Transparent diblock copolymer nanoparticle dispersions via efficient RAFT emulsion polymerisation in ionic liquid

Anisha Patel; Georgia L. Maitland; Evelina Liarou; Paul D. Topham; Matthew J. Derry

doi:10.1039/d5py00076a

Transparent diblock copolymer nanoparticle dispersions via efficient RAFT emulsion polymerisation in ionic liquid

Anisha Patel, Georgia L. Maitland, Evelina Liarou, Paul D. Topham, Matthew J. Derry^*

^*Corresponding author for this work

Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK

Research output: Contribution to journal › Article › peer-review

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Abstract

We report the first reversible addition–fragmentation chain transfer polymerisation-induced self-assembly (RAFT-PISA) in ionic liquid (IL) that proceeds under emulsion conditions. Moreover, this formulation exploits refractive index contrast matching to generate highly transparent nanoparticle dispersions. Specifically, 1-ethyl-3-methyl-imidazolium ethylsulfate, [EMIM][EtOSO3], was used as the solvent for the chain extension of poly(2-hydroxyethyl methacrylate) (PHEMA) macromolecular chain transfer agents (macro-CTAs) using n-butyl methacrylate (BuMA) via RAFT emulsion polymerisation. Two series of PHEMAx-b-PBuMAy diblock copolymers with target PBuMA degrees of polymerisation (DPs) varying from 50 to 1000 were synthesised using either a PHEMA21 or PHEMA77 macro-CTA. All resulting nanoparticle dispersions yielded highly transparent dispersions, even when nanoparticle diameters exceeded 100 nm, due to the closely matched refractive index values of the [EMIM][EtOSO3] solvent and PBuMA nanoparticle core. Detailed analysis using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) confirmed the presence of spherical nanoparticles. Furthermore, the synthesis of PHEMA-b-PBuMA via this new PISA formulation was directly compared to equivalent block copolymer syntheses conducted in N, N-dimethylformamide (DMF) or ethanol/water mixtures. It was found that syntheses conducted in [EMIM][EtOSO3] resulted in the highest monomer conversions (up to >99%) and lowest dispersity (ĐM) values (as low as 1.16) in the shortest reaction times (2 hours) compared to the other solvent systems. This work demonstrates the use of ILs as a more sustainable and effective solvent for RAFT–PISA via the development of the first emulsion PISA formulation in IL.

Original language	English
Pages (from-to)	2767-2777
Number of pages	11
Journal	Polymer Chemistry
Volume	16
Issue number	23
Early online date	14 May 2025
DOIs	https://doi.org/10.1039/d5py00076a
Publication status	Published - 21 Jun 2025

Bibliographical note

Data Access Statement

Additional data to support this article, including polymer and nanoparticle characterisation data, UV-vis measurements, small-angle X-ray scattering data and models and transmission electron microscopy images, have been included as part of the ESI.

Funding

M. J. D. wishes to thank EPSRC for funding (grant number EP/Y005309/1) and for providing a DTP studentship for A. P. (EPSRC DTP 2020\u20132021, Aston University, Grant Ref: EP/T518128/1). The Aston Institute for Membrane Excellence (AIME) is funded by UKRI's Research England as part of their Expanding Excellence in England (E3) fund. E. L. thanks the Leverhulme Trust for an Early Career Fellowship (ECF-2023-602) and the Electron Microscopy RTP (University of Warwick) for access to the microscopes. Small-angle X-ray scattering (SAXS) experiments were conducted remotely with the support of Diamond Light Source, instrument B21 (experiment sm39167), and we would like to specifically acknowledge the support received by Dr Nathan Cowieson, Katsuaki Inoue, and Jodie Lavender during our experiment.

