Self Assembly of Block Copolymers in Ionic-liquid Cured Epoxy*

In this work, the ability of ionic liquids to act as both a structure directing and curing agent in epoxy/block copolymer (BCP) blends is discussed. The material system consists of a bisphenol-A epoxy monomer, an ionic liquid hardener and an ABA triblock copolymer. These materials were analyzed via small angle x-ray scattering (SAXS) before and after thermal curing. Both the cured and uncured materials show a surprising variety of well-ordered and self-assembled phases which are not present in systems cured with traditional diamine curing agents. A ternary phase diagram was constructed to explore to effect of composition on observed phases. Phase changes as a function of temperature were observed via simultaneous thermal curing and in-situ SAXS. A number of order-order phase transitions were observed. The observed phases are sensitive to temperature even at temperatures well below the curing temperature of the epoxy, and thus are a function of both degree of epoxy crosslinking and free energy changes due to temperature.