Applying Hansen Solubility Parameters to Dynamically Reacting Systems─A Case Study of Photopolymerization Induced Phase Separation

Photopolymerization induced phase separation (PIPS) is a straightforward strategy for complex design, where homogeneous starting resins form chemically heterogeneous materials, overcoming limitations of traditional patterning approaches. To minimize resource waste when exploring undiscovered PIPS systems and applications, it is necessary to identify prediction and screening tools that appropriately eliminate nonviable resin combinations. Here we use Hansen Solubility Parameters (HSPs) as a screening strategy to predict solubility interactions of PIPS resin components at the initial and final stages of a reaction. With these two states in mind, the degrees of miscibility between available precursors (e.g., (co)monomers and polymer additives) can be leveraged to identify promising PIPS resin systems. We demonstrate that in using solubility parameters to inform PIPS resin design, HSPs can streamline resin formulation and exploration. We implemented this approach to create photopolymers with engineered wettability gradients.