The intermolecular rotational potential energies for poly(dimethylsiloxane) (PDMS) chains are directly obtained from a priori probability P-alpha beta. Here the differing statistical weight matrices for the Si-O and O...The intermolecular rotational potential energies for poly(dimethylsiloxane) (PDMS) chains are directly obtained from a priori probability P-alpha beta. Here the differing statistical weight matrices for the Si-O and O-Si bonds are considered in calculating the configuration partition function. In the Bahar's model, as the same statistical weight matrices for the Si-O and O-Si bonds are adopted, there exists a large deviation of a priori probability P-alpha beta between the theory and the molecular dynamics (MD) simulation. Our model gives satisfactory agreement with experiment on the mean-square unperturbed end-to-end distance, the mean-square dipole moment and its temperature dependence, and the molar cyclization equilibrium constants for dimethylsiloxane oligomers. This new rotational isomeric state approach can be widely applied to other chains; such as -CH2-C[(CH2)(m)H](2)- and -O-Si[(CH2)(m)H](2) for arbitrary m.展开更多
基金This research was financially supported by National Natural Science Foundation of China and the National Basic Research Project"Macromolecular Condensed State"from STCC.
文摘The intermolecular rotational potential energies for poly(dimethylsiloxane) (PDMS) chains are directly obtained from a priori probability P-alpha beta. Here the differing statistical weight matrices for the Si-O and O-Si bonds are considered in calculating the configuration partition function. In the Bahar's model, as the same statistical weight matrices for the Si-O and O-Si bonds are adopted, there exists a large deviation of a priori probability P-alpha beta between the theory and the molecular dynamics (MD) simulation. Our model gives satisfactory agreement with experiment on the mean-square unperturbed end-to-end distance, the mean-square dipole moment and its temperature dependence, and the molar cyclization equilibrium constants for dimethylsiloxane oligomers. This new rotational isomeric state approach can be widely applied to other chains; such as -CH2-C[(CH2)(m)H](2)- and -O-Si[(CH2)(m)H](2) for arbitrary m.
