Stilbene-based liquid crystalline and photocrosslinkable polynaphthylphosphate esters

Abstract

A series of liquid crystalline and photocrosslinkable polymers were synthesized from 4,4′-bis(m-hydroxyalkyloxy)stilbene (m = 2, 4, 6, 8, 10) with naphthylphosphorodichloridate. The synthesized polymers were characterized by spectroscopic techniques. Thermogravimetric analysis revealed that the polymers were stable between 283 and 341 °C, then underwent two-stage decomposition, and char yield increased with decreasing spacer length. DSC and HOPM analysis disclosed that the polymers III–V (m = 6, 8, 10) exhibited LC phases wherein flexible methylene spacer separates mesogenic alignment and reduces overall rigidity of polymers, while polymers I and II are unable to show LC phase. The photolysis was studied by UV–visible and fluorescence spectroscopy. The rate of photocrosslinking increases with increase in methylene chain. The fluorescence property decreased with successive UV irradiation in the polymers.