Polymerization-induced diffusion as a tool to generate periodic relief : a combinatorial study

Polymeric relief structures are extensively used in display technology due to their ability to redirect light in a controlled way. Photo-embossing is a new photo-lithographic technique to generate surface relief structures using photopolymers. In the present paper we show a combinatorial methodology to explore this technique. We have prepared and evaluated (using automated atomic force microscopy) 2-dimensional libraries of photo-embossed gratings, each library with a gradient in period and a gradient in either exposure energy or development temperature or film thickness or photoinitiator concentration or monomer to binder ratio. We show how this combinatorial approach helps us to better understand the photo-embossing process. In addition, we show that this methodology is an effective tool to identify processing conditions resulting in optimum shape and height of the polymeric relief micro-structures to be used in specific applications.