非线形嵌段共聚物的合成

主要介绍了非线形嵌段共聚物,如星型嵌段共聚物、杂臂星型共聚物、梳型聚合物等的合成方法,包括多官能团引发剂法、大分子引发剂法等。各种活性聚合方法,如阳离子开环聚合、原子转移自由基聚合(ATRP)和氮氧稳定自由基聚合等都可以用于合成非线形嵌段共聚物。     

基于ATRP技术的多嵌段共聚物研究进展

原子转移自由基聚合(ATRP)技术是合成结构规整性聚合物的有效途径。综述了近十年来采用ATRP技术合成多嵌段共聚物的研究进展。从引发剂、共聚单体和反应条件等方面讨论了ABA型、ABC型和ABCBA型等类型多嵌段共聚物的合成、性质与潜在应用。对原子转移自由基聚合技术在合成功能性多嵌段共聚物中的应用前景进行了展望。     

支化PEG-b-PCL嵌段共聚合物的合成

以聚乙二醇甲基丙烯酸酯(PEGMA)为大分子引发剂进行ε-己内酯的酶催化开环聚合, 合成出嵌段共聚物, 然后将其转化成大分子引发剂型单体(Macroinimer), 最后通过原子转移自由基聚合(ATRP)制备出一种新型结构的嵌段型支化聚合物.     

用大分子引发剂法制备嵌段共聚物

主要介绍了用大分子引发剂法制备嵌段共聚物的方法。大分子引发剂是从已商品化的功能聚合物制得或用其它活性聚合方法合成。从单封端的端羟基聚合物、其它单官能团或双官能团聚合物以及双功能基团缩聚物制得大分子引发剂．然后用于原子转移自由基聚合(ATRP)、氮氧稳定自由基聚合以及可逆加成裂解链转移(RAFT)聚合等．可制得结构可控、分子量分布窄的嵌段共聚物。     

水分散体系中甲基丙烯酸甲酯和丙烯酸八氟戊酯嵌段共聚物的合成与表征

在聚合物链上引入氟元素可以赋予聚合物很多优异的性能 ,如良好的热稳定性、化学稳定性、生物相容性和憎水憎油性等 .含氟单体与一般单体共聚是合成含氟共聚物的重要途径 .通过原子转移自由基聚合 (ATRP)不仅可以实现多种单体的控制 (共 )聚合 ,而且可以合成出具有预定分子量、窄分子量分布以及结构明晰聚合物[1] ,我们曾报道了溶液体系中用ATRP方法合成含氟嵌段共聚物[2～ 4] .众所周知 ,大多数含氟聚合物都是通过乳液或悬浮聚合反应合成的 .然而 ,普通的乳液或悬浮聚合难以合成结构和组成可控的聚合物 ,如嵌段共聚物 ,所以近年来 ,水…     

化学酶法合成五嵌段聚合物及其自组装行为的研究

用酶促开环聚合与ATRP方法相结合,制备了聚甲基丙烯酸六氟丁酯-聚己内酯-聚乙二醇-聚己内酯-聚甲基丙烯酸六氟丁酯(PHFMA-b-PCL-b-PEG-b-PCL-b-PHFMA)五嵌段聚合物.首先用Novozym e 435作为催化剂合成了聚己内酯-聚乙二醇-聚己内酯三嵌段聚合物,然后通过端基官能化法合成了大分子引发剂,并用其引发甲基丙烯酸六氟丁酯(HFMA)的ATRP反应,合成了五嵌段聚合物.通过核磁和GPC证明了大分子引发剂和五嵌段共聚物的结构,五嵌段共聚物的GPC分析表明这种合成方法的可行.共聚物胶束的直径和大小通过动态光散射方法和原子力显微镜测试,五嵌段共聚物在水中的的自组装行为也被研究.结果证明胶束是球形,其平均直径为77 nm.聚合物在四氢呋喃中的浓度对聚合物的聚集形貌有很大的影响.     

“活”的α-甲基苯乙烯共聚物:聚合反应新化学和材料工程新技术

高于临界聚合反应温度时,α-甲基苯乙烯(AMS)单体和其聚合物处于聚合-解聚平衡.基于AMS聚合物在受热时可裂解生成大分子链自由基的特性,提出了含AMS结构单元的共聚物是一种"活"的,可作为大分子自由基引发剂的概念,并通过实验对AMS共聚物的引发性能和应用进行了研究.首先,合成了AMS与(甲基)丙烯酸酯类单体、丙烯酸、苯乙烯和马来酸酐等的共聚物.然后以上述共聚物为大分子引发剂,在90℃引发(甲基)丙烯酸酯类单体和苯乙烯等的本体聚合、溶液聚合和乳液聚合,得到了嵌段共聚物.用ESR谱证明了AMS的共聚物在加热时能裂解生成以碳原子为中心的大分子链自由基.此外,在聚合物的熔融共混中,AMS分解产生的大分子链自由基通过偶合反应形成接枝链,原位生成相容剂.AMS共聚物还可以对碳纳米管及无机粒子进行表面原位接枝改性.AMS共聚物是一类无小分子残留的绿色自由基引发剂,可以用于低成本制备两嵌段共聚物,也可以用于聚合物的熔融共混增容.     

