Effect of polymer binder on surface texturing by photoembossing

Photoembossing is a simple and versatile technique to create relief structures in polymers using a patterned contact mask exposure and a thermal development step. Typically, the photo-resist consists of a polymeric binder such as poly(benzyl methacrylate) (PBMA) and a multifunctional monomer in a 50/50 weight ratio and the mixture is a solid and non-tacky material at room temperature. Here, new mixtures for photoembossing are presented, which contain higher monomer content and therefore show greater material flux during photopolymerisation. These mixtures are solid at room temperature even at high monomer contents (60 wt.%), which is achieved by using a polymer binder with a higher glass-transition temperature (Tg) such as poly(methyl methacrylate) (PMMA). DSC experiments also indicated that the interactions between monomer and PMMA are less strong compared to PBMA. The combined effect of increased monomer content and weakened interactions with PMMA led to a greater mobility of the monomer and an increase in height of the relief structures by a 50%.