The ring-expansion reaction of equimolar cyclic dithioester 1 with 3-phenoxypropyrene sulfide (PPS) (cyclic dithioester 1/PPS ) 1/2) was examined in the presence of TBAC as a catalyst in NMP for 24 h. It was found that intermolecular ester-exchange reaction occurred during the insertion reaction of PPS into cyclic dithioesters, and cyclic polymers with M ns ) 3600-8900 were obtained in 80-96% yields. The structures of the obtained cyclic polymers were confirmed by the 1 H NMR, 13 C NMR IR, and MALDI TOF-MS spectroscopy. The continuous insertion reaction of excess PPS into cyclic dithioester (cyclic dithioester 1/PPS ) 1 /50) was also examined, and it was found that the insertion reaction proceeded quantitatively to afford the corresponding cyclic polysulfide with M n ) 42 000 and Mw/Mn ) 4.50 in a 96% yield.
The ring-crossover polymerization of cyclic dithioester 1 was performed in the presence of quaternary onium salts as catalysts at 70-150 8C for 24 h in NMP. It was found that predictable cyclic polymers with the same repeating structures as 1 were obtained with M n s in the range between 700 and 3,500, quantitatively. It was observed that intermolecular and intramolecular thioester-exchange reactions proceeded between cyclic monomer 1 and resulting cyclic polymers under thermodynamic control to give a lower-molecular-weight cyclic polymer with a lower polydispersity ratio (M n ¼ 2,400, M w /M n ¼ 1.70). V V C 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 680-687, 2007
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