The high free volume polymers show promising properties for targeted gas and vapour membrane separations. The nature of their inner structure (a combination of porous and non-porous material) is responsible for specific transport properties. In this work, we report equilibriumsorption data of linear C1-C4 alkanols and C5-C7 alkanes in amorphous glassy perfluoropolymer Teflon AF2400, a copolymer of 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole (87%) with tetrafluoroethylene (23%) [1] and in the polymer with intrinsic microporosity, PIM-1, prepared from5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane and tetrafluoroterephthalonitrile [2]. The vapour sorption experiments were performed using a sorption apparatus equipped with calibrated quartz (McBain's) spiral balances [3]. The equilibriumsorption of alkanol vapours in Teflon AF2400 shows curved isotherms, which become almost linear as the chain length of alkanols increases [4]. Such phenomenon can be explained by a certain form of molecular aggregation, known as clustering, and can be quantified via ENSIC model [5,6]. The ENSIC model involves two key affinity-parameters, expressing relations between the non-polymeric species and polymer segment or previously sorbed solvent molecule, respectively. Conversely, the equilibrium sorption of vapours of alkanes in Teflon AF 2400 shows the Sshape type of isotherms, which can be well represented using the GAB model [6,7], whereas a rough approximation can be also obtained using the BET model [6]. Both GAB and BET models imply surface adsorption of the sorbate on the surface. Sorption isotherms of vapours of alkanols and alkanes in PIM-1 showS-shaped character. The total sorption of all vapours in PIM-1 was approximately one order of magnitude higher than in the case of AF 2400. Equilibriumsorption of vapours of alkanols and alkanes in PIM-1 was well described with the GAB model, indicating most probably no significant difference in the sorption mechanism of alkanols and alkanes in this polymer. Figure 1 Sorption of methanol vapour in PIM-1 and Teflon AF 2400 at 25°C. The left axis corresponds to the sorption of methanol vapour in PIM-1, the right axis corresponds to the sorption in Teflon AF 2400. The solid curves represent the GAB model (PIM-1) and the ENSIC model (Teflon AF2400). Acknowledgements The work leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° NMP3-SL-2009-228631, project DoubleNanoMem. The authors are also thankful for financial support of the Ministry of Education, Sports and Youth MSM(Grant No. 6046137307) and Grant Agency of Czech Republic (Grants No. 104/09/1357 and 106/10/1194). References [1] J.C. Jansen, M. Macchione, E. Tocci, L. De Lorenzo, Y.P. Yampolskii, O. Sanfirova, V.P. Shantarovich, M. Heuchel, D. Hofmann, E. Drioli, Macromolecules 42 (2009) 7589-7604. [2] T. Emmler, K. Heinrich, D. Fritsch, P.M. Budd, N. Chaukura, D. Ehlers, K. Rätzke, F. Faupel, Macromolecules 43 (2010) 6075-6084.
Equilibrium sorption of vapours of alkanes and alkanols in high free volume polymers
Jansen;J C;Bernardo P;
2011
Abstract
The high free volume polymers show promising properties for targeted gas and vapour membrane separations. The nature of their inner structure (a combination of porous and non-porous material) is responsible for specific transport properties. In this work, we report equilibriumsorption data of linear C1-C4 alkanols and C5-C7 alkanes in amorphous glassy perfluoropolymer Teflon AF2400, a copolymer of 2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxole (87%) with tetrafluoroethylene (23%) [1] and in the polymer with intrinsic microporosity, PIM-1, prepared from5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisindane and tetrafluoroterephthalonitrile [2]. The vapour sorption experiments were performed using a sorption apparatus equipped with calibrated quartz (McBain's) spiral balances [3]. The equilibriumsorption of alkanol vapours in Teflon AF2400 shows curved isotherms, which become almost linear as the chain length of alkanols increases [4]. Such phenomenon can be explained by a certain form of molecular aggregation, known as clustering, and can be quantified via ENSIC model [5,6]. The ENSIC model involves two key affinity-parameters, expressing relations between the non-polymeric species and polymer segment or previously sorbed solvent molecule, respectively. Conversely, the equilibrium sorption of vapours of alkanes in Teflon AF 2400 shows the Sshape type of isotherms, which can be well represented using the GAB model [6,7], whereas a rough approximation can be also obtained using the BET model [6]. Both GAB and BET models imply surface adsorption of the sorbate on the surface. Sorption isotherms of vapours of alkanols and alkanes in PIM-1 showS-shaped character. The total sorption of all vapours in PIM-1 was approximately one order of magnitude higher than in the case of AF 2400. Equilibriumsorption of vapours of alkanols and alkanes in PIM-1 was well described with the GAB model, indicating most probably no significant difference in the sorption mechanism of alkanols and alkanes in this polymer. Figure 1 Sorption of methanol vapour in PIM-1 and Teflon AF 2400 at 25°C. The left axis corresponds to the sorption of methanol vapour in PIM-1, the right axis corresponds to the sorption in Teflon AF 2400. The solid curves represent the GAB model (PIM-1) and the ENSIC model (Teflon AF2400). Acknowledgements The work leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° NMP3-SL-2009-228631, project DoubleNanoMem. The authors are also thankful for financial support of the Ministry of Education, Sports and Youth MSM(Grant No. 6046137307) and Grant Agency of Czech Republic (Grants No. 104/09/1357 and 106/10/1194). References [1] J.C. Jansen, M. Macchione, E. Tocci, L. De Lorenzo, Y.P. Yampolskii, O. Sanfirova, V.P. Shantarovich, M. Heuchel, D. Hofmann, E. Drioli, Macromolecules 42 (2009) 7589-7604. [2] T. Emmler, K. Heinrich, D. Fritsch, P.M. Budd, N. Chaukura, D. Ehlers, K. Rätzke, F. Faupel, Macromolecules 43 (2010) 6075-6084.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
