聚对苯二甲酸丁二醇酯二聚体键离能的理论研究

采用密度泛函理论方法对聚对苯二甲酸丁二醇酯(PBT)二聚体的键离能进行了计算.为了选取较为精确的方法来计算PBT各个键的键离能，以与PBT具有相同的酯基官能团的乙酸乙酯为模型参照物.采用M062X, B3P86, M06, PBE0, wB97xD方法分别在基组6-31G(d), 6-311G(d), 6-311+G(d, p), 6-311++G(d, p), cc-pVDZ, cc-pVTZ水平下对乙酸乙酯的键离能进行计算.通过对比计算结果与iBonD数据库的乙酸乙酯实验测定值可知，M062X在基组6-311G(d)水平下计算结果与实验值最为接近.因此，本研究采用M062X方法在基组6-311G(d)水平下对聚对苯二甲酸丁二醇酯(PBT)二聚体的键离能进行计算.计算结果表明：在PBT的各键中C-C_arcmatic键的键离能最大，主链上的C-C键离能最小，为370.9 kJ/mol.其次就是C-O键，为404.6 kJ/mol.基于PBT键离能的计算结果，设计了3条PBT二聚体热降解过程可能形成的反应路径，分析了热解产物的形成机理.结果表明PBT二聚体热解过程可...

Theoretical study on the bond dissociation energy of polybutylene terephthalate dimer

The density functional theory method was used to calculate the bond dissociation energy of polybutylene terephthalate (PBT) dimer. In order to select a relative accurate method to calculate the bond dissociation energy of PBT, the ethyl acetate, which has the same ester functional group as PBT, was selected as the model reference to calculate the bond dissociation energies by using M062X, B3P86, M06, PBE0 and wB97xD methods with the basis sets of 6-31G(d), 6-311G (d), 6-311+G(d, p), 6-311++G(d, p), cc-pVDZ and cc-pVTZ, respectively. By comparing the calculated results with the measured values of the ethyl acetate experiment in the iBonD database, it can be seen that the calculated results of M062X at the level of 6-311G(d) basis set are closest to the experimental values. Therefore, the M062X method was used to calculate the bond dissociation energy of PBT dimer at the level of 6-311G(d) basis set in this study. The calculated results show that the C-Carcmatic bond has the largest bond dissociation energy among the bonds of PBT, the bond dissociation energy of C-C bond on the main chain is the smallest, which is 370.9 kJ/mol, followed by the C-O bond, which is 404.6 kJ/mol. Based on the calculated results of the dissociation energy of the PBT, three possible reaction paths during the thermal degradation of the PBT dimer are designed, and the formation mechanism of the pyrolysis products was analyzed. The results indicate that the pyrolysis process of PBT dimer may mainly undergo a concerted reaction.