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Synthesis and Self-Assembly of ABn Miktoarm Star Polymers
ACS Macro Letters ( IF 5.1 ) Pub Date : 2020-02-27 , DOI: 10.1021/acsmacrolett.0c00061
Morgan W Bates , Stephanie M Barbon , Adam E Levi , Ronald M Lewis 1 , Haley K Beech 1 , Kasper M Vonk , Cheng Zhang , Glenn H Fredrickson , Craig J Hawker , Christopher M Bates
Affiliation  

The stability of tetrahedrally close-packed (TCP) phases in block copolymer melts is predicted by theory to depend on molecular architecture, yet no experimental studies to date have probed its effect. Motivated by this open question, here we report an efficient synthesis of asymmetric ABn miktoarm star polymers using functionalized sugars as cores for orthogonal grafting-from block copolymerizations. A combination of ring-opening and atom transfer radical polymerization produced model low dispersity materials comprising a single A = poly(lactide) (L) and multiple B = poly(dodecyl acrylate) (D) arms that amplify “conformational asymmetry” through two concerted effects: the mikto architecture and disparate block statistical segment lengths. Analyzing the self-assembly of LD2 and LD3 samples resulted in the discovery of two TCP phases, σ and A15, that remained stable to significantly higher A-block volume fractions as the number of B arms increased. These results experimentally establish the importance of conformational asymmetry and molecular architecture as powerful design tools for the self-assembly of block copolymers into nonclassical phases.

中文翻译:

ABn Miktoarm 星形聚合物的合成与自组装

理论上预测嵌段共聚物熔体中四面体密堆积 (TC​​P) 相的稳定性取决于分子结构,但迄今为止还没有实验研究探讨其影响。受这个悬而未决的问题的启发,我们在此报告了一种使用功能化糖作为正交接枝嵌段共聚核心的不对称 AB n miktoarm 星形聚合物的有效合成。开环和原子转移自由基聚合的组合产生了模型低分散材料,包括单个 A = 聚(丙交酯)(L)和多个 B = 聚(丙烯酸十二烷基酯)(D)臂,通过两个协同作用放大“构象不对称”效果:mikto 架构和不同的块统计段长度。分析 LD 2和 LD的自组装3 个样品导致发现了两个 TCP 相 σ 和 A15,随着 B 臂数量的增加,它们保持稳定到显着更高的 A 块体积分数。这些结果通过实验证明了构象不对称和分子结构作为将嵌段共聚物自组装成非经典相的强大设计工具的重要性。
更新日期:2020-02-28
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