Issue 2, 2022

The role of cooling rate in crystallization-driven block copolymer self-assembly

Abstract

Self-assembly of crystalline-coil block copolymers (BCPs) in selective solvents is often carried out by heating the mixture until the sample appears to dissolve and then allowing the solution to cool back to room temperature. In self-seeding experiments, some crystallites persist during sample annealing and nucleate the growth of core-crystalline micelles upon cooling. There is evidence in the literature that the nature of the self-assembled structures formed is independent of the annealing time at a particular temperature. There are, however, no systematic studies of how the rate of cooling affects self-assembly. We examine three systems based upon poly(ferrocenyldimethylsilane) BCPs that generated uniform micelles under typical conditions where cooling took pace on the 1–2 h time scale. For example, several of the systems generated elongated 1D micelles of uniform length under these slow cooling conditions. When subjected to rapid cooling (on the time scale of a few minutes or faster), branched structures were obtained. Variation of the cooling rate led to a variation in the size and degree of branching of some of the structures examined. These changes can be explained in terms of the high degree of supersaturation that occurs when unimer solutions at high temperature are suddenly cooled. Enhanced nucleation, seed aggregation, and selective growth of the species of lowest solubility contribute to branching. Cooling rate becomes another tool for manipulating crystallization-driven self-assembly and controlling micelle morphologies.

Graphical abstract: The role of cooling rate in crystallization-driven block copolymer self-assembly

Supplementary files

Article information

Article type
Edge Article
Submitted
27 Oct 2021
Accepted
29 Nov 2021
First published
02 Dec 2021
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2022,13, 396-409

The role of cooling rate in crystallization-driven block copolymer self-assembly

S. Song, J. Jiang, E. Nikbin, J. Y. Howe, I. Manners and M. A. Winnik, Chem. Sci., 2022, 13, 396 DOI: 10.1039/D1SC05937H

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