Determination of Reaction Kinetics by Time-Resolved Small-angle X-ray Scattering during Polymerization-Induced Self-Assembly: Direct Evidence for Monomer-Swollen Nanoparticles

Abstract

The kinetics of heterogeneous polymerization is determined directly using small-angle X-ray scattering (SAXS). This important advancement is exemplified for the synthesis of sterically-stabilized diblock copolymer nanoparticles by reversible addition-fragmentation chain transfer (RAFT) dispersion polymerization of benzyl methacrylate (BzMA) in mineral oil at 90 °C. The principle of mass balance is invoked to derive a series of equations for the analysis of the resulting time-resolved SAXS patterns. Importantly, there is a continuous change in the X-ray scattering length density for the various components within the reaction mixture. This enables the volume fraction of unreacted BzMA monomer to be calculated at any given time point, which enables the polymerization kinetics to be monitored in situ directly without relying on supplementary characterization techniques. Moreover, SAXS enables the local concentration of both monomer and solvent within the growing swollen nanoparticles to be determined during the polymerization. Data analysis reveals that the instantaneous rate of BzMA polymerization is proportional to the local monomer concentration within the nanoparticles. In principle, this powerful new time-resolved SAXS approach can be applicable to other heterogeneous polymerization formulations.

Publication DOI: https://doi.org/10.1002/anie.202312119
Divisions: College of Engineering & Physical Sciences > School of Infrastructure and Sustainable Engineering > Chemical Engineering & Applied Chemistry
College of Engineering & Physical Sciences
College of Engineering & Physical Sciences > Aston Institute of Materials Research (AIMR)
College of Engineering & Physical Sciences > Aston Polymer Research Group
College of Engineering & Physical Sciences > Aston Advanced Materials
Funding Information: We are grateful to Diamond Light Source for providing synchrotron beam time (SM14892, SM15525 and SM24680) and thank the personnel of I22 for their assistance. S.P.A. and O.O.M. thank the Leverhulme Trust for post‐doctoral funding of M.J.D. (RPG‐2016‐330)
Additional Information: Copyright © 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Uncontrolled Keywords: Block Copolymer Nanoparticles,Polymerization Kinetics,Polymerization-Induced Self-Assembly,RAFT Dispersion Polymerization,Time-Resolved Small-Angle X-Ray Scattering,General Chemistry,Catalysis
Publication ISSN: 1521-3773
Last Modified: 07 Oct 2024 07:54
Date Deposited: 27 Nov 2023 15:16
Full Text Link:
Related URLs: https://onlinel ... /anie.202312119 (Publisher URL)
http://www.scop ... tnerID=8YFLogxK (Scopus URL)
PURE Output Type: Article
Published Date: 2024-01-08
Published Online Date: 2023-11-23
Accepted Date: 2023-11-23
Authors: Liao, Guoxing
Derry, Matthew J. (ORCID Profile 0000-0001-5010-6725)
Smith, Andrew J.
Armes, Steven P.
Mykhaylyk, Oleksandr O.

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