Molecular simulation of polymeric networks and gels: phase behavior and swelling

Polymer gels are commonly used in industrial, analytical, and domestic appl ications; their uses are likely to continue expanding as gels with novel ch emical and structural characteristics are developed. These applications oft en rely on the precise control of the adsorption behavior of a gel. Develop ment of useful gels, however, has been hampered by a lack of molecular-leve l understanding of the physics underlying phase transitions in such materia ls. In this report, we review recent molecular simulation work related to t he study of fundamental aspects of network elasticity and of phase transiti ons in polymeric gels. In particular, simulations of simplified (coarse-gra ined) molecular models are described which provide insights into the genera l behavior of gels, as opposed to studies concerned with the properties of specific materials. Methodological aspects unique to the simulation of diff erent properties of polymeric gels are emphasized. We also pay special atte ntion to the role of entropic factors (such as network topology, backbone s tiffness,, chain length asymmetry), over that of energetic interactions (su ch as hydrofobic interactions or ionic forces) on the onset and characteris tics of phase transitions in gels. In spite of the important advances made over the fast years in methodology and computer hardware, many challenges r emain if phase transitions for more realistic gel models are to be simulate d. (C) 1999 Elsevier Science B.V. All rights reserved.