Synthesis of bis(2,3-epoxycyclohexyl) and its cationic photopolymerization in the presence of different diols

BACKGROUND: An ester‐free cycloaliphatic di‐epoxide, bis(2,3‐epoxycyclohexyl), with epoxycyclohexyl moieties linked via carbon–carbon bonds was synthesized and characterized. The photopolymerization of the di‐epoxide was systemically investigated in the presence of different diols, 1,2‐ethanediol, 1,4‐butanediol, 1,2‐propanediol and pinacol, using real‐time Fourier transform infrared spectroscopy to follow the reaction process. RESULTS: Among the four diols, the presence of pinacol resulted in the fastest photopolymerization rate and highest degree of conversion of di‐epoxy groups, but a relatively low gel content, while the addition of 1,2‐ethanediol led to an inhibiting effect on the di‐epoxide reaction rate, but the product showed the highest gel content. The influences of the diols on the cationic photopolymerization behavior of the di‐epoxide were explained according to the steric hindrance, proton‐trapping ability and electronic effect of the diols. CONCLUSION: The study results provide the possibility to conveniently manipulate the photopolymerization rate and modify the properties of an epoxy resin by simply adjusting the structure and amount of added diol in the polymerization system to meet the demands for potential microelectronic and optoelectronic packaging applications. Copyright © 2008 Society of Chemical Industry