Tuning the Properties of Hydrogen-bonded Block Copolymer Worm Gels Prepared via Polymerization-Induced Self-Assembly

Abstract

Polymerization-induced self-assembly (PISA) is exploited to design hydrogen-bonded poly(stearyl methacrylate)-poly(benzyl methacrylate) [PSMA-PBzMA] worm gels in n-dodecane. Using a carboxylic acid-based RAFT agent facilitates hydrogen bonding between neighboring worms to produce much stronger physical gels than those prepared using the analogous methyl ester-based RAFT agent. Moreover, tuning the proportion of these two types of end-groups on the PSMA chains enables the storage modulus (G’) of the 20% w/w worm gel to be tuned from ~4.5 kPa up to ~114 kPa. This is achieved via two complementary routes: (i) an in situ approach using binary mixtures of acid- and ester-capped PSMA stabilizer chains during PISA or (ii) a post-polymerization processing strategy using a thermally-induced worm-to-sphere transition to mix acid- and ester-functionalized spheres at 110 °C that fuse to form worms on cooling to 20°C. SAXS and rheology studies of these hydrogen-bonded worm gels provide detailed insights into their inter-worm interactions and physical behavior, respectively. In the case of the carboxylic acid-functionalized worms, SAXS provides direct evidence for additional inter-worm interactions, while rheological studies confirm both a significant reduction in critical gelation concentration (from approximately 10% w/w to 2-3% w/w) and a substantial increase in critical gelation temperature (from 41 °C to 92 °C). It is remarkable that a rather subtle change in the chemical structure results in such improvements in gel strength, gelation efficiency and gel cohesion.

Publication DOI: https://doi.org/10.1039/D1SC03156B
Divisions: College of Engineering & Physical Sciences > Aston Institute of Materials Research (AIMR)
College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
College of Engineering & Physical Sciences
Additional Information: © The Royal Society of Chemistry 2021. This article is Open Access under a CC BY license. Funding: S.P.A. acknowledges an EPSRC Established Career Fellowship (EP/R003009/1). The Leverhulme Trust is also thanked for postdoctoral funding of M.J.D. (RPG-2016-330).
Uncontrolled Keywords: Chemistry(all)
Full Text Link:
Related URLs: https://pubs.rs ... 1/SC/D1SC03156B (Publisher URL)
http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2021-09-28
Published Online Date: 2021-08-05
Accepted Date: 2021-08-04
Authors: Raphael, Eleanor
Derry, Matthew (ORCID Profile 0000-0001-5010-6725)
Hippler, Michael
Armes, Steven P.

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