Estimation of interaction energies by the critical molecular weight method: 1. Blends with polycarbonates

Abstract

SYNOPSISThe interaction energies between PS, Pa-MS, and PMMA with several bisphenol-A-based polycarbonates were quantitatively determined from oligomer/oligomer, oligomer/ homopolymer, and homopolymer/copolymer blends. Interaction energies were calculated from the Flory-Huggins theory and the Sanchez-Lacombe equation of state theory using experimental cloud points or miscibility boundaries. Alkyl addition to the phenyl rings of polycarbonate is favorable for miscibility with polystyrene whereas halogenation of the bisphenol connector unit is favorable for miscibility with poly ( methyl methacrylate). Interaction energies are quantitatively ranked and described qualitatively in terms of changes in the electronic charge distribution of the polymer repeat units as calculated by SYBYL software.

Control of phase separation behavior of PC/PMMA blends and their application to the gas separation membranes

“…The blend for commercial molecular weights of both components is immiscible at equilibrium due to an LCST-type phase boundary that lies below the glass transition temperature of the blend. 35 Callaghan et al 37 prepared various PC/PMMA blends by changing molecular weights of both components and then examined their glass transition temperatures and phase behavior. Miscible blends were found for the blend of PC and PMMA at which the molecular weight of either component was lower than certain value.…”

“…[31][32][33][34][35][36][37] It has been concluded that the blend is either miscible or immiscible, depending upon the molecular weights of components that were blended. The blend for commercial molecular weights of both components is immiscible at equilibrium due to an LCST-type phase boundary that lies below the glass transition temperature of the blend.…”

“…Because the melting temperature of PC crystals varied from 220 to 290°C, any reliable observation of phase behavior precluded due to the thermal instability of PMMA at these high temperatures. 37 In this study, the various blends of PC and PMMA were prepared by changing molecular weights of PMMA to avoid solvent-induced PC crystals. The immiscible blends of PC/PMMA (60 K) and PC/PMMA (100K) showed overlapped two T g s between the pure component T g s. These blends were slightly cloudy, but PC melting peak was not observed in the DSC thermograms.…”

“…[35][36][37] Interaction energy densities of PC and PMMA that were obtained by a reverse method using phase boundaries due to LCST and an equation of state are the most reliable to date. 37 In a previous research, however, any reliable phase boundaries were precluded due to the presence of solvent-induced PC crystals and the thermal instability of PMMA. To prepare miscible blends without solvent-induced PC crystals, the molecular weights of each component were carefully controlled in this study.…”

“…[31][32][33][34][35][36][37] Through numerous studies, it has been proven that PC/PMMA blends appeared to be right on the edge of miscibility. [35][36][37] Interaction energy densities of PC and PMMA that were obtained by a reverse method using phase boundaries due to LCST and an equation of state are the most reliable to date. 37 In a previous research, however, any reliable phase boundaries were precluded due to the presence of solvent-induced PC crystals and the thermal instability of PMMA.…”