Grune Eduard, Appold Michael, Müller Axel H E, Gallei Markus, Frey Holger
Institute of Organic Chemistry, Johannes Gutenberg University, Duesbergweg 10-14, 55128 Mainz, Germany.
Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128, Mainz, Germany.
ACS Macro Lett. 2018 Jul 17;7(7):807-810. doi: 10.1021/acsmacrolett.8b00390. Epub 2018 Jun 22.
Based on the highly disparate reactivities of isoprene (I, = 25.4) and 4-methylstyrene (4MS, = 0.007) in the anionic copolymerization in nonpolar media, a general strategy for the rapid and scalable synthesis of tapered multiblock copolymers with an extremely steep gradient has been developed. A repetitive addition strategy of a mixture of isoprene and 4MS leads to a tapered diblock in each case, giving access to linear alternating multiblock copolymers of the (AB) type with up to 10 blocks. All multiblock copolymers showed narrow molecular weight distributions (dispersity = 1.04-1.12). High molecular weights in the range of 80 to 400 kg mol were achieved. Due to the incompatibility of PI and P4MS segments, the multiblock copolymers exhibit nanophase separation, manifested by separate glass transitions for both constituents. Stress-strain measurements revealed extraordinary toughness and elongations up to 1150% strain at break, even at a 50/50 molar ratio I/4MS (i.e., 37 wt% isoprene). Our synthesis permits access to a wide range of tapered multiblock copolymer architectures with rigid (P4MS, high glass transition, ) and flexible (low ) chains, in /2 steps, while keeping overall dispersity low.
基于异戊二烯（I，r = 25.4）和4-甲基苯乙烯（4MS，r = 0.007）在非极性介质中阴离子共聚反应活性的巨大差异，已开发出一种快速且可扩展地合成具有极陡梯度的渐变多嵌段共聚物的通用策略。异戊二烯和4MS混合物的重复添加策略在每种情况下都会产生一个渐变二嵌段，从而获得多达10个嵌段的（AB）型线性交替多嵌段共聚物。所有多嵌段共聚物均显示出窄的分子量分布（分散度Đ = 1.04 - 1.12）。实现了80至400 kg/mol范围内的高分子量。由于PI和P4MS链段不相容，多嵌段共聚物表现出纳米相分离，表现为两种组分都有单独的玻璃化转变。应力-应变测量表明，即使在I/4MS摩尔比为50/50（即37 wt%异戊二烯）时，材料也具有非凡的韧性，断裂伸长率高达1150%。我们的合成方法能够在n/2步内获得多种具有刚性链（P4MS，高玻璃化转变温度）和柔性链（低玻璃化转变温度）的渐变多嵌段共聚物结构，同时保持总体分散度较低。
