes.
Columnar Phase of Side-chain Liquid Crystalline Polymers Based on “Multi-chain Column”
Rui-ying Zhao, Xu-qiang Jiang, Jun-feng Zheng, Xiao-qing Liu, Yan-shuang Xu, Shuang Yang, Er-qiang Chen
2018, 0(8): 973-986.   doi: 10.11777/j.issn1000-3304.2018.18065
[Abstract](263) [FullText HTML](151) [PDF 0KB](6)
Abstract:
Side-chain liquid crystalline polymer (SCLCP) can form columnar liquid crystalline (LC) phases, in addition to the conventional nematic and smectic phase. For the SCLCP containing the discotic mesogenic group attached to the main-chain through a flexible spacer, the columnar phase relies on the assembly of the discotic mesogens. On the other hand, the SCLCP with extended conformation, such as mesogen-jacketed LC polymers and dendronized polymers, can exhibit the columnar phase based on the parallel packing of the cylindrical chains. In this case, " single chain column” is considered to be the building block of the columnar phase in general. Recently, our work on hemiphasmid SCLCP demonstrates that the " multi-chain column” is also important for the columnar phases of SCLCP. Hemiphasmid SCLCP possesses the hemiphasmid side-chain composed of a rod-like mesogen linked with a half-disk end group. It can readily self-organize into columnar phases with a pretty lager lattice parameter (e.g., 5 – 10 nm). It is found that the number of repeating units (Zrep) packed in a column stratum with a thickness of ~ 0.4 nm is surprisingly large. As an example, for the hexagonal columnar phase with the a parameter of ~ 6 nm, the value of Zrep is ~ 10. Squeezing a chain segment with 10 repeating units into the 0.4 nm-thick column stratum is physically unreasonable. The " unusual Zrep” indicates the existence of " multi-chain column” that consists of a bundle of chains (e.g., 4 – 5 chains) laterally associated together. We synthesized a series of hemiphasmid SCLCPs with different chemical structures. Various main-chains have been employed, including polystyrene, poly(methacrylate), polyacetylene, and polynorbornene. The hemiphasmid moieties can invoke different rod-like mesogens, and can be attached to the main-chain directly or via a flexible spacer. For all the samples obtained, we have verified that the " multi-chain column” is applicable. The formation of " multi-chain column” can be understood from the nano-segregation among the main-chain, the rod-like mesogen and the flexible tails. Theoretical analysis indicates that the " multi-chain column” is a structure of thermodynamic equilibrium. The number of chains in the column is dependent on the volume fraction of the rigid component of the SCLCP. We propose that the chains in the column can interlock and intertwine, resulting in the intra-column entanglement. This hypothesis is supported by the study of hemiphasmid side-chain polynorbornene, which illustrates that the intra-column entanglement can endow the polymer with properties of thermoplastic elastomer. Moreover, the polymer can further exhibit excellent multi-shape memory effect at high strain. We anticipate that the further study of the " multi-chain column”, which has been overlooked for years, will deepen our understanding of some fundamental issues of the structure and dynamics of polymers, and will also help to explore the new properties and applications of SCLCPs.
Peptides/Amphiphilic Peptides Based Silk Fibroin of Bombxy Mori and Their Self-assembly and Functionalization
Hong Chen, Zheng-zhong Shao
2018, 0(8): 987-996.   doi: 10.11777/j.issn1000-3304.2018.18083
[Abstract](209) [FullText HTML](152) [PDF 2141KB](35)
Abstract:
Given the unique properties and functions, such as bioactivity and good biocompatibility, the self-assembly of peptide, specially amphipathic peptide, and their applications have become the research focus in the fields of supermolecular chemistry as well as functional polymeric and biomedical materials. Generally, most of peptide building blocks are prepared from chemical synthesis such as solid phase peptide synthesis, or genetic engineering. Those " bottom up” methods may be suffered by time consuming and cost, which limit the practical application of assembly peptides materials. Degradation of natural proteins such as casein, corn protein and so on, provides us a convenient way to obtain the mixed peptides. However, most of researches about these mixtures are focused on their bio-functions or surfactant property. The usage of them as building blocks of assembly peptide is overlooked. Silk fibroin from Bombyx mori silkworm silk is with highly repetitive sequences, such as GAGAGY and GAGAGS, their different assembly properties and the relevant structures not only play an important role in the forming of animal silks and silk fibroin based materials, but also have crucial effect on their excellent comprehensive performance. According to the selectivity of different enzymes, there are enzymes which work on the Tyr-Gly or Ala-Gly peptide bone, respectively. Therefore, it provides us the opportunity to harvest the silk peptides with special sequence economically via degrading silk fibroin by those enzymes. We introduced in this paper the enzymatic degradation, a " top down” method on obtaining peptide with specific sequences from silk fibroin and investigated their assembly properties. In addition, we summarized the construction of functionalization amphiphilic peptides with one of those silk peptides (GAGAGAGY) as building block as well as their assembly and applications like the forming pH responsive peptide hydrogel, flexible thermochromism materials and unique peptide surfactant. Finally, we prospected the application of top down method on obtaining functional peptide building blocks as well as application of the silk peptide obtained by this way on construction functional peptides.
