Polyesters and polycarbonates are remarkable polymers having complex chemical structures widely used as materials in society spanning a wide range of applications. Chemically modified co-polymers of polyesters, polycarbonates and homo-polyestercarbonates are studied for their iso-energy contours of torsion angles at the bond-pair level as well as chain properties at high molecular weights for the first time via classical molecular mechanics, RIS theory and Monte Carlo simulations, at different temperatures. Results obtained for the torsion angles and chain dimensions such as &lt;r2&gt;, &lt;s2&gt;, Cn and persistence lengths of polyestercarbonate containing para-phenylene (PECT) and meta-phenylene (PECI) fragments, copolyester of bisphenol A and benzophenone dicarboxylic acid (BPA-BDA), alternating and random co-polycarbonate of bisphenol A and hydroquinone (BPA-HQ) were compared to those for well-known polymers BPAPC, PET, and PEI. Unperturbed chains of 50:50 proportion of units for random co-polycarbonates and the two esters for the homopolyester carbonates were also investigated. PECT is more extended than PECI due to the presence of terephthalate linkage in the former. Higher chain dimensions are exhibited by PECT as compared to BPAPC and PET. PECI which contains the isophthalate group has compact coil structure and reduced conformational dimensions compared to PECT. The qualitative differences in the chain conformations between PECT and PECI is in agreement with observed experimental behaviour in literature. Copolyester BPA-BDA is more compact compared to PECT and is more extended than PECI. PECT is more extended than BPA-BDA. BPA-H copolycarbonate has higher characteristic ratio than BPAPC. As compared to nearly free (energy barrier) rotation about phenyl-oxygen bond in BPAPC there is impeded rotation at this bond in the case of BPA-HQ copolycarbonate. Among the random copolyesters and alternating copolyesters PECI is more extended compared to PECI. The data obtained here suggest that alternating copolyesters PECT and PECI have more extended dimensions than the random copolymers due to the blocks of random copolymers containing segment linkages of statistical nature. Characteristic-ratio of PECT is much greater than PECI and BPA-H. Persistence length of PECT is much greater than that of PECI and BPA-H which have similar persistence length. Implications of results on strength of polymer material will be discussed.

Conformational analysis, RIS models, chain structures and dimensions of homopolymers, alternating and random co-polymers, of polycarbonates, polyesters and polyestercarbonates

ACS Fall 2021

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