Determination of reaction kinetics by time-resolved small-angle X-ray scattering during polymerization-induced self-assembly: direct evidence for monomer-swollen nanoparticles

DOI: 10.1002/anie.202312119

Authors: Guoxing Liao (South China University of Technology, South China Advanced Institute for Soft Matter Science and Technology) , Matthew J. Derry (Aston University) , Andrew J. Smith (Diamond Light Source) , Steven P. Armes (The University of Sheffield) , Oleksandr Mykhaylyk (The University of Sheffield)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie International Edition

State: Published (Approved)
Published: November 2023
Diamond Proposal Number(s): 14892 , 15525 , 24680

Abstract: The kinetics of heterogeneous polymerization is determined directly using small-angle X-ray scattering (SAXS). This important advance 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. The 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 should be applicable to other heterogeneous polymerization formulations.

Journal Keywords: polymerization kinetics; polymerization-induced self- assembly; time-resolved small-angle X-ray scattering; block copolymer nanoparticles; RAFT dispersion polymerization

Subject Areas: Materials, Chemistry


Instruments: I22-Small angle scattering & Diffraction

Added On: 27/11/2023 08:45

Documents:
Angew Chem Int Ed - 2023 - Liao - Determination of Reaction Kinetics by Time%E2%80%90Resolved Small%E2%80%90angle X%E2%80%90ray Scattering during.pdf

Discipline Tags:

Physical Chemistry Chemistry Materials Science Nanoscience/Nanotechnology Polymer Science

Technical Tags:

Scattering Small Angle X-ray Scattering (SAXS)