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 a 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.

Graphical abstract: Tuning the properties of hydrogen-bonded block copolymer worm gels prepared via polymerization-induced self-assembly

Supplementary files

Article information

Article type
Edge Article
Submitted
10 Jun 2021
Accepted
04 Aug 2021
First published
05 Aug 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 license

Chem. Sci., 2021, Advance Article

Tuning the properties of hydrogen-bonded block copolymer worm gels prepared via polymerization-induced self-assembly

E. Raphael, M. J. Derry, M. Hippler and S. P. Armes, Chem. Sci., 2021, Advance Article , DOI: 10.1039/D1SC03156B

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