Injectable Thermogels Based on Block Copolymers of Appropriate Amphiphilicity
Shu-quan Cui, Lin Yu, Jian-dong Ding
2018, 0(8): 997-1015.   doi: 10.11777/j.issn1000-3304.2018.18084
[Abstract](123) [FullText HTML](84) [PDF 1503KB](2)
Abstract:
Some amphiphilic copolymers in water can undergo a reversible sol-gel transition upon heating. If the transition temperature lies between room temperature and body temperature, the aqueous system can be readily mixed with drugs or cells at room temperature, and the mixture is injectable; the injected formulation is physically gelled at body temperature, and the gelation is free of any chemical crosslinking. This affords an amazing biomaterial type, yet many questions are open in light of fundamental research and potential clinical applications. In particular, block copolymers composed of hydrophilic poly(ethylene glycol) (PEG) and some hydrophobic biodegradable polyesters such as poly(lactide-co-glycolide) (PLGA) are of great clinical potential, yet of very unclear physical crosslinking points. This feature article summarizes the corresponding extensive investigations in the authors’ group led by Ding at Fudan University for a decade. The Ding group has found the significant effects of the end groups of the copolymer, molar mass dispersity ÐM, and other molecular parameters on thermogellability, and revealed the corresponding rules of molecular design, based on their polymer chemistry studies. For instance, with increase in ÐM under either given number average or weight average molecule weight, the sol-gel transition temperature for some block copolymer aqueous systems could shift unidirectionally, which indicates that the effect of molecular weight distribution could not be interpreted simply from addition of the effects of molecular weight or ÐM affords an independent adjustable parameter. The Ding group has shed light on the mechanism of their thermogelling by putting forward the model of percolated micelle network to describe the internal structure of the physical hydrogel, and extended the range of the thermogellable molecular composition of the copolymers to a large extent by establishing a blend strategy, based on their polymer physics studies. The Ding group have also put forward many strategies for the clinical applications of the thermogels using animal models, including prevention of postoperative tissue adhesion, submucosal cushion for endoscopic submucosal dissection, sustained release carriers of antitumor drugs such as camptothecin derivatives, long-acting formulations of polypeptide drugs such as exenatide in treatment of type II diabetes, and tissue engineering of cartilage. The Ding group has also laid a material basis towards potential products of medical devices and drug carriers including the appropriate way of sterilization and improvement of the handling property of the synthesized polymers. The Ding group suggest some perspectives in the end of this feather article.
