Dynamic Mechanical Properties of Elastomeric Poly(n-Butyl Acrylate) Ionomers

Abstract

This research explored the impact of temperature on the mechanical properties of poly(n-butyl acrylate-co-Na methacrylate) (PBA) ionomers, as an elastomeric ionomer, with an emphasis on their ion content. The PBA ionomers were found to exhibit dual glass transition temperatures (T _gs) and ionic plateaus, characteristics typically observed in other amorphous ionomers. Significantly, in PBA ionomers, ionic aggregates (i.e., multiplets) functioned like chemical cross-linking points in addition to their conventional role as physical cross-links. This dual functionality resulted in an upward shift of the rubbery plateau and a consequent enhancement of storage moduli. In a comparative analysis of the mechanical properties of PBA, poly(ethyl acrylate) (PEA), and poly(styrene-methacrylate) (PSMA) ionomers, it was determined that the extent of ionomer clustering increased progressively from PBA ionomer to PEA ionomer to PSMA ionomer. The mechanical properties of these three ionomer systems were interpreted through the lens of multiplet formation mechanisms, with a particular focus on the quantity of multiplets and the number of ion pairs per multiplet, both of which were modulated by the matrix T _gs of each ionomer.