Das Anindita, Petkau-Milroy Katja, Klerks Gilian, van Genabeek Bas, Lafleur René P M, Palmans Anja R A, Meijer E W
Institute for Complex Molecular Systems and Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands.
ACS Macro Lett. 2018 May 15;7(5):546-550. doi: 10.1021/acsmacrolett.8b00168. Epub 2018 Apr 16.
Intriguingly, little is known about the impact of dispersity on the crystallization driven self-assembly (CDSA) of amphiphilic block copolymers in aqueous media. Here, we investigate the influence of dispersity on the CDSA of ABA-type amphiphilic block co-oligomers (ABCOs). Two pairs of ABCOs are synthesized comprising discrete ( = 1.00) or disperse ( = 1.20) isotactic l-lactic acid 16-mers as the semicrystalline hydrophobic block and either oligo(ethylene glycol) methyl ether (MeOoEG) or oligo(tetraethylene glycol succinate) (oTEGSuc) as the discrete hydrophilic block. Self-assembly studies in water with 10% THF reveal uniform nanofibers/2D sheets for the discrete oligomers, but such structural regularity is largely compromised in the disperse oligomers. The results are corroborated by sharp melting transitions in both solution and bulk for the discrete ABCOs, unlike their disperse analogues that show a lack of crystallization. Interestingly, the discrete MeOoEG-LLA oligomer reveals crystallization driven gelation, illustrating the contrasting differences between the discrete oligomers and their disperse counterparts.
有趣的是，关于分散度对两亲性嵌段共聚物在水性介质中结晶驱动自组装（CDSA）的影响，人们所知甚少。在此，我们研究了分散度对ABA型两亲性嵌段共低聚物（ABCOs）的CDSA的影响。合成了两对ABCOs，其中包括作为半结晶疏水嵌段的离散（Đ = 1.00）或分散（Đ = 1.20）的全同立构l-乳酸16聚体，以及作为离散亲水嵌段的聚乙二醇甲醚（MeOoEG）或聚丁二酸四乙二醇酯（oTEGSuc）。在含有10%四氢呋喃的水中进行的自组装研究表明，离散低聚物形成了均匀的纳米纤维/二维片层，但这种结构规整性在分散低聚物中受到了很大损害。离散ABCOs在溶液和本体中都有明显的熔融转变，这证实了上述结果，而它们的分散类似物则缺乏结晶现象。有趣的是，离散的MeOoEG-LLA低聚物表现出结晶驱动的凝胶化，说明了离散低聚物与其分散对应物之间的显著差异。