Hydrogen Bonding Interactions Mediated Self-assembly Structures of Multicomponent Block Copolymer Mixtures
Ruey-Chorng Lin, Shiao-Wei Kuo
2018, 0(8): 1016-1032.   doi: 10.11777/j.issn1000-3304.2018.18020
[Abstract](474) [FullText HTML](336) [PDF 2838KB](60)
Abstract:
Self-assembly from block copolymers is a bottom-up process, a relatively inexpensive and simple approach for the preparation of large-scale nano-patterns. This self-assembly from diblock copolymers is driven by the combination of repulsive and attractive interactions due to the covalent bond linkage. The intrinsic immiscibility or incompatibility among the A or B block segments possesses the repulsive force and then confines into nanoscaled domain through the microphase separation because of the attractive force from the covalent bond linkage of A and B block segments. In general, these diblock copolymers can form different well-defined nanostructures in the bulk state including alternative lamellae, bicontinuous double gyroid, hexagonally packed cylinder, and body-centered cubic (BCC) structures, depending on the relative volume fractions of the block copolymer segments, interaction parameters (χ), and degrees of polymerization (N). However, the preparation of block copolymers with controlled volume fraction would be complicated and time-consuming; thus the diblock copolymers (A-b-B) blending with their homopolymer or low-molecular-weight compound would be an easier method for preparing different self-assembled nanostructures. Therefore, self-assembly nanostructures of block copolymer mixtures through mediated hydrogen bonding interactions have attracted much interest in polymer science because of their potential applications in photonic, electronic and biomedical fields, which could offer the unique possibility to create new functional polymeric materials with tunable and responsive behaviors. In this review article, we describe the self-assembly nanostructure of the block copolymer mixtures including block copolymer/low molecular weight compound, block copolymer/homopolymer, and block copolymer/block copolymer mixtures in bulk and solution states by mediated hydrogen bonding strength. Mediated strength of hydrogen bonding in block copolymer blending with homopolymer or block copolymer could provide order-order phase transition from typical lamellar, double gyroid, cylinder, and BCC spherical structure, even various hierarchical self-assembly structures such as three-phase lamellae, core-shell cylinder, and cylinder in lamellae structures in bulk state. Furthermore, it also possesses the different micellar structures of block copolymer mixtures such as spheres, rods, vesicles, and even large compound micelles in solution state.
Progress in Self-assembly of Polymer-coated Au Nanoparticles
Jia-jing Zhou, Di Wu, De-rong Lu, Hong-wei Duan
2018, 0(8): 1033-1047.   doi: 10.11777/j.issn1000-3304.2018.18050
[Abstract](278) [FullText HTML](218) [PDF 1388KB](29)
Abstract:
Gold nanostructures with unique optical, electrical and catalytic properties have found widespread use in diverse fields ranging from optics and sensing to nanomedicine and catalysis. There is growing interest in self-assembly of gold nanostructures because their localized surface plasmon resonance undergoes strongly interparticle coupling in close proximity, leading to collective properties that are distinctively different from that of individual building blocks. Considerable progress has been made in tailored synthesis of gold nanostructures and surface-engineering approaches to introduce functional coatings on the nanostructures, giving rise to nanoscale building blocks with defined structural parameters and properties, which make them excellent model systems to study the self-assembly of nanoparticles driven by functiona coatings. Polymers, especially amphiphilic block copolymers, exhibit intrinsic self-assembly in solution and bulk phase. Accumulated evidence has demonstrated that both molecular structures of the polymers and self-assembly conditions have a key impact on the structures formed by self-assembly, producing a wide spectrum of structures such as spherical micelles, cylindrical micelles, lamellae, and vesicles. As such, polymer coatings, which are commonly explored to impart colloidal stability of nanostructures, have emerged as an intriguing class of functional coatings to direct their self-assembly. The ability to tailor the structural details of the polymer coatings such as molecular weight, graft density and amphiphilicity is key to achieve controlled morphology and functionality of the resultant plasmonic assemblies. In this review, we summarize current strategies for constructing well-defined Au nanoparticle building blocks including " one-pot synthesis”, " grafting to”, and " grafting from” strategies. Based on these methods, assemblies of polymer-decorated nanoparticles were designed and formed across multiple dimensions, which brings about potential applications resulting from emerging optical, electronic, and catalytic properties. A protypical example is surface-enhanced Raman scattering (SERS) which is greatly amplified in the interstitial space of the assemblies because of interparticle plasmonic coupling, providing a transduction mechanism for ultrasensitve detection. The ability of dissipating the energy of light irradiate through the combination of photothermal conversion and Mie-scattering makes it possible for the assemblies of Au nanoparticles to serve as imaging probes and therapeutic agents. Representative assemblies of Au nanoparticles, that have shown potentials for sensing and biomedicine, are highlighted in this review. We also emphasize the fundamental and technical challenges for precise control over polymer-guided self-assembly of gold nanoparticles. The combination of simulation and experiment open the avenue to a systematic understanding on the self-assembly of nanoparticles.
