Pressure dependence of the miscibility of poly(vinyl methyl ether) and polystyrene: Theoretical representation

Abstract

The present calculations were performed on the basis of the Sanchez-Lacombe-Balasz lattice fluid theory. The two system specific parameters ε12* and δε* required for that purpose have been obtained from the spinodal temperatures measured (SANS) for mixtures of poly(vinyl methyl ether) (PVME) and deuterated polystyrenes (d-PS) by Schwahn and coworkers. The experimental data reported for atmospheric pressure and six representatives of the present system are well described theoretically, where ε12* does not depend on molar mass and δε* decreases only slightly as the chain length of d-PS is raised. The measured pressure influences on the spinodal conditions correspond to an approximately linear reduction of δε* with increasing P; this observation should reflect the volume changes associated with the formation of specific interactions. According to the present calculations the critical composition shifts markedly towards pure PVME as P is raised. Since experimental data are commonly expressed in terms of the Flory-Huggins theory, the current results were also translated into Flory-Huggins interaction parameters and evaluated with respect to the contributions of enthalpy and of entropy. The agreement between experimental information and that calculated from the Sanchez-Lacombe-Balasz lattice fluid theory is reasonable.

Effects of Pressure and Molecular Weight on the Miscibility of Polystyrene and Cyclohexane

“…According to our previous calculations, [64,65] the total interaction energy per mer should be linearly dependent on pressure besides being a function of temperature, i. e.,…”

“…[64, 65, 67 -89] Although FOV theory and SLLFT are successful in calculating the phase diagrams of polymer solutions and polymer mixtures near or at atmosphere pressure for some systems containing polymers, [8, 12, 16, 63 -66] it often failed to use them to predict the pressure dependence of equilibrium phase separation behavior at high pressures without modification of the theories. An et al [64,65] suggested a method to calculate the effects of pressure on the miscibility of polymer solutions and polymer mixtures by considering the interaction energy parameter as a linear function of pressure and obtained the phase diagrams in accordance with experimental data at high pressures. However, it is difficult to conduct further research on this subject due to the scarcity of experimental information on phase diagrams at different elevated pressures.…”

Polymer‐Polymer Interaction: Consistent Modeling in Terms of Chain Connectivity and Conformational Response

“…In this context it is interesting to note that this diminution persists for PVME/d-PS down to room temperature [17] according to an evaluation of neutron scattering experiments. [18] The most pronounced temperature influences are obtained from spinodal temperatures [19][20][21] measured for the system PVME/d-PS and evaluated [22] according to the Sanchez-Lacombe-Balasz theory. The least temperature influences follow from the evaluation of cloud point data [23] for the system PVME/PS by means of the Sanchez-Lacombe theory.…”

“…Full lines: evaluation of SANS data [19][20][21] for the system PVME/d-PS according to the Sanchez-Lacombe-Balasz theory. [22] Broken lines: obtained from SANS measurement for the system PVME/ d-PS and read from Figure 8 of ref. [19] Dotted lines: calculated [24] from published cloud point curves [23] for the system PVME/PS by means of the Sanchez-Lacombe theory.…”

Abnormal pressure dependence of the phase boundaries in TL/PEO/P(EO-b-DMS) ternary mixtures

“…In contrast to FH theory, as shown above, the experimental results proved that pressure can play an important role in the phase separation of polymer-containing systems. [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] In our group, there has been much research done on pressure effects on the behavior of polymers in both experiment and theory. [12][13][14][23][24][25][26][27] In this paper, we examined the behavior of ternary polymer mixtures containing a diblock copolymer with homopolymer and toluene as a function of mixture composition and temperature to obtain an experimental phase diagram for a solvent/copolymer/homopolymer mixture.…”