Influence of substrate surfaces on thermal behavior of photopolymerization-induced phase separation of liquid crystal and polymer

We studied photopolymerization-induced phase separation (P-PIPS) of polymer fibers and liquid crystal (LC) formed at various thicknesses between glass substrates using a differential scanning calorimeter to find the influence of substrates on the P-PIPS phenomenon. In this case, the energy of ultraviolet light adsorbed by the solution film of the LC and monomer was kept constant in a unit area even when the solution thickness was changed. As an experimental result, the thermal phase-transition sequence behavior of the LC component in the formed composite film of smaller thickness approached that of the original pure LC. The total reaction heat for the polymerization in any thickness solutions did not make meaningful difference. These indicate that the phase separation can be promoted by decreasing the distance between the substrates even under constant polymerization degree, which depends on the polymerization reaction.