SYNTHESIS AND POLYMERIZATION OF BIS(HEXAMETHYLENE CARBONATE) AND BIS(2,2,3,3,4,4,5,5-OCTAFLUOROHEXAMETHYLENE CARBONATE)

Bis(hexamethylene carbonate) (HC) and bis(2,2,3,3,4,4,5,5-octafluorohe xamethylene carbonate) (FHC) were synthesized starting from the corres ponding diols and diphenyl carbonate in a two-step reaction: (i) first polycondensation occurs, (ii) then ring-closing depolymerization lead s to HC and FHC, respectively. The polymerization of HC is performed w ith sec-butyllithium in toluene solution, and the corresponding polyme r is obtained in high yield. Polymerization of FHC is perfomed either in tetrahydrofuran solution with dibutylmagnesium as initiator or in t he melt with dibutyltin dimethoxide as initiator. Poly(HC) is a semicr ystalline polymer with a melting point of 54.0 degrees C and a glass t ransition temperature of -51.3 degrees C. Poly(FHC) was obtained eithe r as a semicrystalline material with a melting point of 40.8 degrees C or an amorphous material with a glass transition temperature of -39.8 degrees C. Copolymers of HC and FHC with a diad ratio of 19:60:21 wer e obtained by melt polymerization with dibutyltin dimethoxide as initi ator. The ring-chain equilibrium established during polymerization was studied for HC in toluene solution and for FHC in the melt. The conce ntration of the cyclic oligomers at equilibrium was determined, and fo r poly(HC) the characteristic ratio was calculated to be 10.0 +/- 1.0.