Effect of polymer binder on surface texturing by photoembossing

► Relief height in PMMA–DPPHA films of high aspect ratio are created by photoembossing. ► New mixtures for photoembossing are presented, containing greater monomer content. ► At high monomer contents, mixtures are solid at room temperature allowing mask exposure. ► Greater material flux during photo-polymerisation. ► This results in an increase in relief height by 50%. 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 (60wt.%), 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%.