Vitrimers based on block copolymers give access to adaptable polymer networks where the resulting properties can be adjusted not only by the vitrimer chemistry itself but also can be influenced by the structure of the block copolymer. In this work, linear AB, ABA, and BAB block copolymers are introduced as backbones in vinylogous urethane vitrimers to produce crosslinked materials that are reprocessable and have a wide range of tunable mechanical properties. The narrow-disperse block copolymers were synthesized by photoiniferter reversible addition-fragmentation chain transfer polymerization (photoRAFT). Two different types of hydrophobic A blocks, poly(methyl methacrylate) and poly(ethyl methacrylate) with a higher glass transition temperature compared to the hydrophilic B block, poly(2-hydroxyethyl methacrylate), were chosen. The B block carries the functional groups for further modification to obtain acetoacetylated side groups, which are then transformed to vinylogous urethane crosslinks. It has been found that the architectures of backbones as well as the alkyl substituents in the side groups of the A block influence the final performance of the vitrimers. By adjusting block sequences, the mechanical properties can be varied from hard to tough to elastic materials corresponding to BAB, ABA, and AB block copolymer vitrimers, respectively. These materials are reprocessable and have self-healing as well as shape-memory properties.

中文翻译：

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基于具有不同嵌段序列的嵌段共聚物的 Vitrimer


基于嵌段共聚物的 Vitrimer 可以形成适应性强的聚合物网络，其中所产生的性能不仅可以通过 Vitrimer 化学本身进行调节，还可以受到嵌段共聚物结构的影响。在这项工作中，线性 AB、ABA 和 BAB 嵌段共聚物被引入插烯聚氨酯玻璃体中作为主链，以生产可再加工且具有广泛可调机械性能的交联材料。通过光引发剂可逆加成-断裂链转移聚合（photoRAFT）合成了窄分散嵌段共聚物。选择了两种不同类型的疏水性 A 嵌段：聚（甲基丙烯酸甲酯）和聚（甲基丙烯酸乙酯），与亲水性 B 嵌段（聚（甲基丙烯酸 2-羟乙酯））相比，它们具有更高的玻璃化转变温度。 B嵌段带有官能团，用于进一步改性以获得乙酰乙酰化侧基，然后将其转化为插烯氨基甲酸酯交联键。已经发现主链的结构以及A嵌段侧基中的烷基取代基影响vitrimer的最终性能。通过调整嵌段序列，机械性能可以从坚硬到坚韧再到弹性材料变化，分别对应于 BAB、ABA 和 AB 嵌段共聚物 vitrimer。这些材料可再加工，具有自我修复和形状记忆特性。