Comparison of the mechanical properties of styrene-based ionomers containing either crown ether or pentaethylene glycol with those of underneutralized ionomers

Abstract

Dynamic mechanical properties of styrene-based ionomers containing varying amounts of either 15-crown-5 ether (CE) or pentaethylene glycol (PG) are compared with those of ionomers of varying degree of neutralization (ND). The cluster Tg (Tg,c) and ionic modulus of the ionomers decrease with increasing amount of CE or PG or decreasing ND. Thus, we propose that the CE binds Na+ strongly to form a large-sized complex. Thus, the electrostatic interactions between charges decrease, leading to lower Tg,c. For the PG-containing ionomers, the PG acts as polar plasticizer, further lowing the Tg,c. In the case of the underneutralized ionomers, the Tg,c is reduced by the existence of both relatively weak hydrogen bonds between carboxylic acid groups and relatively strong ionic bonds between ion pairs in the multiplets. The small-angle X-ray scattering results are also supportive of the above interpretations. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 1358–1367