Further Expansions and Applications of the Principles and Methodology of Non-covalent Connected Micelles
Guo-song Chen, Ping Yao, Dao-yong Chen
2018, 0(8): 1048-1065.   doi: 10.11777/j.issn1000-3304.2018.18064
[Abstract](116) [FullText HTML](88) [PDF 1826KB](18)
Abstract:
At the end of the last century, Professor Jiang Ming et al. succeeded in fabricating regular nanostructures through localizing interactions in the systems of polymer complexes. Through continuous expansion and deepening of this principle and method, a new strategy of macromolecular self-assembly was established. This review summarizes recent developments and applications of non-covalently connected micelles (NCCMs), including: Introducing of new driving forces such as supramolecular interactions to drive the formation of NCCMs, providing the resultant NCCMs with new features and functions; Applying the principle to the self-assembly of biological macromolecules, thereby developing an entirely green route to self-assembly of macromolecules; Also, through localizing covalent crosslinking reaction of one block of a diblock copolymer, we realized micellization of the block copolymer in its common solvent induced by the crosslinking reaction, resulting in highly efficient fabrication of core-stabilized micelles as well as a new pathway for controlling the kinetics of polymer micellization, the structures and the properties of the polymeric micelles.
Single Polymer Chain Grafted Fe3O4 Composite Janus Nanoparticle
Jing-yun Jing, Xiao-hui Yao, Zhen-zhong Yang
2018, 0(8): 1066-1072.   doi: 10.11777/j.issn1000-3304.2018.17233
[Abstract](371) [FullText HTML](274) [PDF 887KB](53)
Abstract:
An amine group capped Fe3O4 nanoparticle (NP) (~ 10 nm) is derived after ligand exchange with a silane against the oleic acid capped Fe3O4 NP. Via the termination between the cationic end of a living polymer chain with the amine group onto the NP surface, polymer chains are covalently grafted onto the NP surface, forming the polymer/Fe3O4 composite NP. The number of the grafted living polymer chains is determined by the molecular weight of the polymer chains. When a sufficiently long polymer chain with hydrodynamic size larger than the NP diameter is used, the arisen steric repulsion enables only one polymer chain to graft onto the NP surface. The obtained composite NP displays a parachute structure due to the distribution of the grafting polymer chain on one side of the modified Fe3O4 NP surface. When a short polymer chain is used, many chains can graft onto the NP surface to form a core/shell like structure. For example, the single poly(4-vinylbenzyl chloride) chain grafted an amine group capped Fe3O4 composite Janus NP is amphiphilic, which can serve as a functional solid emulsifier that can easily emulsify water/toluene to obtain a stabilized emulsion. In analogy of a molecular surfactant, a self-assembled monolayer from the composite NPs is achieved by crosslinking the composite NPs at a water/oil interface. The Fe3O4 composite Janus NPs can be manipulated with a magnet. Accordingly, the stabilized emulsion droplets emulsified by the composite Janus NPs can be driven with a magnet. This report provides a simple method to massively synthesize Janus NPs at a high solid content. In addition, a huge family of functional Janus NPs will be derived after selective growth of functional species from either poly(4-vinylbenzyl chloride) or (and) the amine group capped side of the parent composite NP.
Assembly of Functional Ligands on the Surface of Magnetic Composite Microspheres Based on Gold and Thiol Interaction
Jia-xun Wan, Lu-yan Sun, Chang-chun Wang
2018, 0(8): 1073-1080.   doi: 10.11777/j.issn1000-3304.2018.17319
[Abstract](254) [FullText HTML](187) [PDF 894KB](38)
Abstract:
Multifunctional magnetic nano-carriers, with high saturation magnetization, high drug-loading and rapid response for external magnetic field, have been widely applied in biomedical fields, such as bioimaging, targeting therapy, diagnostics and so on. In this study, a new efficient way for superficial modification of magnetic composite microspheres based on strong interaction between gold nanoparticles and thiol compounds was explored. Using the distilled-precipitation polymerization technique, we firstly constructed magnetic composite microspheres, (MSP@P(MAA-Cy), with acid-dissolvable magnetic supraparticles (MSP) as the core and a redox-degradable poly(methylacrylic acid-co-N,N-bis(acryloyl)cystamine) (P(MAA-Cy) as the shell, gold nanoparticles (AuNP) with the size of 10 − 30 nm were then deposited onto the surface of the MSP@P(MAA-Cy) microspheres. Through control of the reaction parameters in the distilled-precipitation polymerization, uniform polymer shell with the thickness of 30 − 40 nm was obtained. In addition, the amount and the size of the AuNP particle on the surface of MSP@P(MAA-Cy) microspheres could be adjusted by manipulating the ratio of the raw materials and reaction parameters. With an increase in the feeding amount of gold precursor, i.e. the feeding molar ratio of HAuCl4 to sodium citrate dihydrate (keep constant in all recipes) changed from 1:20 to 1:5, the particle size of the AuNP increased. Meanwhile, prolonging reaction time also could increase the density and particle szie of the AuNP. Due to the strong interaction between the thiol-modified fluorescent ligands and gold nanoparticles on the surface of MSP@P(MAA-Cy)-AuNP, single or dual fluorescent ligands (FA-PEG-SH and Rho-PEG-SH) could be easily assembled onto the surface of the magnetic polymer composite microspheres by one-step reaction, and the amount of the fluorescent ligands regulated by a convenient and fast way, which should give a new stratagy for onsite-assembly of functional ligands on the surface of magnetic composite microspheres without any post-treatment for personalized targeting cancer therapy.
