The polyaddition of bis(oxetane)s 1,4-bis[(3-ethyl-3-oxetanylmethoxymethyl)]benzene (BEOB), 4,4'-bis [(3-ethyl-3-oxetanyl)methoxyl benzene (4,4'-BEOBP), 1,4-bis[(3-ethy-3-oxetanyl)methoxyl -benzene (1,4-BEOMB), 1,2-bis[(3-ethyl-3-oxetanyl)methoxy]benzene (1,2-BEOMB), 4,4-bis[(3-ethyl-3-oxetanyl)methoxy]biphenyl (4,4'-BEOMB), 3,3',5,5'-tetramethyl-[4,4'-bis(3-ethyl-3-oxetanyl)methoxy]biphenyl (TMBEOBP) with active diesters di-s-phenylthioterephthal ate (PTTP), di-s-phenylthioisoterephthalate (PTIP), 4,4'-di(p-nitrophenyl)terephthalate (NPTP), 4,4'-di(p-nitrophenyl)isoterephthalate (NPIP) were carried out in the presence of tetraphenylphosphonium chloride (TPPC) as a catalyst in NMP for 24 h, affording corresponding polyesters with M.'s in the range 2200-18,200 in 41-98% yields. The obtained polymers would soluble in common organic solvents and had high thermal stabilities. (C) 2004 Wiley Periodicals, Inc.