Linking atomistic and mesoscale simulations of water-soluble polymers

Journal of the American Chemical Society

Volumn 125, Issue 24, 2003, Pages 7190-7191

  Noro, Massimo G ^a   Paul, Prem K C ^a   Warren, Patrick B ^a  

^a UNILEVER RESEARCH   (United Kingdom)

Author keywords

[No Author keywords available]

Indexed keywords

POLYMER; WATER;

ADSORPTION; AQUEOUS SOLUTION; ARTICLE; ATOMIC PARTICLE; ENERGY; MOLECULAR DYNAMICS; MOLECULAR MODEL; POLYMERIZATION; SIMULATION; STEADY STATE; STEREOCHEMISTRY; THERMODYNAMICS;

EID: 0038451348     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja0343914     Document Type: Article

References (21)

1. Case, F. H.; Honeycutt, D. J. Trends Polym. Sci. 1994, 2, 259.
2. Molyneaux, P. In Water: A Comprehensive Treatise; Franks, F., Ed.; Plenum Press: New York, 1975; Vol. 4.
3. Free-energy calculations using thermodynamic integration are computationally intensive, and in an aqueous system one must use either complex continuum models or accurate interaction potentials for water. Also, the free-energy changes may be many times smaller than the reference free energies, which consequently have to be determined with great precision. Many references exist; see, for example, ref 9 for details of this method.
4. Examples of mesoscale methods are self-consistent field (SCF) theory used here, dynamic density functional theory (DDFT) as used in the Mesodyn code, dissipative particle dynamics (DPD).
5. Discover is a simulation program of Accelrys Inc.: San Diego, CA.
6. (a) Sun, H. J. Phys. Chem. B 1998, 102, 7338-7364.
7. (b) The compass force-field shows good evidence that the most important structural features of the liquid state of water such as the oxygen-oxygen pair correlation function (Soper, A. K.; Bruni, F.; Ricci, M. A. J. Chem. Phys. 1997, 106, 247) are reproduced. Such requirements are stringent for our purposes, since the force-field has to be trusted in the calculation of free energies.
8. The simulations were run in the NVT protocol, at T = 298 K and V obtained from a well-equilibrated NPT simulation at zero pressure.
9. For a model silica surface, we have used a surface of quartz obtained from its crystal structure, appropriately terminated and satisfying both the stoichiometry of the material and charge neutrality requirements.
10. Frenkel, D.; Smit, B. Understanding Molecular Simulations; Academic Press: San Diego, 1996.
11. The fitting parameters, b and e, in eq 2 arise from the fact that the surface is not necessarily located at z = 0 (the model silica surface is nominally located at about z = 6 Å).
12. bulk → 0. Indeed such methods are often based on free energy models from which these quantities can be directly calculated.
13. Fleer, G. H.; Cohen Stuart, M. A.; Scheutijens, J. M. H. M.; Cosgrove, T.; Vincent, B. Polymers at Interfaces; Chapman and Hall: London, 1993.
14. Sevink, G. J. A.; Fraaije, J. G. E. M.; Huinink, H. P. Macromolecules 2002, 35, 1848-1859.
15. Groot, R. D.; Warren, P. B. J. Chem. Phys. 1997, 107, 4423-4435
16. While the SCF approach is expected to provide the desired molecular-mesoscale link, the numerical values of the mesoscale parameters obtained also depend on implicit details of the mesoscale model (i.e. there are no unique set of values for χ parameters). But, just as for the link to the atomistic PMF, these or other thermodynamic quantities can be chosen to bridge between different mesoscale models, for an example for DPD see ref 14.
17. The SCF code (ACOPEL) was generously provided by Frans Leermakers of Wagningen University.
18. Karlström, G. J. Chem. Phys. 1985, 89, 4962-4964.
19. See Malmsten, M.; Linse, P.; Cosgrove, T. Macromolecules 1992, 25, 2474-2481 and references therein.
20. Rubio, J.; Kitchener, J. A. J. Colloid Interface Sci. 1976, 57, 132-142.
21. Of course, PMF methods may not be so readily useful for matching nonequilibrium quantities such as transport coefficients or viscosities or diffusion coefficients.