两亲性PS-b-PEG嵌段共聚物刷的合成及响应行为

利用原子转移自由基聚合(ATRP)和点击化学(Click)反应, 在硅基底上制备了聚苯乙烯-b-聚乙二醇(PS-b-PEG)两亲性嵌段共聚物刷. 首先, 利用ATRP方法在表面改性的硅片引发苯乙烯单体(St)的聚合, 得到PS-Br均聚刷, 然后通过叠氮化钠(NaN₃)将均聚刷末端功能化为PS-N₃, 再与炔基聚乙二醇甲醚(Alkynyl-PEG)发生Click反应, 得到PS-b-PEG嵌段共聚物刷. 通过X射线光电子能谱(XPS)和接触角测量仪表征了聚合物刷的表面化学组成和表面亲疏水性质, 证明在硅基底上接枝了嵌段共聚物刷. 用原子力显微镜(AFM)观察了PS-b-PEG嵌段共聚物刷在不同溶剂处理后的形态结构变化, 研究了其响应行为.     

原子转移自由基聚合方法在纤维素及其衍生物改性方面的应用Ⅰ

原子转移自由基聚合反应(atom transfer radical polymerization,ATRP)是一种活性/可控的自由基聚合反应,是大分子设计的有效工具,利用ATRP可以合成各种组成和结构的聚合物,如均聚物、嵌段共聚物、梯度共聚物、接枝共聚物、星状聚合物、超支化聚合物等.近年来,ATBP还被用于纤维素及其衍生物的修饰改性.该方法解决了传统自由基接枝改性方法中存在的问题,不仅可以保持纤维素骨架的完整性,还可以得到不包含均聚物的纯接枝共聚物,而且接枝链的长度及分子量分布均可控.本文介绍了原子转移自由基聚合方法在纤维素及其衍生物改性方面的应用.     

基于苯氧基联烯的两亲性嵌段共聚物的合成

运用机理转换策略,结合自由基聚合和原子转移自由基聚合(ATRP),制备了含有聚联烯链段的两亲性三嵌段共聚物.设计合成了含有偶氮和ATRP引发基团的双官能团引发剂,先用该双官能团引发剂引发苯氧基联烯单体的自由基聚合,得到了含有ATRP引发基团的聚联烯大分子引发剂,然后该大分子引发剂引发亲水性单体N,N-二乙基氨乙基甲基丙烯酸酯(DEAEMA)的ATRP聚合,制得了聚N,N-二乙基氨乙基甲基丙烯酸酯-聚联烯-聚N,N-二乙基氨乙基甲基丙烯酸酯(PDEAEMA-b-PPOA-b-PDEAEMA).该三嵌段共聚物能在水溶液中形成胶束,通过荧光探针技术分别测定了它在不同离子浓度、不同p H值条件下的临界胶束浓度.实验结果表明,该聚合物胶束的cmc随着p H值增大而减小,随着离子浓度的增大而增大.     

Synthesis of Block Copolymers by Combination of Atom Transfer Radical Polymerization and Visible Light‐Induced Free Radical Promoted Cationic Polymerization

A new synthetic approach for the preparation of block copolymers by mechanistic transformation from atom transfer radical polymerization (ATRP) to visible light‐induced free radical promoted cationic polymerization is described. A series of halide end‐functionalized polystyrenes with different molecular weights synthesized by ATRP were utilized as macro‐coinitiators in dimanganese decacarbonyl [Mn₂(CO)₁₀] mediated free radical promoted cationic photopolymerization of cyclohexene oxide or isobutyl vinyl ether. Precursor polymers and corresponding block copolymers were characterized by spectral, chromatographic, and thermal analyses.     

Preparation of homopolymers and block copolymers in miniemulsion by ATRP using activators generated by electron transfer (AGET)

A new initiating/catalytic system for atom transfer radical polymerization (ATRP) is reported. This system starts with alkyl halides as initiators and transition metal complexes in their oxidatively stable state (e.g., Cu(II)Br2/ligand) as catalysts. The activators are generated by electron transfer (AGET) without involvement of initiating organic radicals. AGET ATRP has a significant advantage over simultaneous reverse and normal initiation (SR&NI) ATRP, because it provides a simple route for synthesizing pure polymers with complex architectures such as star copolymers, block copolymers, etc. Furthermore, AGET ATRP can be also successfully carried out in miniemulsion. Homopolymers and pure block copolymers were successfully synthesized via ATRP in miniemulsion using AGET ATRP. The final products were analyzed via two-dimensional chromatography, which combines high performance liquid chromatography (HPLC) and gel permeation chromatography (GPC). The resulting chromatograms showed that pure linear block copolymers and star block copolymers were prepared without the presence of any homopolymers.     

