Rigid polymer membranes are recently regarded as a state of the art materials for gas separation processes, due to their high permeability and selectivity [1-3]. However, despite extensive experimental studies, the relationship between structure and transport properties such as diffusivity and solubility is still in dispute. There are some empirically-accepted factors affecting diffusivity such as fractional free volume, interchain spacing, rigidity, etc [4, 5]. Considering that those parameters are various indirect ways to describe a free volume morphology, it is very important to characterize the exact amount, shape and distribution of free volume, which can resultantly improve our knowledge of the structure-transport relationship. In this study, we analyzed the free volume morphology of rigid polymers using molecular dynamics (MD) simulation, where hydroxy-containing polyimides (HPIs) and thermally rearranged polybenzoxazoles (TR-PBOs) were adopted as rigid polymer candidates. TR-PBO has high permeability that surpass the limits of conventional polymers, which is prepared from HPIs by thermal rearrangement reaction in the solid state structure [2]. Furthermore, mean square displacement calculation for diffusivity and GCMC simulation for solubility were performed with each 3D model. Comparing both results, we will correlate the free volume morphology and diffusivity/solubility, which can suggest the effective polymer structure for high gas transport performance. [1] M.D. Guiver, Y.M. Lee, Science, 339, 284 (2013). [2] H.B. Park, C.H. Jung, Y.M. Lee, A.J. Hill, S.J. Pas, S.T. Mudie, E. Van Wagner, B.D. Freeman, D.J. Cookson, Science, 318, 254 (2007). [3] M. Carta, R. Malpass-Evans, M. Croad, Y. Rogan, J.C. Jansen, P.Bernardo, F. Bazzarelli, N.B. McKeown, Science, 339, 303 (2013). [4] B.D. Freeman, Macromolecules, 32, 375 (1999). [5] S. Matteucci, Y. Yampolskii, B.D. Freeman, I. Pinnau, in Materials Science of Membranes for Gas and Vapor Separation, p.1, Y. Yampolskii, I. Pinnau, B.D. Freeman, Ed. (John Wiley & Sons, Ltd, Chichester, UK, 2006).
Effect of structural properties on the gas transport in rigid polymers
Park Chi Hoon;Tocci Elena;Drioli Enrico
2013
Abstract
Rigid polymer membranes are recently regarded as a state of the art materials for gas separation processes, due to their high permeability and selectivity [1-3]. However, despite extensive experimental studies, the relationship between structure and transport properties such as diffusivity and solubility is still in dispute. There are some empirically-accepted factors affecting diffusivity such as fractional free volume, interchain spacing, rigidity, etc [4, 5]. Considering that those parameters are various indirect ways to describe a free volume morphology, it is very important to characterize the exact amount, shape and distribution of free volume, which can resultantly improve our knowledge of the structure-transport relationship. In this study, we analyzed the free volume morphology of rigid polymers using molecular dynamics (MD) simulation, where hydroxy-containing polyimides (HPIs) and thermally rearranged polybenzoxazoles (TR-PBOs) were adopted as rigid polymer candidates. TR-PBO has high permeability that surpass the limits of conventional polymers, which is prepared from HPIs by thermal rearrangement reaction in the solid state structure [2]. Furthermore, mean square displacement calculation for diffusivity and GCMC simulation for solubility were performed with each 3D model. Comparing both results, we will correlate the free volume morphology and diffusivity/solubility, which can suggest the effective polymer structure for high gas transport performance. [1] M.D. Guiver, Y.M. Lee, Science, 339, 284 (2013). [2] H.B. Park, C.H. Jung, Y.M. Lee, A.J. Hill, S.J. Pas, S.T. Mudie, E. Van Wagner, B.D. Freeman, D.J. Cookson, Science, 318, 254 (2007). [3] M. Carta, R. Malpass-Evans, M. Croad, Y. Rogan, J.C. Jansen, P.Bernardo, F. Bazzarelli, N.B. McKeown, Science, 339, 303 (2013). [4] B.D. Freeman, Macromolecules, 32, 375 (1999). [5] S. Matteucci, Y. Yampolskii, B.D. Freeman, I. Pinnau, in Materials Science of Membranes for Gas and Vapor Separation, p.1, Y. Yampolskii, I. Pinnau, B.D. Freeman, Ed. (John Wiley & Sons, Ltd, Chichester, UK, 2006).I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
