仿细胞膜结构共聚物的合成及涂层性能

采用饥饿法将2-甲基丙烯酰氧乙基磷酰胆碱(MPC)分别与甲基丙烯酸十八烷基酯(SMA)、 甲基丙烯酸十二烷基酯(LMA)及甲基丙烯酸正丁酯(BMA)聚合, 通过改变投料比例和沉淀剂种类, 合成了一系列含磷酰胆碱基团的仿细胞膜结构的两亲性二元随机共聚物. ¹H NMR和元素分析结果表明, 合成的两亲性二元随机共聚物的组成与投料比相近. DSC结果表明, 聚合物具有较低的玻璃化转变温度. 表面张力及水的动态接触角(DCA)研究发现, 聚合物涂层表面具有明显的两亲性及表面结构易变性, 在空气中憎水基团在表面取向, 在水环境中亲水的磷酰胆碱基团则迁移取向到涂层表面形成仿细胞外层膜结构界面, 最终形成不溶于水的仿细胞膜结构涂层.     

含氟两亲接枝共聚物的制备及其与牛血清蛋白作用的研究

用端基反应法合成了对乙烯基苄基的聚乙二醇大分子单体,将该大分子单体与甲基丙烯酸六氟丁酯共聚,合成了一种含氟两亲接枝共聚物.利用1H-NMR1、9F-NMR、GPC对大分子单体和两亲接枝共聚物进行了表征.表面张力法测定了两亲接枝共聚物的临界胶束浓度,发现随着共聚物中含氟链段含量的增加,其临界胶束浓度降低.采用荧光光谱研究了含氟两亲接枝共聚物与牛血清蛋白(BSA)的相互作用,结果表明由于含氟链段疏水力的作用,含氟两亲接枝共聚物能与牛血清蛋白发生相互作用使其荧光增强,随着含氟两亲接枝共聚物浓度和共聚物中含氟链段含量的增加,荧光增强幅度加大.通过透射电子显微镜(TEM)和激光光散射粒度仪(PCS)测试发现,当BSA加入到含氟两亲接枝共聚物的胶束溶液后,所得胶束的粒径和粒径分布变大,共聚物胶束由规整的实心核壳结构变为囊泡状核壳结构.     

Synthesis of Amphiphilic Graft Copolymers with Poly(2‐methyl‐2‐oxazoline) Side Chains and a Backbone Containing Chloromethylstyrene and Methyl Methacrylate

New amphiphilic graft copolymers were synthesized by means of a cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline initiated with a statistical copolymer of methyl methacrylate and chloromethylstyrene. The synthesis was carried out in benzonitrile at 110°C. The grafting reaction was quantitative and the yield of grafting was more than 90%percent;. The graft copolymers were characterized by means of NMR, FT‐IR, and UV‐VIS spectroscopy, as well as elemental analysis and viscosity measurements of their aqueous solutions. The graft copolymers revealed amphiphilic properties and evidence for the formation of micelles and molecular aggregates in aqueous solution. Graft copolymers with relatively short lateral chains are soluble in methanol but insoluble in water, while the copolymers with longer lateral chains are soluble in both methanol and water.     

Amphiphilic comb-shaped polymers from poly(ethylene glycol) macromonomers

Comb-shaped amphiphilic graft copolymers composed of hydrophobic backbones and hydrophilic side chains were prepared by radical copolymerization of poly(ethylene glycol) monomethacrylate macromonomers, and methacrylate and acrylate comonomers in toluene. The copolymerizations were very sensitive to the reaction conditions, and insoluble cross-linked gels were easily formed. The yields of soluble copolymers were affected by the initiator concentration, the macromonomer concentration, and the choice of chain transfer agents and comonomers. Solubilities of the copolymers in water or methanol were found to depend on the sizes and the numbers of the PEG side chains. The copolymers showed surface activity with CMC:s in the order of 0.1–1.5 g/L and surface tensions of 36–56 dyn/cm. When tested as emulsifiers most of the copolymers gave oil-in-water type emulsions at room temperature. Polymers carrying MPEG 2000 side chains were crystalline with melting points of 38–44°C, while those based on PEG 400 and 1000 were mostly amorphous with glass transition temperatures between -55 and -60°C. © 1992 John Wiley & Sons, Inc.     