Fabrication of Mesoporous Polymeric Micelles and Their Application in Hg2+ Detection
Yuan-yuan Ju, Guang-da Han, Yan Lu, Han-ying Zhao
2018, 0(8): 1081-1088.   doi: 10.11777/j.issn1000-3304.2018.18009
[Abstract](3) [PDF 0KB](0)
Abstract:
Amphiphilic macromolecular brushes with pH-responsiveness and reduction responsiveness were synthesized by reversible addition-fragmentation chain transfer polymerization and atom transfer radical polymerization. The side chains of the brush polymers were covalently connected to the backbones through redox-responsive disulfide bonds. The structure, molecular weight and molecular weight distribution of the brush polymers were characterized by 1H-NMR and gel permeation chromatography. At pH = 10.0, the amphiphilic brush polymers self-assembled into multi-component micelles with POEGMA shells and PtBMA/PDMAEMA cores. In the cores, the two hydrophobic blocks segregated into distinct domains due to their incompatibility, and the hydrophilic POEGMA blocks formed the coronae to stabilize the structures. The PtBMA chains with larger volume percentage formed the continuous phases, while the PDMAEMA chains with smaller volume percentage formed the discontinuous phases. At pH = 4.0, protonated PDMAEMA chains were highly stretched and formed the coronae of the micelles. Excessive reductant was added into the micellar solution to reduce the disulfide bonds between PDMAEMA side chains and the backbones, and mesoporous polymeric micelles with thiol groups inside the pores were obtained. 1H-NMR results of multi-component micelles, before and after treatment with the reductant, indicated that the PDMAEMA side chains were removed completely. Transmission electron microscopy (TEM) and dynamic light scattering were used to characterize the morphology and the size of the micelles. Based on TEM results, the average size of the pores in the micelles was about 2 nm, which was consistent with the average size of the PDMAEMA discontinuous phases. After the cleavage of the disulfide bonds and the removal of PDMAEMA chains from the micelles, thiol groups were produced on the walls of the pores. The thiol groups can be used as reducing agent and stabilizer in the in situ synthesis of gold nanoparticles. By thiol-bromine reactions, mesoporous micelles with polythiophene derivatives inside the pores were synthesized. The micelles showed high sensitivity and excellent selectivity for Hg2+.
