Photopolymerization-induced phase separation of PEO, PPO and PEO-PPO-PEO in photo-curable monomers in confined film geometry*

Polymerization-induced phase separation in photo-initiated polymerization can serve as a useful strategy for fabricating 3D printed porous structures in stereolithography. While polymer can remain miscible with photocurable monomers, the phase separation will be eventually triggered by the polymerization to convert the low molecular weight monomers into polymer networks. We have compared the difference in the morphological development of polymerization-induced phase separation when different types of polyethers are used as phase separation additives in the photocurable (meth)acrylate monomers. In particular, poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO) and PEO-b-PPO-b-PEO are examined as the polyethers. This series of polymers have been chosen in the experimental design because of their differential incompatibility with (meth)acrylate monomer systems, as well as their easily removable properties using alcohol to create porous structural polymer networks. Optical and electron microscopy techniques are used to investigate the morphology, while the real-time light transmission measurements have been utilized for the in-situ monitoring of the photopolymerization-induced phase separation.