Liquid-liquid equilibria and theta temperatures in binary solvent-copolymer solutions from a perturbed hard-sphere-chain equation of state
✍ Scribed by Toshiaki Hino; Yuhua Song; John M. Prausnitz
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 803 KB
- Volume
- 34
- Category
- Article
- ISSN
- 0887-6266
No coin nor oath required. For personal study only.
✦ Synopsis
The perturbed hard-sphere-chain (PHSC) equation of state for copolymer systems is used to calculate liquid-liquid equilibria for binary solvent/copolymer systems that exhibit simultaneously an upper critical solution temperature (UCST) and a lower critical solution temperature. The PHSC equation of state for copolymer solutions uses those binary parameters that represent liquid-liquid equilibria for the two parent homopolymer solutions. An additional intersegmental parameter is also required to define the interaction energy between a pair of chemically dissimilar segments comprising the copolymer molecule. Theory is compared with experiment for binary copolymer solutions containing poly(styrene-coa-methylstyrene) random copolymers. Using the same K ~~, the intersegmental parameter between styrene and a-methylstyrene segments, theory and experiment show fair agreement for the copolymer-composition dependence of theta temperatures associated with UCST in cyclohexane, methyl cyclohexane, and decalin. A comparison is also made between K~~ obtained from the copolymer-solution data and that obtained from the coexistence curve of homopolymer blends containing polystyrene and poly(a-methylstyrene). Data for copolymer solutions require a K~~ that represents interactions more unfavorable than those in homopolymer blends.