Cyclo-depolymerization of poly(propylene terephthalate): some ring-opening polymerizations of the cyclic oligomers produced

We report the cyclo-depolymerization of poly(propylene terephthalate) to give a mixture of cyclic oligomers in 94% yield, the characterization of the mixture by ¹H-NMR spectroscopy, matrix assisted laser desorption ionization time of flight mass spectrometry and gel permeation chromatography. The major cyclic oligomer in the mixture was shown to be the cyclic dimer. It was isolated and its X-ray crystal structure determined. Some entropically-driven ring-opening polymerizations of the cyclic oligomers were carried out. So too were some copolymerizations using mixtures of the cyclic oligomers and those derived similarly from poly(ethylene terephthalate) and poly(butylene terephthalate). ¹³C-NMR spectroscopic analysis showed that the copolymers were random. Copyright © 2003 John Wiley & Sons, Ltd.