Shear-Induced Alignment of Block Copolymer Worms in Mineral Oil

Abstract

Poly(stearyl methacrylate)-poly(benzyl methacrylate) [PSMA-PBzMA] diblock copolymer worms were synthesized directly in mineral oil via reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization at 90 °C. Free-standing gels were obtained from this polymerization-induced self-assembly (PISA) formulation when targeting PSMA13-PBzMA65 dispersions at 5% w/w to 20% w/w copolymer concentration. Gel permeation chromatography (GPC) studies indicated that almost identical copolymer chains were obtained in all cases, while transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS) studies confirmed that highly anisotropic worms were formed with mean cross-sectional diameters of 11.9-13.1 nm. These worms undergo a thermoreversible worm-to-sphere transition on heating up to 150 °C. Rheological studies were conducted to characterize the shear rate- and concentration-dependent behaviour caused by this change in copolymer morphology, where the initial shear-thinning worm gels form spheres (i.e. a Newtonian fluid) on heating up to 150 °C. Complementary shear-induced polarized light imaging (SIPLI) experiments confirmed the formation of aligned linear worms under applied shear between 80 °C and 110 °C, with high-viscosity dispersions of branched worms being obtained at 20-60 °C and low-viscosity spheres being produced at 150 °C. This study informs the use of such block copolymer worms as rheology modifiers for non-polar oils, which is of potential interest for the automotive industry.

Publication DOI: https://doi.org/10.1039/D1SM01011E
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: This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. Funding: The Lubrizol Corporation is thanked for funding a PhD studentship for M.J.D. and for permission to publish this work. The Leverhulme Trust is also thanked for post-doctoral funding of M.J.D. (RPG-2016-330). S.P.A. acknowledges an EPSRC Established Career Fellowship (EP/R003009/1).
Full Text Link:
Related URLs: https://pubs.rs ... 1/SM/D1SM01011E (Publisher URL)
PURE Output Type: Article
Published Date: 2021-09-15
Published Online Date: 2021-09-15
Accepted Date: 2021-09-14
Authors: Derry, Matthew (ORCID Profile 0000-0001-5010-6725)
Mykhaylyk, Oleksandr O.
Armes, Steven P.

Download

[img]

Version: Accepted Version

License: Creative Commons Attribution

| Preview

Export / Share Citation


Statistics

Additional statistics for this record