Phase Separation Curves of Poly(α-methylstyrene) in Methylcyclohexane

Abstract

We report new measurements of the liquid−liquid phase separation curves of poly(α-methylstyrene) + methylcyclohexane, for three well-characterized samples of the polymer with number average molecular weights of (A) 19 700, (B) 32 300, and (C) 72 000 g/mol. Sample A (polydispersity index PI = 1.02) has a critical point at a mass fraction m c of polymer of 0.20 ± 0.02 and a critical temperature T c at (305.70 ± 0.09) K. The critical point for sample A is not at the apex of the phase separation curve, which indicates that the polymer was not sufficiently monodisperse to behave as one component. Sample B (PI = 1.02) has m c = 0.15 ± 0.02 and T c = (318.3 ± 0.4) K; this critical point is at the apex of the phase separation curve within our resolution. Sample C (PI = 1.05) has m c = 0.11 ± 0.02 (not the apex of the curve) and T c = (328.9 ± 0.4) K. From these measurements, we find a theta temperature ϑ of (357 ± 5) K and an entropy of dilution parameter ψ1 of 0.49 ± 0.06. The polymer/solvent interaction parameter χ1 at T c for each sample is (A) 0.54 ± 0.01, (B) 0.56 ± 0.01, and (C) 0.58 ± 0.01. The uncertainties for ϑ, ψ1, and χ1 are given as one standard deviation.

Prediction of the θ(UCST) of Polymer Solutions: A Quantitative Structure−Property Relationship Study

“…Consequently, a set of 107 experimental θ(UCST) data was found in this reference and used in this study. These experimental data have been collected from other original literature. − This dataset includes 23 polymers and 92 solvents, which is presented in Table .…”

Cloud Curves of Polystyrene or Poly(methyl methacrylate) or Poly(styrene-co-methyl methacrylate) in Cyclohexanol Determined with a Thermo-Optical Apparatus

“…Examples include polyethylene (PE) + ethylene, 5 polyisobutylene (PIB) + diisobutyl ketone, 6 and poly-R-methylstyrene + methyl cyclohexane. 7 On the other hand, lower critical solution temperature (LCST) behavior is observed for a number of common systems such as PE 8 and PIB 9 in various n-alkane solvents as well as in polystyrene (PS) + benzene and PS + methyl elthyl ketone. 10 Both UCST and LCST behavior have been found for PS + cyclohexane.…”

“…The most commonly observed T − w diagram for polymer solutions exhibits a single binodal curve with an upper critical solution temperature (UCST) below which the system separates into two co-exisitng phases. Examples include polyethylene (PE) + ethylene, polyisobutylene (PIB) + diisobutyl ketone, and poly-α-methylstyrene + methyl cyclohexane . On the other hand, lower critical solution temperature (LCST) behavior is observed for a number of common systems such as PE and PIB in various n -alkane solvents as well as in polystyrene (PS) + benzene and PS + methyl elthyl ketone .…”

“…The method is manual, slow, and somewhat subjective but nevertheless reliable. The cloud curves of poly(α-methyl styrene) + methyl cyclohexane were measured in this way by Pruessner et al, while Saeki et al , measured cloud curves for solutions of PS in a number of different solvents at mass fractions of polymer of up to 0.25.…”