pH和CO_2响应性嵌段共聚物的合成及其自组装行为

采用可逆加成-断裂链转移自由基聚合(RAFT)和开环聚合(ROP)合成一种具有双重敏感性的聚甲基丙烯酸N,N-二甲氨基乙酯-b-聚乳酸(PDMAEMA-b-PLA)嵌段共聚物。利用傅里叶变换红外光谱(FTIR)、核磁共振波谱(1HNMR)对双亲性嵌段共聚物的结构进行表征;用紫外-可见分光光度计(UV-Vis)、Zeta电位及粒度分析仪和扫描电子显微镜(SEM)研究了其自组装行为及聚集体的大小、形态变化,结果表明,嵌段共聚物在酸性和中性条件下有pH敏感性和CO2响应性,且具有良好的可逆性。     

聚（3-己基噻吩）-聚苯乙烯嵌段共聚物的一锅法制备

采用具有聚苯乙烯高分子链为配位基团的聚合催化剂，催化2,5-二溴-3-己基噻吩单体进行Kumada缩聚反应，利用一锅法制备了聚（3-己基噻吩）-聚苯乙烯嵌段共聚物。结果表明：采用一锅法，在室温、常压条件下进行一步聚合直接生成嵌段共聚物，反应过程简单，聚（3-己基噻吩）与聚苯乙烯嵌段对接率接近100%；与聚（3-己基噻吩）相比，聚（3-己基噻吩）-聚苯乙烯嵌段共聚物的结晶性能更好。     

DPE法合成双亲性丙烯酸酯嵌段共聚物及用于颜料分散剂的研究

以1,1-二苯基乙烯（DPE）为分子量调节剂,偶氮二异丁腈（AIBN）为引发剂进行甲基丙烯酸丁酯（BMA）的可控自由基聚合（DPE法）。研究了溶剂、DPE用量及反应温度对于聚合的影响,得到分子量分布较窄（PDI=1.43）的含有DPE半醌式休眠种结构的聚甲基丙烯酸丁酯（PBMA）。以PBMA为引发剂引发甲基丙烯酸二甲氨基乙酯（DMAEMA）聚合,得到分子量分布较窄的（PDI=2.0）双亲性嵌段共聚物（PBMA-b-PDMAEMA）。核磁共振氢谱（¹H NMR）测得共聚物组成与GPC测试结果相近。差示扫描量热分析（DSC）测试表明嵌段共聚物在11℃和35℃处有两个玻璃化转变温度。色浆的流变和粒径测试及漆膜性能测试表明,将所得双亲性嵌段共聚物作为酞菁蓝颜料分散剂,可以明显提高酞菁蓝颜料在丙烯酸酯树脂中的分散效率。     

含聚乙二醇的嵌段共聚物的合成及自组装研究进展

综述了通过活性自由基聚合如原子转移自由基聚合（ATRP）、氮氧稳定自由基聚合（NMP）、可逆加成断裂链转移聚合（RAFT）等方法合成含聚乙二醇（PEG）的嵌段共聚物的研究进展,并对含PEG类嵌段共聚物在溶液中的自组装技术和在药物载体、介孔材料以及碳纳米管中的应用进行了归纳,指出含PEG的嵌段共聚物可以自组装成多种形貌,直接影响材料的性能和应用,所以这些结构有潜在的应用价值和应用前景,并且合成新的含PEG的嵌段共聚物和开发具有新型结构、形貌可控的自组装体以及新的应用领域是今后的一个热点问题,具有重要的科学研究意义和实际应用价值。     

基于偏氯乙烯嵌段共聚物的多级多孔炭的制备

采用可逆加成-断裂链转移（RAFT）活性自由基聚合制备了聚苯乙烯-b-聚偏氯乙烯-b-聚苯乙烯嵌段共聚物（PS-b-PVDC-b-PS）,以此嵌段共聚物为碳前驱体,直接碳化制备微孔-中孔复合多级多孔炭。采用凝胶渗透色谱仪和核磁共振仪表征了嵌段共聚物结构,表明通过RAFT聚合可制得分子量较高（M_n^GPC >6000 g·mol^-1）和分子量分布较窄（PDI<1.5）的PS-b-PVDC-b-PS。采用热重分析表征嵌段共聚物热解特性,采用扫描电镜、N₂吸脱附表征多孔炭形貌和孔隙结构。结果表明嵌段共聚物同时具有PVDC和PS链段的热失重峰,PS链段可完全热解而具有形成中孔的模板作用,PVDC链段热降解形成含微孔的炭骨架,最终形成兼有微孔和中孔的多级多孔炭;随着PS嵌段含量的增加,嵌段共聚物的成炭率逐渐降低,孔隙尺寸逐渐增大;当PS/PVDC聚合度比为4.3时,多孔炭的比表面积、中孔率和平均孔径达到最大,分别为839 m²·g^-1、54%和2.02 nm。     