ABA and Star Amphiphilic Block Copolymers Composed of Polymethacrylate Bearing a Galactose Fragment and Poly(ε‐caprolactone)

Novel ABA and star amphiphilic block copolymers of poly(vinyl sugars) with biodegradable hydrophobic poly(ε‐caprolactone) segments are presented. They were prepared by a combination of ring‐opening polymerization of ε‐caprolactone and atom‐transfer radical polymerization of methacrylate‐bearing isopropylidene‐protected galactose. Subsequently, the protecting groups of the sugar fragments were removed by treatment with 80% formic acid.     

Unprecedented diverse nanostructures formed by amphiphilic graft copolymer bearing PEO side chains synthesized by ATNRC

A series of well‐defined amphiphilic graft copolymers bearing hydrophilic poly(ethylene oxide) (PEO) side chains with tunable grafting densities were synthesized by atom transfer nitroxide radical coupling (ATNRC) reaction using CuBr/PMDETA as catalytic system via the grafting‐onto strategy. PEO side chains were linked to α‐C of carbonyl of polyacrylate‐based backbone, not to the ester side groups as usual, so that every repeating unit of the backbone possessed a pendant steric bulky tert‐butyl group. The critical micelle concentrations of the obtained amphiphilic graft copolymers in aqueous media determined by fluorescence probe technique using pyrene as probe increased with the raising of molecular weights. These amphiphilic graft copolymers with novel chemical structure showed unprecedented diverse nanostructures visualized by transmission electron microscopy in aqueous media and micellar morphologies varied with the changing of experiment parameters. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis and reversible hydration–dehydration system of copolymers bearing a vicinal tricarbonyl structure

Novel copolymers composed of a styrene (St) derivative bearing a vicinal tricarbonyl moiety and various vinyl monomers such as St, methyl methacrylate (MMA), and N‐vinylpyrrolidone (NVP) were synthesized by (1) radical copolymerization of a St derivative with a 1,3‐diketone structure with St, MMA, and NVP and (2) successive oxidation of the resulting copolymers with N‐bromosuccinimide in DMSO to convert their 1,3‐diketone moieties in the side chains into the corresponding vicinal tricarbonyl moieties. Their tricarbonyl moieties were readily hydrated in water‐containing acetone to generate the corresponding copolymers bearing geminal diol structures in the side chains. On the other hand, heating the resulting copolymers bearing the geminal diol structures in vacuo‐enabled successful recovery of the vicinal tricarbonyl moieties to demonstrate the reversible nature of this system. The hydration behavior in powdery state under air atmosphere saturated by water was also investigated. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

End group polarity and block symmetry effects on cloud point and hydrodynamic diameter of thermoresponsive block copolymers

Thermoresponsive block copolymers are of interest for delivery vehicles in the body. Often an interior domain is designed for the active agent and the exterior domain provides stability in the bloodstream, and may carry a targeting ligand. There is still much to learn about how block sequence and chain end identity affect micelle structure, size, and cloud points. Here, hydrophilic oligo(ethylene glycol) methyl ether acrylate and more hydrophobic di(ethylene glycol) methyl ether methacrylate monomers were polymerized to give amphiphilic block copolymers with amphiphilic chain ends. The block sequence and chain end identity were both controlled by appropriate choice of RAFT chain transfer agents to study the effect of ‘matched’ and ‘mismatched’ chain end polarity with amphiphilic block sequence. The affect of matching or mismatching chain end polarity and block sequence was studied on the hydrodynamic diameter, cloud point, and temperature range of the chain collapse on linear di‐ and triblock copolymers and star diblock polymers. The affects of matching or mismatching chain end polarity were significant with linear diblock copolymers but more complex with triblock and star copolymers. Explanations of these results may help guide others in designing thermoresponsive block copolymers. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2838–2848     

Synthesis and characterization of polycholesteryl methacrylate–polyhydroxyethyl methyacrylate block copolymers

We report the synthesis and characterization of a series of novel diblock copolymers, poly(cholesteryl methacrylate‐b‐2‐hydroxyethyl methacrylate) (PCMA‐b‐PHEMA). Monomers, cholesteryl methacrylate (CMA) and 2‐(trimethylsiloxy)ethyl methacrylate (HEMA‐TMS), were prepared from methyacryloyl chloride and 2‐hydroxyethyl methacrylate, respectively. Homopolymers of CMA, PCMA, with well‐defined molecular weights and polydispersity indices (PDI), were prepared by reversible addition fragmentation and chain transfer (RAFT) method. Precursor diblock copolymers, PCMA‐b‐P(HEMA‐TMS), were synthesized using PCMA as macromolecular chain transfer agent and monomer, HEMA‐TMS. Product diblock copolymers, PCMA‐b‐PHEMA, were prepared by deprotecting trimethylsilyl units in the precursor diblock copolymers using acid catalysts. Detailed molecular characterization of the precursor diblock copolymers, PCMA‐b‐P(HEMA‐TMS), and the product diblock copolymers, PCMA‐b‐PHEMA, confirmed the composition and structure of these polymers. This versatile synthetic strategy can be used to prepare new amphiphilic block copolymers with cholesterol in one block and hydrogen‐bonding moieties in the second block. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6801–6809, 2008     

