Session XC13 - Polyelectrolytes in Thin Films.
ORAL session, Friday morning, March 26
Room 267W, GWCC
To investigate the effect of ionic cross-links on the mechanical properties of polymer blends, we have studied the deformation behavior and mechanical properties of poly(styrene-co-styrenesulfonic acid)/poly(styrene-co-4-vinylpyridine) blends. FTIR investigation revealed that ionic cross-links due to ion-ion interactions were formed between the component polymers upon blending, which arises from the proton transfer from sulfonic acid groups to pyridine groups. TEM observation of strained thin films indicated that the deformation behavior of the blends changed from crazing only to crazing plus shear deformation with an increase of the interacting group content, from 1.0 molchanges can be understood as arising from an increased "effective" strand density due to the formation of ionic cross-links upon blending. Tensile tests showed that mechanical properties of the blends exhibited a synergistic enhancement, i.e., average values of toughness and tensile strength were higher than those expected based on the rule of mixtures, and both of them increased with the interacting group content. This is in contrast to miscible neutral blends, in which the strand density is only the average of values for the component polymers and the mechanical properties generally exhibit little or no synergistic enhancement.