ARGET-ATRP合成双亲性嵌段共聚物及对二氧化钛分散效率的影响

以CuBr2（相对于单体物质的量的0.02%或0.01%）和还原剂、配体混合物为催化体系进行甲基丙烯酸 2(N,N-二甲氨基)乙酯（DMAEMA）的电子转移再生催化剂原子转移自由基聚合（ARGET-ATRP）,研究了溶剂、配体和还原剂种类对聚合的影响,得到分子量分布较窄的（PDI=1.56）聚甲基丙烯酸 2(N,N-二甲氨基)乙酯（PDMAEMA-Br）。以PDMAEMA-Br为引发剂引发丙烯酸丁酯进行“一步法”ARGET-ATRP聚合,得到分子量分布很窄的（PDI=1.4）双亲性嵌段共聚物（PDMAEMA-bPBA)。核磁共振氢谱（1H NMR）测得共聚物组成与GPC测试结果相近。差示扫描量热分析（DSC）测试表明嵌段共聚物在-40.1℃和123.5℃处有两个玻璃化转变温度。该方法大大降低了铜盐催化剂的用量,降低了制备成本,使聚合产物的后处理更容易进行。所得双亲性嵌段共聚物可以作为分散剂,明显提高了二氧化钛在环氧树脂中的分散效率。     

两亲性嵌段共聚物的合成及其自组装行为

采用原子转移自由基聚合（ATRP）方法合成了两亲性嵌段共聚物PSt-b-PAA。用1H NMR和GPC等手段对活性聚合进行了确认,对嵌段共聚物的结构进行了表征。两亲性嵌段共聚物在离子液体1-丁基-3-甲基咪唑六氟磷酸盐（[BM IM][PF6]）中形成胶束溶液。用透射电子显微镜（TEM）观察聚合物在离子液体中形成胶束的纳米结构。当疏水链长固定时,胶束的自组装形状主要依赖于亲水链的长度。两亲性共聚物在离子液体中可自组装成可控制结构的纳米胶束,这种纳米胶束可应用在很多领域。     

pH及温度双重敏感水凝胶的制备与性能研究

采用开环聚合的方法制备了Pluronic/寡聚ε-己内酯嵌段共聚物,该共聚物通过酰氯化反应得到了端基结构为丙烯双键的大分子单体;最后以氧化还原引发剂、采用自由基共聚合方法制备了聚（甲基丙烯酸-co-酰氯化大单体）共聚型水凝胶。性能分析表明所制备水凝胶具有良好的pH和温度双重敏感性。     

以聚（异戊二烯-苯乙烯）嵌段共聚物为“接枝剂”活性碳正离子聚合制备星形支化丁基橡胶

通过活性负离子聚合制备的聚（异戊二烯-苯乙烯）嵌段共聚物作为“接枝剂”,在2-氯-2,4,4-三甲基戊烷/TiCl4/质子捕捉剂的引发剂体系中,通过活性碳正离子聚合制备了星形支化丁基橡胶。结果表明,聚（异戊二烯-苯乙烯）嵌段共聚物的接枝效果明显,所得聚合物的空间排斥色谱图呈现明显的双峰,相对分子质量分布加宽;     

RAFT聚合制备嵌段共聚物的研究进展

RAFT聚合具有反应条件温和,对单体纯度和环境的要求相对较低等优势,近年来通过RAFT方法制备嵌段共聚物已经受到了高分子化学领域研究者的广泛关注。简要介绍了近10年来通过RAFT方法制备嵌段共聚物所常用的RAFT试剂和单体的研究进展,主要介绍了近10年来线型两嵌段、三嵌段共聚物和星型嵌段共聚物的RAFT聚合及应用。     

Triblock copolymers of 2-methyl-2-oxazoline and poly(ethyleneglycoladipate)

Summary 2-methyl-2-oxazoline was polymerized by using poly(ethyleneglycoladipate) having tosylate end groups as an initiator. Polymerization was carried in bulk, and ABA type block copolymers were obtained containing poly(N-acetylethylenimine) as A block (hard part) and poly(ethyleneglycoladlpate) as B block (soft part).     

