Articulo
Microcanonical molecular dynamics simulation of the vitreous phase transition of poly(binaphthylphosphazene)
Fecha
2017Registro en:
1150357
WOS:000397835400011
Institución
Resumen
Properties of poly(binaphthoxyphosphazene)s were investigated employing molecular dynamics simulations in the original microcanonical ensemble. In particular we have applied our methodology to the case of isotactic poly-(2,2'-dioxy-1,1'-binaphthylphosphazene) (P-DBNP) in order to estimate the vitreous transition temperature T-g, the energy barrier Ajig, for beta-relaxation of the BNP unit and the thermodynamic entropy of the system. According to our results, the transition is consistent with the Adam-Gibbs model and the specific rotation of et and beta-relaxations, which varies significantly with the molecular weight M. Our results suggest a rapid interconversion between the different proportions of the chiral R and S repeating units (70% and 30%, respectively) of the non-isotactic copolymer below 523 K and a slow atropisomerization of the DBNP units above 523 K which, in agreement with recent predictions on glassy polymer matrices, becomes much faster as the temperature approaches T-g similar to 573 K. (C) 2017 Elsevier B.V. All rights reserved.