Thermodynamics of Highly Interacting Blend PCHMA/dPS by TOF-SANS

Sharratt, WN ORCID: 0000-0003-2148-8423, Aoki, Y, Pont, S ORCID: 0000-0002-0087-9989, Seddon, D, Dewhurst, C, Porcar, L, Clarke, N and Cabral, JT ORCID: 0000-0002-2590-225X (2023) Thermodynamics of Highly Interacting Blend PCHMA/dPS by TOF-SANS Macromolecules, 56 (14). pp. 5619-5627. ISSN 0024-9297, 1520-5835

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Abstract

We investigate the thermodynamics of a highly interacting blend of poly(cyclohexyl methacrylate)/deuterated poly(styrene) (PCHMA/dPS) with small-angle neutron scattering (SANS). This system is experimentally challenging due to the proximity of the blend phase boundary (>200 °C) and degradation temperatures. To achieve the large wavenumber q-range and flux required for kinetic experiments, we employ a SANS diffractometer in time-of-flight (TOF) mode at a reactor source and ancillary microscopy, calorimetry, and thermal gravimetric analysis. Isothermal SANS data are well described by random-phase approximation (RPA), yielding the second derivative of the free energy of mixing (G″), the effective interaction (χ̅) parameter, and extrapolated spinodal temperatures. Instead of the Cahn-Hilliard-Cook (CHC) framework, temperature (T)-jump experiments within the one-phase region are found to be well described by the RPA at all temperatures away from the glass transition temperature, providing effectively near-equilibrium results. We employ CHC theory to estimate the blend mobility and G″(T) conditions where such an approximation holds. TOF-SANS is then used to precisely resolve G″(T) and χ̅(T) during T-jumps in intervals of a few seconds and overall timescales of a few minutes. PCHMA/dPS emerges as a highly interacting partially miscible blend, with a steep dependence of G″(T) [mol/cm³] = −0.00228 + 1.1821/T [K], which we benchmark against previously reported highly interacting lower critical solution temperature (LCST) polymer blends.

Item Type:	Article
Uncontrolled Keywords:	40 Engineering, 34 Chemical Sciences
Divisions:	Faculty of Science & Engineering > School of Engineering
Depositing User:	Symplectic Admin
Date Deposited:	25 Jul 2023 11:24
Last Modified:	01 Mar 2026 03:57
DOI:	10.1021/acs.macromol.3c00511
Open Access URL:	https://pubs.acs.org/doi/10.1021/acs.macromol.3c00...
Related Websites:	Author Publisher
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3171886
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