Simulações computacionais de membranas de poli(uretano-ureia) aplicadas a separação de gases

• Autor(a) principal: Silva, Flávia Cristina Assis
• Data de Publicação: 2017
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/15829
• topic: molecular dynamics; moly (urethane-urea); membrane; gas separation; dinâmica molecular; poli(uretano-ureia); membranas; separação de gases; CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA::PROCESSOS INDUSTRIAIS DE ENGENHARIA QUIMICA

Polymer based membranes for gas capture and separation have been investigated as an alternative to conventional systems, mainly in processes applied in the petrochemical industry. Due to their versatility, poly(urethane) (PU) and poly(urethane-urea) (PUU) have been studied as good candidates to be applied on gas capture/separation. Molecular dynamics (MD) simulations not only give support to the experiment, but also can predict structural, dynamical and thermodynamic properties. In this work, we propose a new approach for the development of a classical model for polymers simulations, in which the force field is based on the derivation of intramolecular parameters using Antechamber and ACPYPE tools, and with charges parameters obtained by a statistical sampling of the polymer conformations followed by the quantum chemistry calculations in vacuum. This methodology has been used to generate the topology and subsequent validation by molecular dynamics simulations, using as reference the density and the structure of the pure PUU. The density average obtained in the simulations with a value of 1.06 g.cm-³ agrees with data from the literature (1 - 1.2 g.cm-³ - Amani, 2014). We applied the developed model to study the gas separation (CO2 and CH4) by PUU membranes. Structural, dynamical and thermodynamic properties in the NpT ensemble were calculated, with high affinity of the membrane for CO2 than CH4. Structural calculation by the radial distribution function (RDF) allowed the characterization of microphase separation. The polymer-gas and polymer-polymer interactions revealed that there is preferential interaction of the CO2 with the rigid segment of polymer unlike the methane gas, which promotes a slight separation of the polymer chains. The model developed for PUU proved to be satisfactory to represent the studied systems and promising for future works involving polymer membrane simulation