Morphological Stabilization of Block Copolymer Worms Using Asymmetric Cross-Linkers during Polymerization-Induced Self-Assembly

Abstract

Block copolymer worm stabilization via cross-linking during polymerization-induced self-assembly (PISA) is challenging. This is because block copolymer worms typically occupy a narrow regime in the phase diagram, and in situ cross-linking may hinder a morphological transition from sphere to worm. In this work, in situ cross-linking of block copolymer worms during PISA was studied using three different asymmetric cross-linkers, each bearing a pair of double bonds with different reactivities. Specifically, ethanolic PISA syntheses targeting poly­(2-(dimethyl­amino)­ethyl methacrylate)-b-poly­(benzyl methacrylate) diblock copolymer worms were investigated in the presence of vinyl methacrylate, allyl methacrylate, or 4-allyloxybenzyl methacrylate. The copolymerizations of benzyl methacrylate with the asymmetric cross-linkers underwent progressive branching to finally cross-linking of the block copolymer worms. While all the three asymmetric cross-linkers were able to cross-link worms, 4-allyloxybenzyl methacrylate with a structure mimicking benzyl methacrylate showed the best results with minimal perturbation to the worm morphology.

New Insights into RAFT Dispersion Polymerization‐Induced Self‐Assembly: From Monomer Library, Morphological Control, and Stability to Driving Forces

“…Postpolymerization cross‐linking is a reliable approach to stabilize morphology because it does not disturb the PISA process and there are many well‐known efficient organic reactions to do so . For example, acid units were introduced into the stabilizer block and then reacted with diamine to result in shell cross‐linked nano‐objects .…”

“…c) Synthesis of in situ cross‐linked PBnMA‐based worms with three asymmetric cross‐linkers. Reproduced with permission . Copyright 2018, American Chemical Society.…”

“…However, further polymerization exceeding the IEP resulted in electrostatic repulsion caused by the excess charge of the PAEAM block, which split the networks into spheres and further into fragments. Later, various intriguing low-dimensional PICs including nanofilms and nanowires were successfully synthesized via quantitative PIESA employing a shorter stabilizer PHPMAM 65 block at an equal molar ratio of the oppositely charged units (Figure 8a). [17a] A medium-dependent shape selectivity of the PICs was also demonstrated; compartmentalized vesicles and large-area nanofilms were obtained in water while nanowires and porous nanofilms were formed in methanol/water mixture.…”

Copolymerization Kinetics of a Simple Methacrylate and Functional Comonomers Via Cu(0)‐mediated Reversible Deactivation Radical Polymerization

“…Copolymer for crosslinking, industrially significant approach to form stable material, provides other examples. Allyl methacrylate (AMA) and glycidyl methacrylate (GMA) have been widely and extensively employed as a comonomer in a variety of industrial applications for effective crosslinking . A coating agent to form functional surfaces with long‐term stability is an excellent example: surface energy can be effectively controlled with crosslinking of GMA incorporated copolymers .…”

Ketone‐Functionalized Polymer Nano‐Objects Prepared via Photoinitiated Polymerization‐Induced Self‐Assembly (Photo‐PISA) Using a Poly(diacetone acrylamide)‐Based Macro‐RAFT Agent

“…Cross-linked worms and vesicles have been synthesized by this one-pot method without further postpolymerization reactions. [72,73] Although cross-linking of PISA nano-objects has been explored, however, most formulations were focused on the preparation of core-cross-linked polymer nano-objects. As an alternative, shell-cross-linking is another important strategy to prepare cross-linked polymer nano-objects.…”