Polymerization induced phase separation (PIPS) is a process in which homogeneous monomer resins form chemically heterogeneous polymeric materials with nano, micro and macroscale morphology. PIPS is an attractive approach for complex materials as it can minimize processing requirements associated with patterning of soft materials. To streamline the development of novel PIPS systems, however, it is necessary to identify prediction and screening tools that appropriately capture the underlying thermodynamic behavior, and more importantly can eliminate non-viable resin combinations. In this work we demonstrate that Hansen Solubility Parameters (HSPs) can be used to screen and predict solubility interactions of PIPS resins, focusing on the formation of phase separated polymers via free radical polymerization of a monomer in the presence of an inert prepolymer. Specifically, we use a modified ‘ternary diagram’ approach, where both mixing of the resin constituents as well as the extent of reaction are considered when assessing solubility relationships. We use our prior experimental work on the phase separation of acrylonitrile / poly(methyl methacrylate) materials to benchmark our predictions and narrow in on a few monomer / inert prepolymer combinations that are viable for further analysis. We experimentally validate the predictions provided by HSPs, and use the identified resin combinations to develop photopolymers with engineered wettability gradients. This approach is particularly valuable, as it saves time and resources when designing complex and heterogeneous polymeric systems.
