Separation of oligomers from poly(vinyl chloride) by coupled column chromatography

A multistage scheme was developed for the separation of vinyl chloride (VC) oligomers. A low-molecular-weight fraction was isolated from poly(vinyl chloride) by Soxhlet extraction with diethyl ether followed by fractional precipitation with n-pentane. The presence of VC oligomers up to decamer was demonstrated by high-performance gel permeation chromatography (HPGPC). Removal of polar impurities was accomplished by preparative adsorption liquid chromatography of the low-molecular-weight fraction. Recycle HPGPC with repeated injections permitted the accumulation of fractions of VC pentamer oligomers which were resolved into their isomers by high-performance liquid chromatography (HPLC) off-line. These results were duplicated utilizing a coupled column system comprising of recycle HPGPC connected on-line to HPLC. This coupled technique was then applied to the hexamer and heptamer oligomers which were resolved into their constituent isomers.