Construction of Multifunctional Drug Nanocarriers by Modularized Host-Guest Self-assembly
Yin Wang, Hai-bo Wang, Hai-jie Han, Fan Jia, Qiao Jin, Jian Ji
2018, 0(8): 1089-1096.   doi: 10.11777/j.issn1000-3304.2018.18035
[Abstract](273) [FullText HTML](171) [PDF 1027KB](23)
Abstract:
Unlike the crude study conducted at the beginning of nanomedicine, researchers have devoted more efforts to developing nanosystems with elaborated structures and multifunctions owing to the fact that the tumor microenvironment is complicated. However, it is still a great challenge to prepare these nanoplatforms for drug delivery. In this study, multifunctional prodrug nanocarriers were fabricated by the modularized host-guest self-assembly between cholesterol and β-cyclodextrin. The targeted ligand lactobionic acid (LBA), fluorescent probe fluoresceine isothiocyanate (FITC), and chemtherapeutic drug doxorubicin (DOX) were integrated into the multifunctional supramolecualr drug nanocarriers. The host-guest interaction between Chol-PEG and β-CD-hydrazone-DOX was confirmed by 2D 1H NOESY spectrum. The modularized functional building blocks could self-assemble into micelles with a diameter of 20 nm. The supramolecular nanocarriers showed pH-sensitive drug release behavior. The release of DOX can be greatly accelerated in acidic endo/lysosomal pH. The internalization of the supramolecular drug nanocarriers by HepG2 cells was studied by fluorescence microscopy and flow cytometry. The nanocarriers can be well taken up by cancer cells. Due to the targeting ability of LBA, the internalization of the nanocarriers can be greatly inhibited if the cells are pre-treated by free LBA. At the same time, the fluorescence of FITC can be clearly observed intracellularly, which can be used to track the sub-cellular location of the drug nanocarriers. Finally, the cytotoxicity of the drug nanocarriers was investigaed by MTT assay. With the HepG2 cells pre-treated with free LBA, the cytotoxicity of the drug nanocarriers was significantly reduced, most probably owing to the unsatisfactory cell uptake. The concentration-dependent cytotoxicity toward HepG2 cells was also observed. Therefore, the integration of target ligand and imaging ligand have endowed the nanocarriers with targeted theranostic property. More importantly, since the modularized host-guest self-assembly is dynamically tunable, the percentage of functional ligands could be easily optimized to achieve a better outcome. Such multifunctional prodrug nanocarriers fabricated by modularized host-guest self-assembly may have great potential in drug delivery.
Stretchable and Functional Supramolecular Hydrogels Based on the Template Effect of Poly(β-cyclodextrin)
Li-yuan Wang, Ping-zhang Cheng, Ming-yu Guo
2018, 0(8): 1097-1106.   doi: 10.11777/j.issn1000-3304.2018.18041
[Abstract](412) [FullText HTML](322) [PDF 1177KB](51)
Abstract:
β-cyclodextrin-ferrocene host-guest inclusion complex has been widely used to construct various functional supramolecular hydrogels, but all these reported hydrogels are often very weak and/or brittle. In this work, β-cyclodextrin (β-CD) based linear copolymer (polyβ-CD) was synthesized and used as the macromolecular host, hydrophilic and flexible spacer modified ferrocene (Fc) monomer acted as the guest. The polymerizable Fc monomer was preloaded on polyβ-CD to form a novel type of ‘macromolecular supramolecular cross-linker’ (MSCL) owing to the inclusion complexation between β-CD and Fc. For the first time, stretchable, stab-resistant and adhesive supramolecular hydrogels were prepared via simple free-radical copolymerization of MSCL and acrylamide. Tensile-testing results showed that the obtained supramolecular hydrogel can be stretched up to more than 30 times of its original length without breaking. The gel can also be stabbed by sharp tips of scissors or pencil without fracture, indicating excellent stab resistance property. At the same time, the hydrogel also exhibited strong adhesion to the surfaces of human hand, hydrophilic glass or hydrophobic porcine skin. We attribute these distinguished behaviors to the successful use of polyβ-CD and the introduction of flexible hydrophilic spacer to the Fc monomer. Firstly, polyβ-CD acted as a macromolecular supramolecular imprint to form pre-organized Fc-polyβ-CD complexes, and thus resulted in relatively local high density of pendent Fc groups in the polymeric network. This is different from most of the reported host-guest interaction based supramolecular hydrogels, where the host and guest groups are randomly attached in the polymeric network. Secondly, after copolymerization, polyβ-CD was homogeneously immersed in the network by noncovalent interaction but not covalently conjugated in the network, which would greatly limit its mobility. Finally, the introduction of hydrophilic spacer on Fc not only can yield water soluble Fc-polyβ-CD macromolecular supramolecular complex, but also provide the released free Fc groups with more flexibility. Altogether, the local high density of both the guest and host groups in the network combined with their relatively high flexibility provided the present supramolecular hydrogels with excellent mechanical properties.