Amphiphilic well-defined degradable star block copolymers by combination of ring-opening polymerization and atom transfer radical polymerization: Synthesis and application as drug delivery carriers

Atom transfer radical polymerization (ATRP) is one of the most popular advanced polymerization techniques in macromolecular science, allowing the synthesis of tailor-made polymers with controlled molecular weight, architecture, composition, and functionality. The combination of ATRP and ring-opening polymerization (ROP) provides a straightforward route for the preparation of polymers exhibiting both targeted and well-defined features and biodegradability, which is very interesting for the development of new materials for biomedical applications. Among the different types of polymer architectures, amphiphilic star block copolymers (BCPs) represent a very attractive one, due to their high degree of functionality at the molecular surface, low hydrodynamic volume and higher encapsulation ability, compared to molecular systems based on linear polymers. This review article highlights the research focused on the synthesis of amphiphilic well-defined degradable star BCPs by combination of ROP and ATRP, with particular focus on the development of polymers for biomedical applications, such as anticancer drug delivery, diagnosis therapy, or photodynamic therapy, which is the most investigated field regarding these polymers.     

Chemoenzymatic Synthesis of Branched Polymers

Summary: The combination of enzymatic polymerization with ATRP for the synthesis of branched (block) copolymers was investigated. Heterotelechelic polycaprolactone macroinimer was synthesized in a one‐pot enzymatic procedure by using 2‐hydroxyethyl α‐bromoisobutyrate as a bifunctional initiator. A polymerizable end group was introduced by subsequent in situ enzymatic acrylation with vinyl acrylate. Branched polymers were obtained by subsequent atom transfer radical polymerization (ATRP).

Enzymatic synthesis of heterotelechelic macromonomers and subsequent self condensing vinyl polymerization by ATRP.     

原子转移自由基聚合及可控自由基聚合

以作者在原子转移自由基聚合领域的研究成果为主导,结合国内外文献,对近年来出现的颇具影响的可控自由基聚合体系与进行了评述与展望。     

Block copolymerization of 5,6-benzo-2-methylene-1,3-dioxepane with conventional vinyl monomers by ATRP method

Polystyrene-block-poly(5,6-benzo-2-methylene-1,3-dioxepane) (PSt-b-PBMDO), poly(methyl methacrylate)-block-PBMDO (PMMA-b-PBMDO) and poly(methyl acrylate)-block-PBMDO (PMA-b-PBMDO) were synthesized by two-step atom transfer radical polymerization (ATRP) of conventional vinyl monomers, then BMDO. First, the polymerization of St, or MMA, or MA was realized by ATRP with ethyl α-bromobutyrate (EBrB) as initiator in conjunction with CuBr and 2,2^′-bipyridine (bpy). After isolation, polymers with terminal bromine, PSt-Br, PMMA-Br and PMA-Br, were obtained. Second, the ATRP of BMDO was performed by using macroinitiator, PSt-Br (or PMMA-Br, PMA-Br) in the presence of CuBr/bpy. The structures of block copolymers were characterized by 1H NMR spectra. Molecular weight and polydispersity index were determined on gel permeation chromatograph. Among the block copolymers obtained, PMA-b-PBMDO shows the most narrow molecular weight distribution.     

ABA triblock copolymers from two mechanistic techniques: Polycondensation and atom transfer radical polymerization

ABA triblock copolymers were synthesized using two polymerization techniques, polycondensation, and atom transfer radical polymerization (ATRP). A telechelic polymer was synthesized via polycondensation, which was then functionalized into a difunctional ATRP initiator. Under ATRP conditions, outer blocks were polymerized to form the ABA triblock copolymer. Six types of samples were prepared based on a poly(ether ether ketone) or poly(arylene ether sulfone) center block with either poly(methyl methacrylate), poly(pentafluorostyrene), or poly(ionic liquid) outer blocks. As polycondensation results in polymers with broad molecular weight distribution (MWD), the center of these triblock copolymers are disperse, while the outside blocks have narrow MWD due to the control afforded from ATRP. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 228–238     

ATRP法合成含氟丙烯酸酯类聚合物的研究进展

含氟丙烯酸酯聚合物由于氟原子的改性作用而具有优异的表面特性,不仅稳定,具有很好的耐氧化和耐腐蚀性,而且具有较好的耐水、耐油及耐污性,可望在新材料的开发、理论研究和实际应用等方面获得广泛的应用.而原子转移自由基聚合(ATRP)又可为分子设计和合成提供很有效的途径,利用这种聚合可以获得预期结构和性能的含氟嵌段聚合物材料,充分发挥含氟元素的改性作用.本文综述了ATRP在丙烯酸氟烷基酯聚合物合成方面的应用,并介绍了国内外在此领域的研究状况.