Protein encapsulation in biodegradable amphiphilic microspheres. I. Polymer synthesis and characterization and microsphere elaboration

Polymerization of lactide on monomethoxypolyoxyethylene (MPOE), using stannous octoate as a catalyst, was carried out in bulk and in solvent. Polymerization in a solvent permits one to work at a lower temperature and thus to prevent transesterification reactions. The copolymers synthesized in solvent exhibited a lower polydispersity and a polylactic acid (PLA) block longer and closer to the expected one. Therefore, this procedure was used to synthesize a series of diblock copolymers MPOE–D ,L -PLA, keeping the PLA chain constant (45,000 g/mol), the MPOE block increasing from 2000 to 5000, 10,000, 15,000, and 20,000 g/mol. The longer the MPOE chain, the higher the water uptake in the MPOE–PLA films and the lower the glass transition temperature of the copolymers. The synthesized copolymers were used to prepare microspheres by the double-emulsion method. The PLA microspheres possess a smooth surface, whereas those made from copolymers have a rough surface with irregularity increasing with the molecular weight of MPOE. The size of these microspheres depends on the amphiphilic nature of the copolymers, their hydrophilicity, and their intrinsic viscosity in the organic solvent. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1695–1702, 1998     

Synthesis of PPP-b-PS block copolymers using a combination of Suzuki-polycondensation and nitroxide-mediated radical polymerization

The synthesis of π-conjugated Nitroxide-Mediated Radical Polymerization (NMRP)-macroinitiators by Suzuki-polycondensation in a one-step reaction has been investigated using conventional and microwave-heating in presence of a suitable terminating agent. Alkoxyamine-functionalized poly(para-phenylene)s were initially synthesized by Suzuki-polycondensation and then its block copolymer with styrene by NMRP. Molecular weight and molecular weight distribution of the polymers have been determined in SEC-measurements, while end-group determination was performed with MALDI-ToF-MS. Thin-layer-morphologies of the block copolymers were investigated using tapping-mode AFM.     

Preparation and properties of semifluorinated block copolymers of 2-(dimethylamino)ethyl methacrylate and fluorooctyl methacrylates

Semifluorinated block copolymers of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(fluorooctyl methacrylates) (PFOMA) were prepared using group transfer polymerisation via sequential monomer addition. Wide ranges of copolymers were obtained with good control over both molecular weight and composition by adjusting the monomers/initiator ratio. The micellar characteristics of the copolymers in water and chloroform were investigated by quasi-elastic light scattering and transmission electron microscopy. The size and morphologies of micelles were greatly influenced by copolymer composition, pH, and temperature. In addition, the solubility of copolymers and the formation of water-in-carbon dioxide (W/C) microemulsions were described in terms of the cloud points. The block copolymers exhibited the excellent ability of stabilizing W/C microemulsions.     

pH- and temperature-responsive amphiphilic diblock copolymers of 4-vinylpyridine and oligoethyleneglycol methacrylate synthesized by RAFT polymerization

Diblock copolymers of 4-vinylpyridine (4VP) and oligoethyleneglycol methyl ether methacrylate (OEGMA) were synthesized for the first time using RAFT polymerization technique as potential drug delivery systems. Effects of the number of ethylene glycol units in OEGMA, chain length of hydrophobic P4VP block, pH, concentration and temperature on the solution behavior of the copolymers were investigated comprehensively. Copolymer chains formed micelles at pH values higher than 5 whereas unimeric polymers were observed to exist below pH 5, owing to the repulsion between positively charged P4VP blocks. The size of the micelles was dependent on the relative length of blocks, P4VP and POEGMA. Thermo-responsive properties of copolymers were investigated depending on the pH and length of P4VP block. The increase in the length of P4VP block decreased the LCST substantially at pH 7. At pH 3, LCST of copolymers shifted to higher temperatures due to the increased interaction of copolymers with water through positively charged P4VP block.     

Synthesis,morphology and properties of poly(dimethylsiloxane)/poly(n-butyl acrylate) mixed soft block-based copolymers: A new class of thermoplastic elastomer

Design, synthesis, morphology, mechanical properties and in vitro oxidative stability of new class of surface modified thermoplastic elastomers containing mixed soft rubbery poly(n-butyl acrylate-b-dimethylsiloxane-b-n-butyl acrylate) (PnBA-b-PDMS-b-PnBA) block and glassy poly methyl methacrylate (PMMA) end blocks have been reported. Thus well-defined pentablock copolymers such as PMMA-b-PnBA-b-PDMS-b-PnBA-b-PMMA were synthesized by Atom Transfer Radical Polymerization (ATRP). Moderate amount of PDMS (8–15 wt%) in the copolymers significantly enhances the oxidative stability of the surface and contact angle of water in compare to neat PMMA-b-PnBA-b-PMMA copolymer. The phase morphology of such type of copolymers was studied in detailed which suggests that the mixed soft PnBA-b-PDMS-b-PnBA part forms single phase and the degree of phase separation between PnBA-b-PDMS-b-PnBA and PMMA in PMMA-b-PnBA-b-PDMS-b-PnBA-b-PMMA copolymer is higher than the degree of phase separation between PnBA and PMMA in PnBA-b-PDMS-b-PnBA copolymer. This approach of surface modification was extended to synthesize PMMA-b-PLMA-b-PDMS-b-PLMA-b-PMMA (PLMA = polylauryl methacrylate) block copolymers with improved surface properties.     