Disentanglement of Polylactide Melt by Oscillatory Shear Stress Field
Tian-yu Liu, Wei-jiao Jiang, Wei-xing Yang, Qin Zhang, Qiang Fu
2018, 0(8): 1107-1115.   doi: 10.11777/j.issn1000-3304.2018.18053
[Abstract](214) [FullText HTML](154) [PDF 754KB](15)
Abstract:
The Haake rotational rheometer was employed to disentangle the polylactide melt by well-controlled oscillatory shear stress with sinusoidal strain and to monitor the melt viscosity in real time. Fisrtly, a PLA sample was disentangled with different strains at various frequency ranges, and the results indicated that the PLA melt represented the lowest melt viscosity which was four orders of magnitude lower than that of the PLA without any treatment when the strain was 50% with the frequency at 3.5 Hz. Then, the molecular weights of all these PLA were measured by gel permeation chromatography (GPC) and almost no change was detected after the oscillatory shear. Taken into account the results of the melt viscosity and the molecular weight measurement, it was reasonable that the significant reduction of PLA melt viscosity was attributed to the effective disentanglement of PLA chains, rather than their degradation. Furthermore, the effect of oscillatory shear on glass transition, crystallization and melting behavior was also studied. It was found that the effective disentanglement of PLA chains was achieved by oscillatory shearing, leading to a lower glass transition temperature and a cold-crystallization temperature together with largely improved crystallinity of PLA. Simultaneously, when compared to the PLA melt without any treatment, the isothermal crystallization of PLA at 120 °C with the lowest melt viscosity also demonstrated that the oscillatory shear could disentangle the PLA melt and thus accelerated the crystallization of PLA. More importantly, the influence of annealing time (1 − 30 min) and temperature (180 − 200 °C) was investigated as well. The semi-crystallization time at 120 °C of disentangled PLA constantly increased with the increasing annealing time and temperature, which got gradually closer to that of PLA without any treatment. These results demonstrated that the disentanglement could be maintained at relatively low temperature and re-entangled rapidly at relatively high temperature. In summary, the Haake rotational rheometer, the common test instrument for the rheological properties of polymer melt, can be employed for the investigation of the disentanglement of polymer melt, which is not merely a simple and effective method to disentangle the polymer melt, but also a well-controlled and real-time monitoring approach for systematically investigating the disentanglement of polymer melt.
Monte Carlo Study on Self-assembly Behavior of Asymmetric Diblock Copolymers under Spherical Shell Confinement
Ying-ying Wang, Jia-ni Ma, Jie Cui, Yuan-yuan Han, Wei Jiang
2018, 0(8): 1116-1126.   doi: 10.11777/j.issn1000-3304.2018.18058
[Abstract](286) [FullText HTML](221) [PDF 1386KB](17)
Abstract:
Monte Carlo simulation was employed to investigate the self-assembly behaviors of asymmetric diblock copolymers under spherical shell confinements with different shell thicknesses and selectivity. The asymmetric diblock copolymer that can form hexagonally packed cylinders in bulk state was selected. The simulation results show that, when the cylinder-forming diblock copolymers are confined in spherical shells, the minority blocks can also form cylinder phases. It is found that the orientation of the cylinders highly depends on the shell thickness and selectivity. The formation of the cylinders, that are perpendicular to the shell surfaces and can penetrate the shell from inner to outer surfaces, is a prerequisite to obtain mesoporous polymer capsules. The formation conditions of such cylinders were elucidated in this study. In the neutral spherical shell, the simulation results indicate that the formation of the cylinders that penetrate the shell depends on the structural frustration parameter (i.e., the ratio of the shell thickness D to the equilibrium spacing between the cylinders in bulk, L0). When D is incomparable to L0, the cylinders that penetrate the shell are oberved, otherwise, the cylinders that penetrate the shell disappear. It is interesting to find that the weak repulsions between the shell boundaries and the minority blocks are favorable for the minority blocks to form branched cylinders. The branched cylinders penetrate the shell from inner to outer surfaces and form multiple channels in the shell, which benefits to fabricate polymer capsules with multiple release channels. And the formation of such branched cylinders does not depend on the structural frustration parameter D/L0. On the other hand, in the case of spherical shell with a thin thickness, the minority blocks always form well-defined cylinders that penetrate the shell, no matter whether the repulsions between the shell boundaries and the minority blocks exist. Via investigating the orientation of the polymer chains in each shell, the influence of the shell thicknesses and the repulsions between the shell boundaries and the minority blocks on the orientation of cylinders formed by the minority blocks is further elucidated.
