Journal of Chemical Physics, Vol.118, No.3, 1521-1532, 2003
Detailed atomistic Monte Carlo simulation of grafted polymer melts: II. Orientational order and nuclear magnetic resonance spectra
We present results on the profiles of the first- and second-rank bond-order parameters, [P-1(cos theta)] and [P-2(cos theta)], of the grafted polymer melts simulated in atomistic detail in Part I of this work, with the end-bridging Monte Carlo (EBMC) algorithm. The [P-1(cos theta)] and [P-2(cos theta)] profiles are discussed in terms of bond distance from the grafting surface and bond coordinate along chain contour. A methodology is also presented for calculating the deuterium (H-2) nuclear magnetic resonance (NMR) spectrum of the simulated grafted melts by analyzing the atomistic configurations accumulated in the course of the EBMC simulations. The calculation of the deuterium NMR spectrum is found to be very sensitive to the details of the profile of the second-rank bond-order parameter. For the systems simulated in the present work (melts of linear C-78 and C-156 polyethylene melts at grafting densities sigma ranging from 1.31 to 2.62 nm(-2)), calculated H-2 NMR splittings are on the order of a few kilohertz, in agreement with experimentally measured values through deuterium NMR spectroscopy. (C) 2003 American Institute of Physics.