Synthesis and Characterization of Block-Graft Copolymers [poly(epichlorohydrin-<Emphasis Type="Italic">b</Emphasis>-styrene)-<Emphasis Type="Italic">g</Emphasis>-poly(methyl methacrylate)] by Combination of Activated Monomer Polymerization,NMP and ATRP

Summary Synthesis of block-graft copolymers, namely poly(epichlorohydrin-b-styrene)-g-poly(methyl methacrylate) (PECH-b-St)-g-PMMA) by combination of Activated Monomer (AM), Nitroxide Mediated Polymerization (NMP) and Atom Transfer Radical Polymerization (ATRP) methods was described. For this purpose, first epichlorohydrin (ECH) was polymerized by using BF₃THF complex in the presence of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyl-1-oxy (HTEMPO) via AM mechanism. The resulting stable radical terminated polymer was subsequently used as a counter radical in the NMP of styrene (St) initiated by benzoyl peroxide to yield block copolymers of ECH and St. Finally, the ATRP of methyl methacrylate (MMA) by using chloromethyl groups of the PECH segment as initiating sites resulted in the formation of (PECH-b-St)-g-PMMA). The structures of the intermediate polymers at various stages were characterized by ¹H-NMR spectral investigations. The thermal behavior and surface morphology of the copolymers were also investigated by DSC and AFM measurements.     

Synthesis and characterization of sulfonated fluorinated block copolymer membranes with different esterified initiators for DMFC applications

This investigation studied the synthesis of ionic membranes composed of a sulfonated poly(styrene‐isobutylene‐styrene) with novel fluoroblock copolymers. These fluoroblock copolymers were synthesized using three different initiators by Atom Transfer Radical Polymerization (ATRP); two fluoroinitiators were obtained from the esterification of 2‐(perfluoroalkyl) ethanol or octafluoro 4‐4′‐biphenol. The third initiator evaluated was 1‐bromoethyl benzene. The resulting block copolymers were characterized using several techniques: Gel Permeation Chromatography, Nuclear Magnetic Resonance, Fourier Transform Infrared Spectroscopy, Ultraviolet Spectroscopy, Thermogravimetric Analysis, and Differential Scanning Calorimetry. Transport properties (e.g., proton conductivity and methanol permeability) were measured to evaluate their performance for direct methanol fuel cell (DMFC). The choice of ATRP initiator was found to have a profound impact on the thermal stability of the different homopolymers and block copolymers studied. In addition, the chemical nature and symmetry of the initiators can lead to different chemical and electronic transitions, which influence the performance of these ionic membranes in applications such as proton exchange membranes for DMFC applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42046.     

Influence of the copolymer architecture and composition on the response and mechanical properties of pH‐sensitive fibers

A series of copolymers based on acrylonitrile (AN) and acrylic acid (AA) with varying architecture and composition were synthesized using free radical polymerization. The distribution of monomers in the copolymer chains could be successfully controlled by regulating the addition of more reactive monomer (AA). Copolymers having nearly random distribution of comonomer moieties to block type distribution with different composition (10–50 mol % AA) were synthesized to investigate the effect of polymer architecture and composition on pH response and mechanical properties of resultant structures. These copolymers were solution spun from dimethylformamide‐water system, drawn in coagulation bath, and annealed at 120°C for 2 h to make pH‐sensitive fibers which were structurally stable without the need of chemical crosslinking. The fibers from block copolymers showed significantly better tensile strength (34.3 MPa), higher retractive forces (0.26 MPa), and enhanced pH response (swelling 3890%) in comparison with fibers from random copolymer (13.55 MPa, 0.058 MPa, and 1723%, respectively). The tensile strength and retractive forces could be further improved to a value of 72 MPa and 0.36 MPa, respectively, by changing the composition of the block copolymer while retaining the swelling percentage similar to the random copolymer mentioned above. It is proposed that on processing to fibers, the block copolymers could form a segregated domain structure with separate domains of AA and AN, where AN domains were responsible for high structural integrity by providing connectivity among polymer chains, while AA domains showed improved response to changing pH of the environment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007