Trypsin-responsive Near-infrared Fluorescent/Magnetic Resonance Dual-imaging Composite Nanospheres Based on Self-assembly
He-ze Guo, Sheng Song, Ting-ting Dai, Sheng-li Li, Hong-jing Dou
2018, 0(8): 1127-1140.   doi: 10.11777/j.issn1000-3304.2018.18079
[Abstract](104) [FullText HTML](81) [PDF 1448KB](3)
Abstract:
The trypsin-responsive near-infrared fluorescent/magnetic resonance dual-imaging composite nanospheres, which consist of PAA-decorated Fe3O4 magnetic nanoparticles (MNPs) that serve as the magnetic resonance imaging (MRI) agents and Cy5.5-modified poly-L-lysine (Cy5.5-PLL) as the trypsin-responsive substrate and fluorescent carrier, were successfully fabricated via self-assembly method. The MNPs present negatively charge due to the carboxyl groups from PAA on their surface and the Cy5.5-PLL present positively charge due to the amino groups in PLL chains. The construction of the composite nanospheres was initially performed via the self-assembly driven by the electrostatic interactions between the above mentioned oppositely charged precursors. Subsequently, glutaraldehyde (GA) was introduced to partially crosslink the amino groups in PLL and stabilize the nanospheres. The fluorescent and magnetic characterization of the two precursors of the composite nanospheres, Cy5.5-PLL and MNPs, indicated that Cy5.5-PLL chains showed obvious fluorescent signal and the MNPs displayed the superparamagnetism property. However, the notable fluorescent signal from Cy5.5-PLL in native soluble state was self-quenched thanks to the short distance among the Cy5.5 fluorescent molecules after the construction of the nanospheres. Additionally, the structure of the as-prepared self-assembled nanospheres was stable, resulting from the almost unchanged results of the hydrodynamic size and fluorescence intensity of nanospheres in different buffer solutions. Nevertheless, because of the sensitivity of PLL chains to trypsin, the nanospheres were selectively disintegrated into fragmented segments under the hydrolysis by trypsin, leading to 18-fold amplification of fluorescent intensity in comparison with the self-assembled nanospheres in quenched state. Moreover, the magnetic resonance imaging enhancement was also related to the disintegration of the nanospheres. As expected, the trypsin-positive cells incubated with nanospheres exhibited remarkable fluorescent imaging due to the disintegration of the nanospheres into debris, whereas this disintegration did not take place for the trypsin-negative cells. In vivo fluorescent images of the composite nanospheres in normal nude mice further verified the trypsin-triggered fluorescent imaging. Cytotoxicity study demonstrated that the composite nanospheres presented low toxicity to several cell lines, and exhibited remarkable near-infrared fluorescent/magnetic resonance imaging capabilities, which were sensitive to the presence of trypsin and thus provided excellent opportunity to serve as dual-imaging agents.
PROGRESS IN THE DEVELOPMENT OF BIOMEDICAL POLYMER MATERIALS FABRICATED BY 3-DIMENSIONAL PRINTING TECHNOLOGY
Chao-liang He, Zhao-hui Tang, Hua-yu Tian, Xue-si Chen
2013, (6): 722-732.   doi: 10.3724/SP.J.1105.2013.12430
[Abstract](1981) [PDF 2304KB](470)
PREPARATION OF MELAMINE MOLECULARLY IMPRINTED POLYMER MICROSPHERES BY PRECIPITATION POLYMERIZATION
YANG Weihai, YAN Shoulei, WEI Chen, WANG Qingzhang
2010, (10): 1163-1169.   doi: 10.3724/SP.J.1105.2010.09347
[Abstract](2404) [PDF 933KB](1020)
NATURAL POLYMER MATERIALRECENT STUDIES ON EUCOMMIA ULMOIDES GUM
ZHANG Ji-Chuan, XUE Zhao-Hong, YAN Rui-Fang, FANG Shi-Bi
2011, (10): 1105-1117.   doi: 10.3724/SP.J.1105.2011.11076
[Abstract](2791) [PDF 1224KB](1031)
Organic Solar Cells with an Efficiency Approaching 15%
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