Formation of segmental clusters during relaxation of a fully extended polyethylene chain at 300 K: A molecular dynamics simulation

Molecular dynamics simulations were performed on the relaxation of fully ex tended polyethylene chains, varying in length from 600 to 4000 CH2 units. W hen a chain has more than 1200 CH2 units, the relaxation proceeds in three stages, subglobule formation, subglobule growth, and subglobule coalescence into one globule. In the stage of subglobule growth, the number of subglob ules is almost a constant because of kinetic barrier, which is different fr om the results based on Monte Carlo simulations of polymer collapse in dilu te solution. The difference of lamella thickness between MD simulations and experiments is discussed. The degree of adjacent reentry is calculated, an d amounts between 0.4 and 0.5 for the formed lamellae. (C) 1999 American In stitute of Physics. [S0021-9606(99)51614-0].