Thermal analysis of ampholytic polymers

• Published in: Journal of Polymer Science Part C: Polymer Letters 1987-05, Vol.25 (5), p.201-203
• Main Authors: Neculescu, C., Clough, S. B., Elayaperumal, P., Salamone, J. C., Watterson, A. C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Exact sciences and technology; Ionization properties; Organic polymers; Physicochemistry of polymers; Properties and characterization
• ISSN: 0887-6258; 0360-6384; 1543-0472
• DOI: 10.1002/pol.1987.140250501

A large number of studies have been concerned with the effect of ion concentration on the glass transition temperature T sub g in ionomers. Generally, an increase in T sub g is noted with increasing ion concentration. A recent paper compares differential scanning calorimetry (DSC) results for sulfonated polystyrene and polystyrene-co sulfonate. For the latter polymer, a step increase in dq/dt at the principal T sub g near 100 deg C was followed by a second small step increase near 250 deg C. This higher transition was attributed to an ion rich phase. Additional DSC studies on sulfonated polystyrene ionomers showed an apparent endothermic peak at the glass transition on samples aged below T sub g . The peak was believed to be due to internal stresses caused by reorganization during aging due to the electrostatic interactions. A usual step increase in dq/dt was observed for samples which were not aged. Dynamic mechanical methods have often been used to obtain data on transitions in ionomers. In many cases, two loss peaks have been reported, one at the principal glass transition followed by a higher temperature T sub g peak for regions where ions have clustered. Such results were obtained, for example, on lithium salts of ethyl acrylate--acrylic acid copolymers, and sodium salts of several styrene ionomers. 10 ref.--AA