Polyoxometalate cured epoxy resins with photochromic properties
writer：Xinhui Zhong, Yi Liu, Xiaolin Tang, Qili Wu, Liang Li, Yingfeng Yu*
keywords：Epoxy resin, Photochromism . Polyoxometalate, Cationic polymerization
source：期刊
specific source：Colloid Polym Sci (2012) 290:1683–1693
Issue time：2012年
Novel photochromic thermosetting materials were facile prepared by polyoxometalate, Keggin type H3PW12O40, cured epoxy networks with ethylene oxide blocks. The dual functions of polyoxometalate as both hardener and photochromophore were studied by differential scanning calorimetry (DSC), infrared spectroscopy (IR), ultraviolet-visible spectroscopy (UV-vis) and generalized two-dimensional correlation analysis. Polyoxometalate initiates the cationic polymerization of epoxy resin through dissolving in either polyethylene oxide epoxy or organic solvents. When subjected to UV irradiation, the transparent thermosetting materials with ethylene oxide blocks change from colorless to blue, and could be bleached in air at various temperatures to recover its initial state. From the UV-vis measurements, all the resultant thermosetting materials demonstrated similar photochromic behavior after ultraviolet irradiation showing characteristic d-d transition band and intervalence charge transfer (IVCT) band. The 2D correlation analysis of the photochromic spectra clearly revealed the sequence of electron movements in the framework of PW12 anion.