POLYMERS OF CARBONIC-ACID .19. HIGH-MOLECULAR-WEIGHT POLY(OCTAMETHYLENE CARBONATE) BY RING-OPENING POLYMERIZATION WITH BUSNCL(3) OR SNOCT(2)

Cyclobis(octamethylene carbonate), (OMC)(2), was synthesized by polyco ndensation of 1,8-octanediol with diethyl carbonate and subsequent the rmal depolymerization in vacuo. Two series of polymerizations were con ducted in bulk at 140 degrees C with BuSnCl(3) as the initiator. Eithe r the reaction time was varied at a constant monomer/initiator (M/I) r atio or the M/I ratio was varied at constant time. Two analogous serie s of polymerizations were conducted with Sn(II) 2-ethylhexanoate, SnOc t(2) as the initiator. Both initiators proved almost equally reactive, but the highest yields (up to 97%) and the highest molecular weights (M(w) up to 95 000) were obtained with BuSnCl(3). Both initiators yiel ded a polyOMC free of ether groups. The polyOMC samples prepared with SnOct(2) contain CH2OH and octoate end-groups. DSC measurements reveal ed that polyOMC is a rapidly crystallizing polymer with a melting temp erature (T-m) of 66 +/- 1 degrees C. Thermogravimetric analyses in nit rogen showed a maximum rate of degradation at 350 degrees C with forma tion of CO2, but without formation of formaldehyde, cyclic ether, or m onomeric cyclocarbonate.