Molecular Modelling of Polyelectrolytes at Clay Surfaces
Mark Warne (previous student, left the group in 2000)
Kaolin, more commonly known as China Clay, is used extensively in the paper and ceramics industry. When kaolin is used as a paper coating pigment the sizes and shapes of the constituent clay particles can be of great importance. For example the whiteness, opacity and printing properties of a sheet of paper are all influenced by the shapes and sizes of the kaolin particles. These geometric factors also affect the rheological properties of suspensions of china clay in water, which are particularly important when the paper is coated on high speed machines running at over 1000 metres per minute.
The way in which the kaolin is dispersed in a suspension also influences pigment properties. In industrial processes the degree of dispersion exhibited by the clay particles is controlled by adsorbing low molecules weight (~1500 g / mol) poly(acrylic acid) onto the clay surface and by varying the pH and salt content within the suspension. Varying any of these constituents and parameters by even a small amount can significantly change the suspensions behaviour. By performing computer simulations a better insight into the molecular interactions which influence such properties may be obtained.
Simulation approaches implemented are molecular mechanics and molecular dynamics. Simulation software used includes GULP (Imperial College), DLPOLY (CCP5) and Cerius2 (MSI).
Links
Simulation gallery Contains snapshots and animations of the simulations carried out.
Publications List
Clifton, B. J., Cosgrove, T., Warne, M. R. Calculation of Silberberg's Polymer Segmental Adsorption Energy by a Free Space Molecular Modeling Technique, Langmuir, 1999; 15(25); 8659-8667
Clifton, B. J., Cosgrove, T., Warne, M. R. Methods for calculating solvent enthalpy of vapourisation values by a molecular modelling technique-effect of charge and method, Colloids and Surfaces A-Physicochemical and Engineering Aspects; 2000, 164(2-3), 163-173
Shar, J. A., Cosgrove, T., Obey, T. M., Warne, M. R., Wedlock, D. J. Adsorption Studies of Diblock Copolymers at the Cyclohexane/Carbon Black Interface, Langmuir; 1999; 15(22); 7688-7694
Spenley, N.A., Warne, M.R., General Discussion, Faraday Discussions, 1999, 112,167
This project is funded by English China Clays plc, part of the Imerys Group
