Photoinduced Synthesis of α,ω-Telechelic Sequence-Controlled Multiblock Copolymers
Photoinduced Synthesis of α,ω-Telechelic Sequence-Controlled Multiblock Copolymers
复制标题
DOI：
10.1021/acs.macromol.5b00058
复制
发表时间：
2015-03-10
期刊：
影响因子：
5.5
通讯作者：
Haddleton, David M.
中科院分区：
文献类型：
--
作者：
Anastasaki, Athina;Nikolaou, Vasiliki;Haddleton, David M.
光诱导活性自由基聚合已被用于合成一系列丙烯酸类单体的α，ω-遥爪多嵌段共聚物，所述丙烯酸类单体包括丙烯酸甲酯（MA）、丙烯酸乙酯（EA）、乙二醇甲醚丙烯酸酯（EGA）和丙酮缩醇丙烯酸酯（SA）。在仔细优化的条件下，获得了良好限定的三嵌段（23嵌段）共聚物（（D）/bar = 1.18），在所有重复的单体添加中实现了高转化率（>98%）。重要的是，发现降低的温度（15 ° C）导致观察到的分散性降低（1.14对1.45），这与采用较高温度（50 ° C）时相反。采用了许多双官能引发剂，包括亚乙基双（2-溴异丁酸酯）（EbBiB）、PEG引发剂（平均M-w = 1000 g mol（-1））和双[2-（2 '-溴异丁酰氧基）乙基]二硫化物（（BiBOE）2S 2），得到了各种分子量的窄分散的多嵌段共聚物（DPn类似于2/13/50/100/嵌段）。令人印象深刻的是，还合成了高分子量十一嵌段（11嵌段）共聚物，其M-n = 150 000 g mol（-1），（D）/bar = 1.22。为了证明所得到的遥爪材料的对称性，（13个嵌段，（D）/bar = 1.18，M-n = 25 000 g mol（-1））是利用双官能二硫化物引发剂合成的，该引发剂在聚合后裂解，得到分子量为母体聚合物一半的窄分散聚合物（（D）/bar = 1.10，M-n = 12 400 g mol（-1））。
Photoinduced living radical polymerization has been employed to synthesize alpha,omega-telechelic multiblock copolymers of a range of acrylic monomers including methyl acrylate (MA), ethyl acrylate (EA), ethylene glycol methyl ether acrylate (EGA), and solketal acrylate (SA). Under carefully optimized conditions, a well-defined tricosablock (23 blocks) copolymer was obtained ((D) over bar = 1.18) with high conversion (>98%) achieved throughout all the iterative monomer additions. Crucially, a reduced temperature (15 degrees C) was found to result in an observed decrease in the dispersities (1.14 vs 1.45) as opposed to when higher temperatures (50 degrees C) were employed. A number of bifunctional initiators were employed, including ethylene bis(2-bromoisobutyrate) (EbBiB), a PEG initiator (average M-w = 1000 g mol(-1)), and bis[2-(2'-bromoisobutyryloxy)ethyl] disulfide ((BiBOE)2S2), resulting in narrow dispersed multiblock copolymers in various molecular weights (DPn similar to 2/13/50/100 per block). Impressively, a high molecular weight undecablock (11 blocks) copolymer of M-n = 150 000 g mol(-1) and (D) over bar = 1.22 was also synthesized. In order to demonstrate the symmetry of the resulting telechelic materials, a well-defined tridecablock (13 blocks, (D) over bar = 1.18, M-n = 25 000 g mol(-1)) was synthesized utilizing a bifunctional disulfide initiator which was cleaved postpolymerization, yielding a narrow disperse polymer at half the molecular weight of the parent polymer ((D) over bar = 1.10, M-n = 12 400 g mol(-1)).