C. Koning et al., Synthesis and physical characterization of poly(cyclohexane carbonate), synthesized from CO2 and cyclohexene oxide, POLYMER, 42(9), 2001, pp. 3995-4004
Using [Zn(2,6-difluorophenoxide)(2)](2) (THF)(2) as the catalyst, poly(cycl
ohexane carbonate) (PCHC) was synthesized from CO2 and cyclohexene oxide. T
he ether content of the polymer was limited to a few mol%. The molecular we
ight distribution of the linear polycarbonate was broad, with M-n = 42 and
M-w = 252 kg/mol. The recorded T-g was 115 degreesC, which is in excellent
agreement with the reported value of 116 degreesC. In spite of its high mol
ar mass, PCHC behaves like a brittle polymer, with an elongation at break o
f 1-2%. On the other hand, the tensile modulus of PCHC (3600 MPa) is much h
igher than the corresponding value for bisphenol-A polycarbonate (BP-A PC)
(2400 MPa). Like the extremely tough BP-A PC, the PCHC exhibits a gamma -tr
ansition around -110 degreesC, the presence of which has been related to to
ughness. The magnitude of this gamma -transition is lower than the correspo
nding value for BP-A PC, which indicates that the main chain of PCHC is les
s flexible than that of BP-A PC. Moreover. the low temperature relaxation o
f PCHC is probably related to chair-chair transitions of the cyclohexane si
de group. The brittle behavior of PCHC is expected from the relatively low
plateau modulus of PCHC in the melt, from which a relatively high average m
olecular weight between entanglements (M-e) of ca. 15,000 g/mole was estima
ted, which is in the same order of magnitude as the M-e of the brittle poly
styrene. (C) 2001 Elsevier Science Ltd. All rights reserved.