Poly(butyl methacrylate-g-methoxypoly(ethylene glycol)) and poly(methyl methacrylate-g-methoxypoly(ethylene glycol)) graft copolymers: preparation and aqueous solution properties

A series of water-soluble, amphiphilic graft copolymers has been prepared by free-radical copolymerization of methoxypoly(ethylene glycol) macromonomers, with either methyl methacrylate or butyl methacrylate as the comonomers, in water/ethanol solvent mixtures. Lower molecular weight copolymers were obtained by increasing the concentration of the initiator, azobisisobutyronitrile (AIBN), used in the polymerization reaction. However, the route used also led to the formation of significant quantities of tetramethylsuccinodinitrile, a toxic byproduct resulting from the cage reaction of AIBN. Static fluorescence measurements using pyrene as a probe, along with 1H NMR experiments, showed that the graft copolymers form aggregates in water at very low concentrations (approximately 0.01 g l(-1)) with the pendant hydrophilic graft chains forming a stabilizing shell around the hydrophobic backbone. An increase in the hydrophile-lipophile balance of the graft copolymers was found to lead to smaller aggregates with lower aggregation numbers and highly swollen hydrophilic shells, as revealed by small angle neutron scattering (SANS).     

Graft polymerization of 2-hydroxyethyl methacrylate via ATRP with poly(acrylonitrile-co-p-chloromethyl styrene) as a macroinitiator

Amphiphilic graft copolymers are excellent additives for the development of antifouling membranes by nonsolvent induced phase separation. We report a convenient approach to the synthesis of novel graft copolymers with hydrophobic polyacrylonitrile (PAN) backbones and hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) side chains. Atom transfer radical polymerization (ATRP) of 2-hydroxyethyl methacrylate was carried out with poly(acrylonitrile-co-p-chloromethyl styrene) (PAN-co-PCMS) as a macroinitiator in the presence of CuCl/2,2’-bipyridine at 50 °C in dimethyl sulfoxide. Kinetics of the graft polymerization was also evaluated. The synthesis of poly(acrylonitrile-co-p-chloromethyl styrene-g-2-hydroxyethyl methacrylate) (PAN-co-(PCMS-g-PHEMA)) can be relatively controlled when CMS (the ATRP sites) unit in the macroinitiator is around 5 mol%. Both the macroinitiators and graft copolymers were characterized by FTIR, NMR and GPC. The surface morphology and wettability of the copolymer films were studied by AFM and water contact angle measurement, respectively. We demonstrate that phase segregation between the PAN-co-PCMS backbones and the PHEMA side chains takes place and the surface hydrophilicity of the graft copolymers increases with the length of the PHEMA side chains. Because these amphiphilic graft copolymers can be synthesized in mass, they will be useful as latent additives for the fabrication of advanced PAN separation membranes.     

窄分布聚丙烯酸-g-聚甲基丙烯酸酯接枝共聚物的合成

利用合成的一种新型原子转移自由基聚合大分子引发剂和从主干接枝的方法制备了窄分布的两亲性接枝共聚物聚丙烯酸-g-聚甲基丙烯酸酯, 并对其结构进行表征. 产物主链和侧链的分子量可分别通过调整单体与引发剂的投料比和反应时间进行控制, 结构规整, 侧链单体适用范围广. 该合成方法不仅推动了接枝共聚物合成研究的进展, 其产物更为两亲性接枝共聚物自组装行为的研究提供了很好的研究对象.     

