Relation between the amount of glycerol, glass transition temperature, and ion content of styrene-methacrylate ionomers

Abstract

In this study, the relation between the amount of a polar plasticizer, i.e. glycerol, and the glass transition temperature ( T g ) and ion content of the poly(styrene-Na methacrylate) (PSMANa) ionomers was investigated dynamic mechanically. Since glycerol affected the formation of ionic aggregates due to its polarity, the T g of ion poor matrix regions decreased slightly. On the other hand, the cluster T g ( T g,c ) was influenced by the amount of glycerol, the ion content of the ionomer, and the phase separation of glycerol in the ionomer matrix. Furthermore, the T g,c of plasticized ionomers was estimated by a simple equation as follows: 1/( T g,c (°C) – 7.1 × (15.7 – ion content (mol%))) (°C) = 1/(166 + 7.1 × ion content (mol%)) + 0.00025 × (wt% of plasticizer). In addition, the maximum amount of glycerol (wt%) before phase separation was simply expressed as 0.124 × (ion content (mol%)) 2 . The above results revealed that the T g,c of PSMANa ionomers could be controlled from above 300 °C to below 100 °C by changing the ion content of the ionomers and the amount of glycerol in the ionomers. • The ion content and the amount of glycerol control the cluster T g of the ionomer. • The maximum amount of glycerol depends on the ion content of the ionomer. • Macroscopic phase separation strongly influences the plasticization of ionomers.