New aromatic copolyesters were synthesized by phase-transfer catalyzed interfacial polycondensation of 4,4 `-((3,4-dimethoxyphenyl)methylene)bis(2-methoxyphenol) (DMBM) with isophthaloyl chloride (IPC) and a mixture of (50:50 mol %) IPC and terephthaloyl chloride (TPC). Additionally, a series of copolyesters was synthesized by polycondensation of varying compositions of DMBM and bisphenol A with IPC. Copolyesters exhibited inherent viscosity and Mn values in the range 0.59-0.98 dL/g and 15,840-49,460 g/mol, respectively, indicating formation of reasonably high molecular weight polymers. Copolyesters could be cast into tough, transparent and flexible films from chloroform solution. UV-vis measurements on films gave values of T400, T450 and cut-off wavelength in the range 80-84 %, 83-89 % and 324-334 nm, respectively. The formation of random copolyesters was evidenced by 13C NMR spectroscopic studies. Copolyesters exhibited good thermal stability with 10% weight loss temperature in the range 391-438 degrees C. The Tg values of copolyesters were in the range 162-180 degrees C and Tg values decreased with an increase in mol% content of DMBM. Copolyesters exhibited tensile strength, Young's modulus and elongation at break values in the range 83.55-70.68 MPa, 2.11-1.31 GPa and 10.52-5.45 %, respectively.

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