Polycondensation of p-xylylene dibromide and M2CO3 (M = Li, Na, K, Rb, and Cs) catalyzed by CuI gives polymer 1 which contains the p-xylylene carbonate structural unit, −CH2C6H4CH2O(CO)O− (a), and the p-xylylene oxide unit, −CH2C6H4CH2O− (b), randomly in the polymer chain. The use of Rb2CO3 and Cs2CO3 as the source of the carbonate group increases the yield of the polymer. Cu compounds including [Cu(C⋮CPh)(PPh3)]4, Cu(C⋮CC3H7), CuBr, CuBr2, and CuBr2(phen)n (phen = 1,10-phenanthroline, n = 1,2) also catalyze the polycondensation to give a product rich in unit a. The polycondensation catalyzed by alkynylcopper(I) complexes with or without addition of 1,10-phenanthroline gives a polymer with a high content of unit a (>95%). Polymer 1 possesses CH2OH terminal groups which are identified by 1H and 13C{1H} NMR as well as by reaction with an alkyl isocyanate. Reactions of 1 with diisocyanates such as 4-methyl-1,3-benzenediisocyanate, m-xylylene diisocyanate, and 1,6-hexanediisocyanate cause the polyaddition of ...