Probing into Homopolymer Self-Assembly: How Does Hydrogen Bonding Influence Morphology?
Probing into Homopolymer Self-Assembly: How Does Hydrogen Bonding Influence Morphology?
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探究均聚物自组装：氢键如何影响形态？
DOI：
10.1021/ma302176a
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发表时间：
2013-01-08
期刊：
影响因子：
5.5
通讯作者：
Du, Jianzhong
中科院分区：
文献类型：
--
作者：
Zhu, Yunqing;Liu, Lin;Du, Jianzhong
由每个重复单元中的亲水和疏水组分组成的两亲性均聚物由于其合成比嵌段共聚物容易而在最近几年迅速发展起来。然而，有序的均聚物纳米结构是非常有限的，而对于形成小泡和其他复杂形态的固体透射电子显微镜证据是必要的，以解决均聚自组装的机制洞察。本文介绍了均聚物自组装的形态转变、结构分析和形成机理的研究进展。首先，采用可逆加成-断裂链转移(RAFT)工艺设计合成了一系列具有不同相对分子质量的两亲性均聚物--聚(2-羟基-3-苯氧丙基丙烯酸酯)(PHPPA)。其次，通过在自组装过程中简单地改变均聚物的链长或助溶剂，可以得到一系列新的基于均聚物的纳米结构，如大复合胶束(LCMs)、简单小泡、大复合小泡(LCV)和水合大复合胶束(HLCm)，这是由于均聚物自组装中聚合物间/聚合物内氢键强度不同而造成的。此外，通过预混PHPPA(36)和PHPPA(103)这两种均聚物可以形成微米级的支化圆柱体，这是PHPPA(36)和PHPPA(103)单独自组装所没有观察到的。第三，我们认为，由于均聚物的模糊疏水和亲水结构域与嵌段共聚物的不同结构域，均聚物自组装的结构与它们的嵌段共聚类似物有很大的不同。我们证实了胶束核或囊泡膜的结构(本质上彼此相似)由亲水和疏水两部分组成，这与具有疏水核或膜的嵌段共聚胶束或囊泡不同。此外，还利用染料包埋实验来识别和区分一种新的纳米结构--HLCM和LCMS。我们的研究为均聚物的自组装提供了一个新的视角。
Self-assembly of amphiphilic homopolymers composed of both hydrophilic and hydrophobic components in each repeating unit is burgeoning in recent years due to their facile synthesis compared to block copolymers. However, ordered homopolymer nanostructures are very limited, and solid TEM evidence for the formation of vesicles and other complex morphologies is necessary to address the mechanistic insights of homopolymer self-assembly. Presented in this article are the studies on the morphological transition, the structure analysis, and the formation mechanism of homopolymer self-assembly. First, a series of amphiphilic homopolymers, poly(2-hydroxy-3-phenoxypropyl acrylate) (PHPPA) with various molecular weights (MWs) have been designed and synthesized by the reversible addition-fragmentation chain transfer (RAFT) process. Second, upon simply changing the homopolymer's chain length or cosolvents during self-assembly, a wide range of new homopolymer-based nanostructures can be obtained, such as large compound micelles (LCMs), simple vesicles, large compound vesicles (LCVs), and hydrated large compound micelles (HLCMs) as a result of different intensity of inter/intra-polymer hydrogen bonding in the homopolymer self-assemblies. Moreover, micrometer-sized branched cylinders are formed by premixing PHPPA(36) and PHPPA(103), homopolymers, which is not observed by self-assembly of PHPPA(36) and PHPPA(103) individually. Third, we claim that the structures of homopolymer self-assemblies are much different from their block copolymer analogues due to homopolymer's fuzzy hydrophobic and hydrophilic domains compared to block copolymer's distinct ones. We confirm that the structure of micelle core or vesicle membrane (alike to each other in nature) consists of both hydrophilic and hydrophobic moieties, which is different from block copolymer micelles or vesicles with hydrophobic cores or membranes. Also, a dye encapsulation experiment is employed to identify and distinguish a new nanostructure, HLCMs, from LCMs. Our study has provided a new perspective on homopolymer self-assembly.