MOLECULAR-DYNAMICS SIMULATIONS OF A POLY(ETHYLENE OXIDE) SURFACE

Potentials developed earlier for crystalline and amorphous bulk PEO sy stems have been used for the MD simulation of a PEO surface model. The surface comprises the outer region of a 122 Angstrom-thick sheet of P EO in which the PEO, -(CH2-CH2-O)(n)- chains run obliquely across the cell, and are terminated by C2H5 ethyl groups. The atoms on one side o f the sheet are tethered to facilitate a satisfactory Ewald summation. The sheet expands from its 'crystalline' width of 122 Angstrom to 128 Angstrom in the simulated model. Simulations were performed at three temperatures: 300 K, 400 K and 500 K. Different behaviour in the surfa ce layer was found compared to that in the bulk. The structural and dy namical properties of the surface were analyzed at each temperature. ( C) 1997 Elsevier Science Ltd.