Regular folding in solution‐grown polyethylene crystal, 1. Model description

Abstract

To re-consider the idea that a polymer chain should fold regularly rather than randomly, the pair s-chain crystalline growth philosophy was suggested. On the basis of this philosophy, the coordinated pair chain folding model (CPCFM) for polyethylene (PE) polymer single crystal is proposed, with the paired chain folding on average along the (110) plane of the orthorhombic crystal lattice and each of the coordinated pair chains folding alternatively at (100) and (010) planes. Being a regular folding model, the CPCFM explains most of the regular shapes of PE single crystals including lamellar diamond shape, flat based and non-flat based hollow pyramidal shapes, saddle shape, truncated diamond shape as well as twin crystal via either the single-chain nucleus or the two-chain nucleus. The folding conformation energies for the folds in a CPCFM are lower than those for conventional adjacent (110) folds. The configuration and conformation mentioned above, together with other evidences, discussed in part 2 of this series and an earlier communication make the CPCFM an acceptable regular folding model.