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Gebäck, Tobias
Publications (2 of 2) Show all publications
Erdtman, E., Gebäck, T. & Ahlström, P. (2012). Atomistic Modelling of Protein Superabsorbents. In: : . Paper presented at European Symposium on Applied Thermodynamics the ESAT 2012 Potsdam, Tyskland.
Open this publication in new window or tab >>Atomistic Modelling of Protein Superabsorbents
2012 (English)Conference paper, Poster (with or without abstract) (Other academic)
Keywords
Protein, Superabsorbents, Monte Carlo Simulation
National Category
Theoretical Chemistry Other Chemical Engineering
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-6876 (URN)2320/11664 (Local ID)2320/11664 (Archive number)2320/11664 (OAI)
Conference
European Symposium on Applied Thermodynamics the ESAT 2012 Potsdam, Tyskland
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2017-01-22Bibliographically approved
Ahlström, P., Gebäck, T., Johansson, E. & Bolton, K. (2010). Water absorption in polymers. Paper presented at 8th European Conference on Computational Chemistry, 25-25.8, Lund. Paper presented at 8th European Conference on Computational Chemistry, 25-25.8, Lund.
Open this publication in new window or tab >>Water absorption in polymers
2010 (English)Conference paper, Poster (with or without abstract) (Other academic)
Abstract [en]

In this work two different examples of water absorbtion in polymers are studied by Monte Carlo simulations. Both of them are of large technical and commercial impotance. The first example is the water absorption in polyethylene cables where the water absorption plays a crucial role in the degradation of the cable insulation and thus should be as low as possible. The second example is bio-based superabsorbents made from denatured protein where water absorption capability is the prime desired property. Methods Gibbs Ensemble Monte Carlo simulations [1] were used to study the hydration of polymers. All simulations are performed with two boxes, one of which is filled with water at the start of the simulation, whereas the other contains polymer molecules and possible ions. The polymer molecules are not allowed to swap boxes whereas the water molecules are allowed to do so thus constituting an osmotic Gibbs ensemble [2]. For the polyethylene a connectivity-altering algorithm was used whereas the protein molecules were simulated using a side-chain regrowth model in addition to traditional Monte Carlo moves. For the polyethylene, the TraPPE [3] force field was used and the protein molecules, the Amber force field [4] was used. Water was modelled using simple point charge models [5]. Electrostatic interactions are treated using Ewald summation methods. The protein molecules were of different amino acid compositions and in different conformations, e.g., β-turns and random coils obtained using the amorphous cell method[6]. Studies were made with different degrees of charging on, e.g., lysine side chains mimicking different ionization states. Results The studies of polyethylene revealed the importance of ions left from the polymerisation catalyst for the absorbtion of water and the concomitant degradation of polyethylene cable insulation. Also the absorption properties of the protein molecules is strongly related to the presence of charged groups and fully charged protein molecules absorb large amounts of water. However, neither native nor denatured protein molecules show superabsorbing properties (i.e. absorbing hundreds of times their own mass) as they show in experimental studies and the reasons for this discrepancy will be discussed. References 1. A.Z. Panagiotopoulos, Mol. Phys. 61, 813 (1987). 2. E. Johansson, K. Bolton, D.N. Theodorou, P. Ahlström, J. Chem. Phys., 126, 224902 (2007). 3. M.G. Martin, and J.I. Siepmann, J. Phys. Chem. B, 103, 4508-4517 (1999). 4. W.D. Cornell, P. Cieplak, C.I. Bayly, I.R. Gould, K.M. Merz Jr, D.M. Ferguson, D.C. Spellmeyer, T. Fox, J.W. Caldwell, P.A. Kollman (1995). J. Am. Chem. Soc. 117, 5179–5197. 5. H. J. C. Berendsen, J. P. M. Postma and W. F. van Gunsteren, in Intermolecular Forces, B. Pullman, ed. (Reidel, Dordrecht, 1981) p. 331; H. J. C. Berendsen, J. R. Grigera and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987). 6. D.N. Theodorou, U.W. Suter, Macromolecules, 18, 1467 (1985).

Keywords
Resursåtervinning, Computational modelling
National Category
Theoretical Chemistry Other Industrial Biotechnology
Identifiers
urn:nbn:se:hb:diva-6524 (URN)2320/7484 (Local ID)2320/7484 (Archive number)2320/7484 (OAI)
Conference
8th European Conference on Computational Chemistry, 25-25.8, Lund
Available from: 2015-12-22 Created: 2015-12-22
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