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10.1039/d5py00076aLicence: CC BY 3.0

Transparent diblock copolymer nanoparticle dispersions via efficient RAFT emulsion polymerisation in ionic liquid
Copyright © The Royal Society of Chemistry 2025. Open Access Article. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
Final published version, 3.12 MBLicence: CC BY 3.0

Cite this

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title = "Transparent diblock copolymer nanoparticle dispersions via efficient RAFT emulsion polymerisation in ionic liquid",

abstract = "We report the first reversible addition–fragmentation chain transfer polymerisation-induced self-assembly (RAFT-PISA) in ionic liquid (IL) that proceeds under emulsion conditions. Moreover, this formulation exploits refractive index contrast matching to generate highly transparent nanoparticle dispersions. Specifically, 1-ethyl-3-methyl-imidazolium ethylsulfate, [EMIM][EtOSO3], was used as the solvent for the chain extension of poly(2-hydroxyethyl methacrylate) (PHEMA) macromolecular chain transfer agents (macro-CTAs) using n-butyl methacrylate (BuMA) via RAFT emulsion polymerisation. Two series of PHEMAx-b-PBuMAy diblock copolymers with target PBuMA degrees of polymerisation (DPs) varying from 50 to 1000 were synthesised using either a PHEMA21 or PHEMA77 macro-CTA. All resulting nanoparticle dispersions yielded highly transparent dispersions, even when nanoparticle diameters exceeded 100 nm, due to the closely matched refractive index values of the [EMIM][EtOSO3] solvent and PBuMA nanoparticle core. Detailed analysis using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) confirmed the presence of spherical nanoparticles. Furthermore, the synthesis of PHEMA-b-PBuMA via this new PISA formulation was directly compared to equivalent block copolymer syntheses conducted in N, N-dimethylformamide (DMF) or ethanol/water mixtures. It was found that syntheses conducted in [EMIM][EtOSO3] resulted in the highest monomer conversions (up to >99%) and lowest dispersity ({\D}M) values (as low as 1.16) in the shortest reaction times (2 hours) compared to the other solvent systems. This work demonstrates the use of ILs as a more sustainable and effective solvent for RAFT–PISA via the development of the first emulsion PISA formulation in IL.",

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AU - Patel, Anisha

AU - Maitland, Georgia L.

AU - Liarou, Evelina

AU - Topham, Paul D.

AU - Derry, Matthew J.

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AB - We report the first reversible addition–fragmentation chain transfer polymerisation-induced self-assembly (RAFT-PISA) in ionic liquid (IL) that proceeds under emulsion conditions. Moreover, this formulation exploits refractive index contrast matching to generate highly transparent nanoparticle dispersions. Specifically, 1-ethyl-3-methyl-imidazolium ethylsulfate, [EMIM][EtOSO3], was used as the solvent for the chain extension of poly(2-hydroxyethyl methacrylate) (PHEMA) macromolecular chain transfer agents (macro-CTAs) using n-butyl methacrylate (BuMA) via RAFT emulsion polymerisation. Two series of PHEMAx-b-PBuMAy diblock copolymers with target PBuMA degrees of polymerisation (DPs) varying from 50 to 1000 were synthesised using either a PHEMA21 or PHEMA77 macro-CTA. All resulting nanoparticle dispersions yielded highly transparent dispersions, even when nanoparticle diameters exceeded 100 nm, due to the closely matched refractive index values of the [EMIM][EtOSO3] solvent and PBuMA nanoparticle core. Detailed analysis using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) confirmed the presence of spherical nanoparticles. Furthermore, the synthesis of PHEMA-b-PBuMA via this new PISA formulation was directly compared to equivalent block copolymer syntheses conducted in N, N-dimethylformamide (DMF) or ethanol/water mixtures. It was found that syntheses conducted in [EMIM][EtOSO3] resulted in the highest monomer conversions (up to >99%) and lowest dispersity (ĐM) values (as low as 1.16) in the shortest reaction times (2 hours) compared to the other solvent systems. This work demonstrates the use of ILs as a more sustainable and effective solvent for RAFT–PISA via the development of the first emulsion PISA formulation in IL.

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DO - 10.1039/d5py00076a

M3 - Article

SN - 1759-9954

VL - 16

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JO - Polymer Chemistry

JF - Polymer Chemistry

IS - 23

ER -

Transparent diblock copolymer nanoparticle dispersions via efficient RAFT emulsion polymerisation in ionic liquid

Abstract

Bibliographical note

Data Access Statement

Funding

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