Synthesis and polymerization of bis(hexamethylene carbonate) and bis(2,2,3,3,4,4,5,5‐octafluorohexamethylene carbonate)

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Abstract
Bis(hexamethylene carbonate) (HC) and bis(2,2,3,3,4,4,5,5‐octafluorohexamethylene carbonate) (FHC) were synthesized starting from the corresponding diols and diphenyl carbonate in a two‐step reaction: (i) first polycondensation occurs, (ii) then ring‐closing depolymerization leads to HC and FHC, respectively. The polymerization of HC is performed withsec‐butyllithium in toluene solution, and the corresponding polymer is obtained in high yield. Polymerization of FHC is perfomed either in tetrahydrofuran solution with dibutylmagnesium as initiator or in the melt with dibutyltin dimethoxide as initiator. Poly(HC) is a semicrystalline polymer with a melting point of 54.0°C and a glass transition temperature of −51.3°C. Poly(FHC) was obtained either as a semicrystalline material with a melting point of 40.8°C or an amorphous material with a glass transition temperature of −39.8°C. Copolymers of HC and FHC with a diad ratio of 19:60:21 were obtained by melt polymerization with dibutyltin dimethoxide as initiator. The ringchain equilibrium established during polymerization was studied for HC in toluene solution and for FHC in the melt. The concentration of the cyclic oligomers at equilibrium was determined, and for poly(HC) the characteristic ratio was calculated to be 10.0 ± 1.0.