CYCLIC POLYESTERS .5. CYCLICS PREPARED BY POLY(DECAMETHYLENE TEREPHTHALATE) RING-CHAIN REACTIONS

Cyclic oligomers of poly(decamethylene terephthalate) (PDT) were prepa red successfully and cleanly from a ring-chain equilibrium reaction in dilute solution of chlorobenzene. A variety of catalysts were investi gated for this purpose. The reactions were monitored up to equilibrium and the molar cyclization equilibrium constants K-x deduced. Satisfac tory yields of cyclics [O(CH2)(10)OCOC6H4CO](x) were obtained, togethe r with a higher molar mass linear polymer. Mass spectroscopic investig ation showed that no monomeric ring was formed in the PDT reaction. Th e individual cyclics with x = 2-14 corresponding to 36-252 skeletal bo nds were completely resolved using PL-gel mixed-E gel permeation chrom atographic columns. The lower mass cyclics (x = 2-5) were cleanly extr acted and then characterized. The yield of cyclics in ring-chain equil ibrates corresponding to a solvent/polymer dilution ratio of 30/1, 60/ 1 and 100/1 were ca 11%, ca 30% and ca 50%, respectively. The K-x valu es for PDT cyclics were used to compare the statistical conformations of the corresponding PDT chains in chlorobenzene with an aliphatic pol yester, poly(decamethylene adipate), which was studied previously. (C) 1997 Elsevier Science Ltd.