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Polymerization-induced self-assembly and disassembly during the synthesis of thermoresponsive ABC triblock copolymer nano-objects in aqueous solution
Chemical Science ( IF 7.6 ) Pub Date : 2022-06-08 , DOI: 10.1039/d2sc01611g
Spyridon Varlas 1 , Thomas J Neal 1 , Steven P Armes 1
Affiliation  

Polymerization-induced self-assembly (PISA) has been widely utilized as a powerful methodology for the preparation of various self-assembled AB diblock copolymer nano-objects in aqueous media. Moreover, it is well-documented that chain extension of AB diblock copolymer vesicles using a range of hydrophobic monomers via seeded RAFT aqueous emulsion polymerization produces framboidal ABC triblock copolymer vesicles with adjustable surface roughness owing to microphase separation between the two enthalpically incompatible hydrophobic blocks located within their membranes. However, the utilization of hydrophilic monomers for the chain extension of linear diblock copolymer vesicles has yet to be thoroughly explored; this omission is addressed for aqueous PISA formulations in the present study. Herein poly(glycerol monomethacrylate)-poly(2-hydroxypropyl methacrylate) (G-H) vesicles were used as seeds for the RAFT aqueous dispersion polymerization of oligo(ethylene glycol) methyl ether methacrylate (OEGMA). Interestingly, this led to polymerization-induced disassembly (PIDA), with the initial precursor vesicles being converted into lower-order worms or spheres depending on the target mean degree of polymerization (DP) for the corona-forming POEGMA block. Moreover, construction of a pseudo-phase diagram revealed an unexpected copolymer concentration dependence for this PIDA formulation. Previously, we reported that PHPMA-based diblock copolymer nano-objects only exhibit thermoresponsive behavior over a relatively narrow range of compositions and DPs (see Warren et al., Macromolecules, 2018, 51, 8357–8371). However, introduction of the POEGMA coronal block produced thermoresponsive ABC triblock nano-objects even when the precursor G-H diblock copolymer vesicles proved to be thermally unresponsive. Thus, this new approach is expected to enable the rational design of new nano-objects with tunable composition, copolymer architectures and stimulus-responsive behavior.

中文翻译:

水溶液中热响应ABC三嵌段共聚物纳米物体合成过程中聚合诱导的自组装和解组装

聚合诱导自组装 (PISA) 已被广泛用作在水介质中制备各种自组装 AB 二嵌段共聚物纳米物体的有力方法。此外,有充分证据表明,通过种子 RAFT 水乳液聚合使用一系列疏水单体进行 AB 二嵌段共聚物囊泡的扩链产生了具有可调节表面粗糙度的框架形ABC 三嵌段共聚物囊泡,这是由于位于内部的两个焓不相容的疏水嵌段之间的微相分离。他们的膜。然而,亲水性的利用用于线性二嵌段共聚物囊泡扩链的单体还有待深入探索;在本研究中,这一遗漏适用于水性 PISA 制剂。本文将聚(单甲基丙烯酸甘油酯)-聚(甲基丙烯酸 2-羟丙酯)(GH)囊泡用作低聚(乙二醇)甲基醚甲基丙烯酸酯(OEGMA)的 RAFT 水分散聚合的种子。有趣的是,这导致了聚合诱导的拆卸(PIDA),根据形成电晕的 POEGMA 块的目标平均聚合度 (DP),将初始前体囊泡转化为低阶蠕虫或球体。此外,假相图的构建揭示了这种 PIDA 配方出乎意料的共聚物浓度依赖性。之前,我们报道了基于 PHPMA 的二嵌段共聚物纳米物体仅在相对狭窄的组成和 DP 范围内表现出热响应行为(参见 Warren等人Macromolecules2018,51, 8357–8371)。然而,即使前体 GH 二嵌段共聚物囊泡被证明对热无响应,POEGMA 冠状嵌段的引入也产生了热响应性 ABC 三嵌段纳米物体。因此,这种新方法有望实现对具有可调成分、共聚物结构和刺激响应行为的新型纳米物体的合理设计。
更新日期:2022-06-08
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