EFFICIENT SAMPLING OF SOLVENT-FREE ENERGIES IN POLYMERS

Solvent excess chemical potentials in amorphous polymers were calculat ed by means of molecular dynamics simulations using two different meth ods, the thermodynamic integration method and an extended ensemble met hod, during which the coupling of a test particle with the rest of the system is continuously changing. The latter method was found to probe the simulation box very efficiently whereas, in the thermodynamic int egration, only limited regions of the box were sampled. Excess free en ergies of chloroform in swollen polydimethylsiloxane were found to dec rease with increasing solvent swelling in qualitative agreement with e xperiment. (C) 1998 American Institute of Physics. [S0021-9606(98)5104 1-0].