Molecular theory on the entanglement effect of rodlike polymers

The rotational diffusion constant Dr of entangled rodlike polymers in semidilute solution was calculated by our refining quantitatively the Doi-Edwards tube model. The methods of probability and stochastic process theory were used to calculate the mean lifetime of tubes, while the mean step angle of jump diffusion was evaluated by computer simulation on the size distribution of tubes. Our result eliminates a large discrepancy of Dr between the Doi-Edwards theory and a variety of experiments on rodlike polymers.