Polycarbonate compositions having improved barrier properties

Claim 1

A halogen-free high molecular weight aromatic polycarbonate compound having an IV of about 0.40-1.0 dl/g in methylene chloride at 25° C. and exhibiting improved water vapor transmission and gas barrier properties, said polycarbonate compound consisting essentially of the following general repeating unit: ##STR7## wherein the X and Y moieties can each independently be selected from the group consisting of hydrogen, an unsubstituted alkyl of C 1 -C 10 , and mixtures thereof with the proviso that at least either X or Y is a C 1 -C 10 alkyl and that neither a cyclic nor an aryl group is bonded directly to a phenyl group; n is an integer of about 2-2,000; and, W is a member selected from the following group: (a) --CH 2 ) r wherein r is 0 or an integer from 2-10; (b) ##STR8## wherein R is a member selected from the group consisting of C 1 -C 10 alkyl, C 5 -C 10 cycloalkyl and C 6 -C 14 aryl; (c) ##STR9## wherein R and R' can each independently be the same as R in (b) above with the proviso that when both R and R' are each CH 3 , X and Y are not both symmetrically substituting CH 3 ; (d) ##STR10## wherein m is an integer of 4-20; (e) ##STR11## wherein p and q can each be an integer of 0-1; and, (f) --O--.