Mb. Hagg et al., GAS SORPTION AND TRANSPORT-PROPERTIES OF BISPHENOL-I-POLYCARBONATE, Journal of polymer science. Part B, Polymer physics, 32(9), 1994, pp. 1625-1633
Gas sorption and transport characterization of a new polymer in the po
lycarbonate family, based on the bisphenol of 3,3,5-trimethylcyclohexa
ne-1-one (BPI) is reported at 35-degrees-C. By comparison with propert
ies of other known polycarbonates, the effects of inhibition of both p
acking and segmental motion due to the introduction of the bulky subst
ituent in the backbone are elucidated. The T(g) of the material was me
asured with differential scanning calorimeter (DSC) and was found to b
e unusually high for a polycarbonate (233-degrees-C). This indicates a
successful inhibition of the large-scale segmental mobility of the po
lymer. Vari-able C-13 NMR analysis indicated that rotation of one phen
ylene ring has an unusually high (ca. 10 kcal) energy barrier, whereas
the other phenylene ring has a more typical rotation profile (barrier
< 3 kcal). The density was measured and found to be low (1.107 g/cm3)
, indicating a high fractional free volume (FFV) for the polymer. Cons
istent with expectations, the introduction of the bulky-substituted cy
clohexane group gave high permeabilities for the various gases tested
(N2, O2, He, CH4, CO2) compared to most standard polycarbonates. On th
e other hand, the permselectivities were typical for standard polycarb
onates. The solubility coefficients of all gases were rather high, as
expected for a polymer with such an open structure. (C) 1994 John Wile
y & Sons, Inc.