Thermodynamics of Model PαMSAN/dPMMA Blend: A Combined Study by SANS, Ellipsometry, and Locally Correlated Lattice (LCL) Theory
| Autor: | Yutaka Aoki, Jane E. G. Lipson, Ronald P. White, Joseph L. Keddie, Julia S. Higgins, João T. Cabral |
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| Rok vydání: | 2020 |
| Předmět: |
Materials science
Polymers and Plastics Polymers GLASS-TRANSITION TEMPERATURE Polymer Science Thermodynamics Neutron scattering FILMS SPINODAL DECOMPOSITION Miscibility 09 Engineering Thermal expansion Inorganic Chemistry DEPENDENCE Ellipsometry Tacticity Lattice (order) THICKNESS Materials Chemistry POLY(METHYL METHACRYLATE) CALIBRATION chemistry.chemical_classification Science & Technology Organic Chemistry POLYMER Polymer MOLECULAR-WEIGHT chemistry Physical Sciences Polymer blend THERMAL-EXPANSION 03 Chemical Sciences |
| Zdroj: | Macromolecules. 53:7084-7095 |
| ISSN: | 1520-5835 0024-9297 |
| DOI: | 10.1021/acs.macromol.0c00706 |
| Popis: | We combine experiment and theory to elucidate how small, local, structural changes can impact miscibility in polymer blends. Small-angle neutron scattering (SANS) experiments yield both the phase boundaries and the temperature dependence of the second derivative of the free energy of mixing. We demonstrate here, for the first time, that a fundamental characterization of pure component properties can be achieved through ellipsometry measurements on films of pure polymers (thickness ∼200 nm) to provide key data on the volume (or thickness)–temperature relationships; this development is significant given the scarcity of precise pressure–volume–temperature (PVT) data on pure polymers and blends. The experimental measurements allow us to undertake a detailed thermodynamic analysis of mixing using the locally correlated lattice (LCL) theory, which has been shown to be effective in rationalizing blend miscibility in terms of the pure component properties. We focus here on polymer blends of poly(α-methyl styrene-co-acrylonitrile) (PαMSAN) with deuterated poly(methyl methacrylate) (dPMMA), which differ in the degree of tacticity in the dPMMA component (atactic or syndiotactic), leading to an increase in miscibility for the latter. By combining LCL analysis of pure and mixed systems, we are able to connect tacticity changes to shifts in local nonbonded interactions, in free volume, and in thermal expansion coefficients, which in turn impact the thermodynamic compatibility of the blend components. |
| Databáze: | OpenAIRE |
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