Simulation of pseudopolyrotaxane formation and orientational order between pseudopolyrotaxanes.

We have performed Brownian dynamics simulations in order to investigate the formation of a pseudopolyrotaxane (PPRX) with cyclodextrins (CDs) and a polymer chain and the development of orientational order between PPRXs. The coarse-grained model is used to model the CDs and the polymer chain. In our simulations, we observe the formation of a rodlike PPRX with up to six rings for 40 monomer chains. After the formation of the PPRX, the processes of inclusion and dissociation repeat for the rings at the end of the chain. However, the PPRX has more than three rings and maintains the rodlike shape. With regard to the motion of rings in the PPRX, we observe two kinds of motions--oscillating motion and shifting motion. In the oscillating motion, the rings move around a particular position on the chain and display thermal fluctuation and collisions with neighboring rings. In the shifting motion, all rings shift to another location along the chain during the processes of inclusion and dissociation. In our simulations, we also observed that the orientational order between PPRXs develops at low temperatures.