Song Shaofei, Liu Xuemin, Nikbin Ehsan, Howe Jane Y, Yu Qing, Manners Ian, Winnik Mitchell A
Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6, Canada.
School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, P. R. China.
J Am Chem Soc. 2021 Apr 28;143(16):6266-6280. doi: 10.1021/jacs.1c02395. Epub 2021 Apr 15.
Fiber-like (1D) core-crystalline micelles of uniform length can be obtained in protocols involving multiple steps from block copolymers (BCPs) in which crystallization of the core-forming polymer drives the self-assembly. Here we report a systematic study that shows that adding small amounts (<5 w/w%) of a homopolymer corresponding to the core-forming block of the BCP enables uniform 1D micelles (mean lengths = 0.6 to 9.7 μm) to be obtained in a single step, simply by heating the mixture in a selective solvent followed by slow cooling. A series of poly(ferrocenyldimethylsilane) (PFS) BCPs with different corona-forming blocks and different compositions as well as PFS homopolymers of different lengths were examined. Dye labeling and confocal fluorescence microscopy showed that the homopolymer ends up in the center of the micelle, signaling that it served as the initial seed for epitaxial micelle growth. The rate of unimer addition was strongly enhanced by the length of the PFS block, and this enabled more complex structures to be formed in one-pot self-assembly experiments from mixtures of two or three BCPs with different PFS block lengths. Furthermore, BCP mixtures that included PFS--PI (PI = polyisoprene) and PFS--PDMS with similar PFS block lengths resulted in simultaneous addition to growing micelles, resulting in a patchy block that could be visualized by staining the vinyl groups of the PI with Pt nanoparticles. This approach also enabled scale up, so that uniform 1D micelles of controlled architecture can be obtained at concentrations of 10 w/w % solids or more.
通过涉及多步的方案，从嵌段共聚物（BCP）中可以获得长度均匀的纤维状（一维）核晶态胶束，其中形成核的聚合物的结晶驱动自组装。在此，我们报告一项系统研究，该研究表明，添加少量（<5 w/w%）与BCP的核形成嵌段相对应的均聚物，只需在选择性溶剂中加热混合物然后缓慢冷却，就能在一步中获得均匀的一维胶束（平均长度 = 0.6至9.7μm）。研究了一系列具有不同冠层形成嵌段和不同组成的聚（二茂铁二甲基硅烷）（PFS）BCP以及不同长度的PFS均聚物。染料标记和共聚焦荧光显微镜显示，均聚物最终位于胶束中心，这表明它作为外延胶束生长的初始种子。单聚物添加速率因PFS嵌段的长度而显著提高，这使得在一锅自组装实验中，由两种或三种具有不同PFS嵌段长度的BCP混合物能够形成更复杂的结构。此外，包含具有相似PFS嵌段长度的PFS - PI（PI = 聚异戊二烯）和PFS - PDMS的BCP混合物会同时添加到正在生长的胶束中，形成一个斑驳的嵌段，可用铂纳米颗粒对PI的乙烯基进行染色来可视化。这种方法还能够扩大规模，从而可以在10 w/w%或更高的固体浓度下获得具有可控结构的均匀一维胶束。
