Ionic Complexation as a Method of Miscibility Enhancement of Polystyrene/ Polypropylene Oxide Blends
The blending of different polymers often results in phase separation due to low entropy of mixing and unfavorable enthalpy of mixing. Methods to increase polymer miscibility would allow for mixing of properties of two different materials in one blend. One method of making a miscible polymer blend is by using polymers with complementary functional groups to drive mixing. In this research, sulfonic acid functionalized polystyrene (SPS) and amine-terminated poly(propylene oxide) were used to make such a polymer blend. The percentage of sulfonation and functionality of the PPO were varied and samples were tested for clarity and mechanical properties. Polystyrene sulfonation levels were 2.5, 3.7, and 6.5%. Di-functional, secondary di-functional, and tri-functional Jeffamines were used. Glass transition temperatures were measured by DSC and five of six tested blends showed only one glass transition temperature, suggesting complete miscibility. All samples resulted in optically transparent blends, but displayed variant mechanical properties. Rheology data suggests that the samples behave as viscoelastic liquids at low frequencies, exhibiting properties that are in between the liquid Jeffamine and solid PS. The polymer blends prepared in this research support ionic complexation as a method of miscibility enhancement.