Viscoelastic Properties of Poly(methyl methacrylate) with High Glass Transition Temperature by Lithium Salt Addition

The effect of ion-dipole interaction between lithium cations and oxygen atoms in poly(methyl methacrylate) (PMMA), which leads to the great enhancement of glass transition temperature (T-g), on the linear viscoelastic properties is studied using binary blends of PMMA and lithium trifluoromethanesulfonate (LiCF3SO3). The strong interaction at low temperature leads to the high modulus in the glassy region even near T-g. The interaction becomes weak as increasing the temperature. Consequently, the rheological terminal region is clearly detected without a marked enhancement of steady-state compliance, although the zero-shear viscosity increases by the LiCF3SO3 addition. The result indicates that the crosslinking due to the ion-dipole interaction has a lifetime that decides the longest relaxation time. (C) 2016 Wiley Periodicals, Inc.