Based on the highly disparate reactivities of isoprene (I, r_I = 25.4) and 4-methylstyrene (4MS, r_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)_n type with up to 10 blocks. All multiblock copolymers showed narrow molecular weight distributions (dispersity Đ = 1.04–1.12). High molecular weights in the range of 80 to 400 kg mol^–1 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, T_g) and flexible (low T_g) chains, in n/2 steps, while keeping overall dispersity low.

中文翻译：

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阴离子共聚使具有高分子量的交替 (AB)n 多嵌段共聚物在 n/2 步中的可扩展合成成为可能

基于异戊二烯 (I, r _I = 25.4) 和 4-甲基苯乙烯 (4MS, r _4MS = 0.007) 在非极性介质中的阴离子共聚反应的高度不同的反应性，快速且可扩展地合成递变多嵌段共聚物的一般策略已经形成了一个非常陡峭的梯度。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递减的二嵌段，从而获得具有多达 10 个嵌段的 (AB) _n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）。^{80 至 400 kg mol –1}范围内的高分子量实现了。由于 PI 和 P4MS 链段的不相容性，多嵌段共聚物表现出纳米相分离，表现为两种成分的单独玻璃化转变。应力-应变测量显示出非凡的韧性和高达 1150% 的断裂伸长率，即使在 50/50 的摩尔比 I/4MS（即 37 wt% 异戊二烯）下也是如此。我们的合成允许在n /2 步中获得具有刚性（P4MS，高玻璃化转变， T _g）和柔性（低T _g）链的各种锥形多嵌段共聚物结构，同时保持较低的整体分散度。