Soluble Polyarylates Based on Methyl-substituted Bisphenols Containing Pendent Biphenyl Moiety: Synthesis, Characterization, and Thermal Properties

A series of polyarylates (PARs) containing pendent biphenyl moiety was synthesized via interfacial polycondensation polymerization from a mixture of three aromatic diols (4,4 '-[1-(4-biphenylyl)ethylidene] bisphenol (BBP), 4,4 '-[1-(4-biphenylyl)ethylidene]-bis,3-methyphenol (oBBP) and 4,4 '-[1-(4-biphenylyl)ethylidene]bis,3,5-dimethylphenol (dmBBP)) with molar equivalent of terephthaloyl chloride (TC). The synthesized PARs (coded as BBP-TC, oBBP-TC, and dmBBP-TC) showed excellent thermal properties and solubility in common organic solvents as the incorporation of pendent biphenyl moiety. The inherent viscosity of PARs was in the range of 0.50-0.71 dl/g, while the number average molecular weights (Mn) were found in the range of 30,213-35,112 g/mol. All the PARs showed glass transition temperatures (T(g)s) between 201 degrees C to 278 degrees C. The oBBP-TC observed low T-g as containing asymmetric dimethyl substitution, while other BBP-TC and dmBBP-TC were found normal T(g)s due to symmetrical structure with and without methyl substitution. The 10 % weight loss degradation temperatures of PARs were found to be in the range of 395-423 degrees C. X-ray diffraction studies of polyesters showed that all the PARs were amorphous. The mechanical and optical properties of films were also analyzed to understand the desirability of PARs in further applicability. With regards to its solubility, thermal stability, mechanical properties, and optical properties, these PARs may be considered as a promising material in the field of processable high-performance engineering.