含氟两亲接枝共聚物的制备及其结晶行为

采用大分子单体技术合成了一系列以聚乙二醇为支链、甲基丙烯酸六氟丁酯为主链的含氟两亲接枝共聚物(PHFMA-g-PSPEG)。用1HNMR和凝胶色谱(GPC)对制备的大分子单体和两亲接枝共聚物的结构进行了表征。利用示差扫描量热法(DSC)、X射线衍射(XRD)和偏光显微镜(POM)测试技术对含氟两亲接枝共聚物的结晶行为进行了研究。DSC和XRD结果表明,随着共聚物中含氟链段质量分数的增加,其结晶温度(Tc)和结晶度(Xc)均降低,而结晶熔融温度(Tm)先减小后增加。POM发现,随着共聚物中含氟链段质量分数的增加,其结晶速度减慢,共聚物形成清晰球晶的能力减弱,当共聚物中含氟链段质量分数为57%时,含氟两亲接枝共聚物已不能形成清晰的球晶。     

The Role of Hydrophobicity in the Antimicrobial and Hemolytic Activities of Polymethacrylate Derivatives

We synthesized cationic random amphiphilic copolymers by radical copolymerization of methacrylate monomers with cationic or hydrophobic groups and evaluated their antimicrobial and hemolytic activities. The nature of the hydrophobic groups, and polymer composition and length were systematically varied to investigate how structural parameters affect polymer activity. This allowed us to obtain the optimal composition of polymers suitable to act as non-toxic antimicrobials as well as non-selective polymeric biocides. The antimicrobial activity depends sigmoidally on the mole fraction of hydrophobic groups (f_HB). The hemolytic activity increases as f_HB increases and levels off at high values of f_HB, especially for the high-molecular-weight polymers. Plots of HC₅₀ values versus the number of hydrophobic side chains in a polymer chain for each polymer series showed a good correlation and linear relationship in the log–log plots. We also developed a theoretical model to analyze the hemolytic activity of polymers and demonstrated that the hemolytic activity can be described as a balance of membrane binding of polymers through partitioning of hydrophobic side chains into lipid layers and the hydrophobic collapsing of polymer chains. The study on the membrane binding of dye-labeled polymers to large, unilamellar vesicles showed that the hydrophobicity of polymers enhances their binding to lipid bilayers and induces collapse of the polymer chain in solution, reducing the apparent affinity of polymers for the membranes.     

Synthesis of new amphiphilic block copolymers. Block copolymer of sulfonated glycidyl methacrylate and alkyl methacrylate

Water-soluble amphiphilic block copolymers consisting of a hydrophobic block of poly(alkyl methacrylate) and a hydrophilic anionic polyelectrolyte block have been synthesized by a living anionic polymerization of methyl methacrylate and glycidyl methacrylate and subsequent selective modification of the oxirane groups of the glycidyl methacrylate block into hydroxysulfonate groups by a phase transfer catalyzed sulfonation reaction. The block copolymers were characterized by a predictable motecular weight and a narrow molecular weight distribution while the yield was quantitative. These amphiphilic block copolymers display surfaceactive behavior in water and they are characterized by a critical micelle concentration.     

Preparation and self-assembly of pH-sensitive amphiphilic comb-shaped copolymer containing long fluorinated side chains

Novel pH-sensitive amphiphilic comb-shaped copolymers containing long fluorinated side chains, which combined the characteristics of pH-sensitivity from pendent tertiary amine groups, unique hydrophobic and fluorophobic characteristic from the fluorinated moieties and hydrophilicity from the poly (ethylene glycol) segments, were designed and synthesized via radical polymerizaion of 2-(Dimethylamino) ethyl methacrylate (DMAEMA), poly (ethylene glycol) methyl ether methacrylate (PEGMA) and homemade fluorinated macromonomer (PHFBMA-GMA). The physicochemical properties of polymeric micelles prepared therefrom were investigated. The chemical structures of the copolymers were characterized by GPC, FTIR and ¹H-NMR. The critical micelle concentrations (CMC) of the copolymers in different pH (5.0 and 7.4) were determined by fluorescence spectroscopy. Larger CMCs could be obtained in lower pH since the pronation of DMAEMA moieties enhanced the hydrophilicity. With increasing the amount, as well as the molecular weight, of PHFBMA-GMA, CMC decreased significantly. As pH decreased, particle size, as well as zeta potential of the polymeric micelles increased significantly, indicating significant pH-sensitivity of the polymeric micelles. Furthermore, larger polymeric micelles were obtained with larger amount, as well as higher molecular weight, of PHFBMA-GMA. Transmission electron microscopy (TEM) showed that the morphological shapes of the copolymers performed spherical micelles. The cytotoxicity test showed that the comb-shaped copolymers performed extremely low cytotoxicity. The pH-sensitive polymeric micelles prepared from the amphiphilic comb-shaped copolymers containing long fluorinated side chains could be potential candidates for nanotanks for hydrophobic or fluorophobic molecules and drug carriers and the facile preparation might fit for large scale industrialization.     

