Structural Change And Correlation Between Side Chains In Poly(4-Methyl-1-Pentene) Melt Via Molecular Dynamics Simulation

Poly(4-methyl-1-pentene) (P4MP1) is characterized by large side chains, and X-ray diffraction measurements on P4MP1 melts have revealed an abrupt change in the pressure dependence of the diffraction patterns in wavenumber space that indicated a pressure-induced liquid-liquid transition [A. Chiba et al., Phys. Rev. E 85, 021807 (2012)]. We perform a molecular dynamics simulation using a coarse-grained model to clarify the details of the microscopic structure of P4MP1 melts in real space. The side chains are sparsely distributed in a low-density melt, and as density increases, such an open-packed structure changes into a densely-packed structure, in which the branches of the side chains mesh with each other and the correlation between them increases.