摘要 : Molecular dynamics simulation (NPT ensemble) has been used to obtain specific volume as a function of temperature for four polyphosphazenes. From these results, the volumetric glass transition temperature has been determined as th... 展开 Molecular dynamics simulation (NPT ensemble) has been used to obtain specific volume as a function of temperature for four polyphosphazenes. From these results, the volumetric glass transition temperature has been determined as the temperature marking the discontinuity in slope of the V-T simulation data. The molecular mechanics force field used in this study was COMPASS (Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies) which has been extensively parameterized and validated for phosphazenes in a previous communication. The polyphosphazenes include poly[bis(2,2,2-trifluoroethoxy)phosphazene] (PTFEP) and three isomers of poly(dibutoxyphosphazene)-poly[bis(n-butoxy)phosphazene] (PnBuP), poly[bis(iso-butoxy)phosphazene](PiBuP), and poly[bis(sec-butoxy)phosphazeve] (PsBuP). In all cases, there was reasonable agreement between experimental results and values of density and T_g obtained from the simulations. In the case of PnBuP, two different methods for amorphous cell building are compared to explore the relationship between the state of equilibration and the T_g obtained from simulation. 收起