Interfacial crosslinking of self‐assembled triblock copolymer nanoparticles via alkoxysilane hydrolysis and condensation

The use of amphiphilic triblock copolymers bearing a reactive alkoxysilane middle block as polymeric stabilizers is reported in this work. A series of poly(ethylene glycol) methyl ether methacrylate‐b‐(3‐trimethoxysilyl)propyl methacrylate‐b‐benzyl methacrylate (PEGMA‐b‐MPS‐b‐BzMA) triblock copolymers were prepared by RAFT solution polymerization and polymerization‐induced self‐assembly (PISA), respectively, where the various block lengths and overall composition were varied. The copolymers prepared by solution polymerization were employed as oil‐in‐water stabilizers where upon application of a catalyst, the 3‐(trimethoxysilyl)propyl methacrylate (MPS) block at the droplet interface was crosslinked to yield capsule‐like structures. The effectiveness of interfacial crosslinking was validated by dynamic light scattering and electron microscopy. In situ self‐assembly by the PISA method resulted in spherical nanoparticles of controllable size that were readily crosslinked by addition of base, with significant enhancement of colloidal stability. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1897–1907     

N-异丙基丙烯酰胺类共聚物温敏性研究

制备了N-异丙基丙烯酰胺(NIPAAm)与N,N-二甲基丙烯酰胺(DMAAm)和/或甲基丙烯酸羟乙酯(HEMA)的二元及三元共聚物,研究了组成和链转移剂用量对共聚物温敏性的影响,并在上述三元共聚物上接枝聚己内酯(PCL)得到温敏性两亲聚合物.结果表明,随着DMAAm增加、HEMA减少或共聚物分子量降低,共聚物的最低临界溶解温度升高,且PCL链段的接枝度和长度对聚合物的温敏性影响明显.     

Contact Active Antimicrobial Coatings Prepared by Polymer Blending

Herein, contact active antimicrobial films are prepared by simply blending cationic amphiphilic block copolymers with commercial polystyrene (PS). The copolymers are prepared by combining atom transfer radical polymerization and “click chemistry.” A variety of copolymers are synthesized, and composed of a PS segment and an antimicrobial block bearing flexible side chain with thiazole and triazole groups, 4‐(1‐(2‐(4‐methylthiazol‐5‐yl)ethyl)‐1H‐1,2,3‐triazol‐4‐yl) butyl methacrylate (TTBM). The length of the TTBM block is varied as well as the alkylating agent. Different films are prepared from N,N‐dimethylformamide solution, containing variable PS‐b‐PTTBM/PS ratio: from 0 to 100 wt%. Remarkably, the blend films, especially those with 30 and 50 wt% of copolymers, exhibit excellent antimicrobial activities against Gram‐positive, Gram‐negative bacteria and fungi, even higher than films prepared exclusively from the cationic copolymers. Blends composed of 50 wt% of the copolymers present a more than 99.999% killing efficiency against the studied microorganisms. The better activity found in blends can be due to the higher roughness, which increases the surface area and consequently the contact with the microorganisms. These results demonstrate that the use of blends implies a reduction of the content of antimicrobial agent and also enhances the antimicrobial activity, providing new insights for the better designing of antimicrobial coatings.     

Biologically active polymers. V. Synthesis and antimicrobial activity of modified poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) derivatives with quaternary ammonium and phosphonium salts

Antimicrobial copolymers bearing quaternary ammonium and phosphonium salts based on a copolymer of glycidyl methacrylate and 2‐hydroxyethyl methacrylate were synthesized. Poly(glycidyl methacrylate‐co‐2‐hydroxyethyl methacrylate) was modified for the introduction of chloromethyl groups by its reaction with chloroacetyl chloride. The chloroacetylated copolymer was modified for the production of quaternary ammonium or phosphonium salts. The antimicrobial activity of the obtained copolymers was studied against gram‐negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Shigella sp., and Salmonella typhae), gram‐positive bacteria (Bacillus subtilus and B. cereus), and the fungus Trichophyton rubrum by the cut‐plug method. The results showed that the three copolymers had high antimicrobial activity. A control experiment was carried out on the main polymer without ammonium or phosphonium groups. The copolymer bearing quaternary salt made from tributyl phosphine was the most effective copolymer against both gram‐negative and gram‐positive bacteria and the fungus T. rubrum. The diameters of the inhibition zones ranged between 20 and 60 mm after 24 h. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2384–2393, 2002