Computational Insight into Phase Separation of a Thiol-Ene Photopolymer with Liquid Crystals for Holography by Dissipative Particle Dynamics Simulation

Holographic polymer nanocomposites comprising liquidcrystals (LCs)are produced through periodic photopolymerization-induced phase separationupon laser interference. A high degree of phase separation normallyfavors the holographic function which is, however, difficult to predict.Herein, we demonstrate the first example of providing computationalinsights into the phase separation by dissipative particle dynamicssimulation. Phase separation to produce alternating polymer-rich andLC-rich regions occurs in the way that LC molecules transfer frombright to dark regions upon laser interference when the thiol-eneclick reaction takes place in the bright regions. Results show thatthe relative segregation degree (SDr) increases with LCcontent when it is lower than 40 wt %, which can be correlated withthe transferred amount of LC molecules from bright to dark regions.The low SDr of the system with 40 wt % LC may be ascribedto the inhibitory LC transfer by polymerization compared with thecase prior to reaction. In terms of the effects of reaction probability,either too high or too low reaction probability is not favorable forphase separation due to insufficient LC transfer. Despite that nonematic LC phase is found after phase separation, this work providesinitial computation insights into the mass transfer behaviors duringphotopolymerization-induced phase separation, which help in the developmentof effective strategies to improve the phase separation and performanceof holographic polymer nanocomposites.