Aromatic polyesters are of considerable interest because of their excellent mechanical properties, chemical resistance and thermal stability. However, most aromatic polyesters are difficult to process due to their high glass transition temperatures coupled with their insolubility in common organic solvents. The present article describes a series of organosoluble polyesters and copolyesters based on 1,1,1-[bis(4-hydroxyphenyl)-4'-pentadecylphenyl]ethane. A series of new aromatic polyesters containing pendant pentadecyl chains was synthesized by interfacial polycondensation of 1,1,1-[bis(4-hydroxyphenyl)-4'-pentadecylphenyl]ethane with terephthalic acid chloride (TPC), isophthalic acid chloride (IPC) and a mixture of TPC and IPC. A series of copolyesters was synthesized from 4,4'-isopropylidenediphenol with TPC by incorporating 1,1,1-[bis(4-hydroxyphenyl)-4'-pentadecylphenyl]ethane as a comonomer. Inherent viscosities of the polyesters and copolyesters were in the range 0.72-1.65 dL g(-1) and number-average molecular weights were in the range 18 170-87 220. The polyesters and copolyesters containing pendant pentadecyl chains dissolved readily in organic solvents such as chloroform, dichloromethane, pyridine and m-cresol and could be cast into transparent, flexible and apparently tough films. Wide-angle X-ray diffraction data revealed the amorphous nature of the polyesters and copolyesters. The formation of loosely developed layered structure was observed due to the packing of pendant pentadecyl chains. The temperature at 10% weight loss, determined using thermogravimetric analysis in nitrogen atmosphere, of the polyesters and copolyesters containing pendant pentadecyl chains was in the range 400-460 degrees C. The polyesters and copolyesters exhibited glass transition temperatures in the range 63-82 degrees C and 177-183 degrees C, respectively. (C) 2010 Society of Chemical Industry