Rheological and Mechanical Properties of Poly(methyl methacrylate) Associated with Lithium Salts

Abstract

On the basis of the lithium electrolyte mechanism, modified glassy polymers were developed by adding lithium salts to poly(methyl methacrylate) (PMMA). This review summarizes how the rheological and mechanical properties of PMMA were changed by introducing various lithium salts: lithium perchlorate (LiClO₄), lithium trifluoroacetate (LiCOOCF₃), lithium trifluoromethanesulfonate (LiCF₃SO₃), lithium nonafluorobutanesulfonate (LiC₄F₉SO₃), and lithium bromide (LiBr). It was found that the rheological and mechanical properties of PMMA are dominated by the aggregation state of the salts in the matrix, the degree of bulkiness in anions, and anion size. This review focused on the “pinning” effect, which is attributed to the ion-dipole interaction between the lithium cations and PMMA molecular chains. This pinning effect was evaluated in the molten state during the molding, which directly affects the mechanical properties in the solid state. Therefore, the pinning, which depends on the anion species, affects not only the rheological and mechanical properties, but also the tensile properties of PMMA/Li-salts.