Alignment Layer of Liquid Crystal Using Plant-Based Isoeugenol-Substituted Polystyrene

We synthesized a series of renewable and plant-based isoeugenol-substituted polystyrenes (PIEU#, # = 100, 80, 60, 40, and 20, where # is the molar percent content of isoeugenol moiety), using polymer modification reactions to study their liquid crystal (LC) alignment behavior. In general, the LC cells fabricated using polymer film with a higher molar content of isoeugenol side groups showed vertical LC alignment behavior. This alignment behavior was well related to the surface energy value of the polymer layer. For example, vertical alignments were observed when the polar surface energy value of the polymer was smaller than approximately 3.59 mJ/m(2), generated by the nonpolar isoeugenol moiety with long and bulky carbon groups. Good alignment stability at 100 degrees C and under ultraviolet (UV) irradiation of 15 J/cm(2) was observed for the LC cells fabricated using PIEU100 as a LC alignment layer. Therefore, renewable isoeugenol-based materials can be used to produce an eco-friendly vertical LC alignment system.

Automated summary

A series of renewable and plant-based isoeugenol-substituted polystyrenes were synthesized to study their liquid crystal alignment behavior, showing that higher molar content of isoeugenol side groups resulted in vertical LC alignment. The surface energy value of the polymer layer played a key role in determining the alignment behavior. Good alignment stability was observed at high temperature and under UV irradiation for LC cells fabricated using PIEU100, demonstrating the potential of renewable isoeugenol-based materials in producing eco-friendly vertical LC alignment systems.