Structural Studies and Polymerization Mechanisms of Synthesized Lacquer Films Using Two-stage Pyrolysis-Gas Chromatography/Mass Spectrometry

Abstract

Two kinds of synthesized lacquer films were investigated and compared with a natural lacquer film using two-stage pyrolysis-gas chromatography mass spectrometry (Py-GC/MS). Monoenyl and saturated urushiol were detected from the synthesized lacquer film by pyroly-sis at 400°C, as well as from the natural lacquer film. These are attributed to the terminal groups of the synthesized lacquer film. In addition, alkenylphenois. aikyiphenols, alkenes and alkanes were detected by pyrolysis at 500°C after pyioiysis at 400°C. as well as in the natural lacquer film. Some alkenes and alkanes have longer carbon chains than the side chains of synthesized urushiol. The alkenylphenois and aikyiphenols are the pyrolysis products of the nucleus-side chain C-O coupling synthesized urushiol polymers, and the alkenes and alkanes, whose carbon chains are longer than the side chains of synthesized urushiol, are the pyrolysis products of autoxidative side chain-side chain C-C coupling synthesized urushiol polymer. Based on these results, it was found that the synthesized lacquer films are terminated with the monoenyl and saturated urushiol. and the polymerization of synthesized urushiol proceeds through the laccase-catalyzed nucleus-side chain C-O coupling and the autoxidative side chain-side chain C-C coupling like the natural lacquer film. Since the structure and polymerization mechanisms of the synthesized lacquer films are very similar to those of the natural lacquer film, these lacquer films must be tough and brilliant enough to be used as preservative surface coating materials like the natural lacquer film.