TITLE

Evaluation of the Gaussian Blob Model for Coarse-Graining Hydrodynamic Interactions in Isolated Polymer Molecules

AUTHOR(S)
Prabhakar, R.
PUB. DATE
July 2008
SOURCE
AIP Conference Proceedings;7/7/2008, Vol. 1027 Issue 1, p309
SOURCE TYPE
Conference Proceeding
DOC. TYPE
Article
ABSTRACT
Hydrodynamic interactions (HI) are important in a variety of systems such as colloidal suspensions and polymer solutions, both near and well beyond equilibrium. Detailed particulate simulations are increasingly an important tool in exploring the behaviour of such systems. An accurate method for coarse-graining long-range HI is desirable for designing efficient simulations, particularly when no obvious spatial symmetries can be exploited, as in the case of isolated flexible polymer molecules in solution. A recent model [Prabhakar et al. Phys. Rev. E, 76:011809 (2007)] proposed coarse-graining HI in a dilute polymer solution by representing a macromolecule as a chain of axisymmetric ellipsoidal Gaussian density fields, whose instantaneous dimensions are derived from their end-to-end stretch and orientation by invoking the assumption of local equilibrium. In this “Gaussian Blob” (GB) model, an expression was derived for the tensor describing HI between any pair of blobs. By combining the resulting mobility matrix with entropic spring force laws also based on the local equilibrium assumption, the GB model provides an alternative to the conventional bead-spring chain model with Rotne-Prager-Yamakawa HI. The advantage of the new model is that it has no free parameters, and all model parameters are uniquely related back to the polymer contour length, the Kuhn step length and the hydrodynamic diameter of the polymer contour. Preliminary simulations indicated that the GB model achieved a considerable reduction in the variation of predictions with respect to the number of blobs N chosen to represent the chain in comparison with the conventional bead spring model, irrespective of whether chains are stretched, or coiled near equilibrium. In this talk, I present more detailed results to confirm the practical viability of the coarse-grained HI used in the GB model. Firstly, the universal viscoelastic features predicted by both the GB and conventional models are identical, in the linear response regime, in strong extensional flows, and during relaxation after being initially expanded. In addition, the much smaller variation with N observed with the GB model means that a single low choice of N∼5 can be used to perform reliable and computationally efficient simulations under a variety of conditions without the necessity for adjusting parameters. I also discuss applications of this model to model more complex structures and illustrate its use with simulations for linear and nonlinear rheological properties of rod-coil block co-polymers.
ACCESSION #
33183894

 

Related Articles

  • Gaussian approximation for Rouse chains with hydrodynamic interaction. Öttinger, Hans Christian // Journal of Chemical Physics;1/1/1989, Vol. 90 Issue 1, p463 

    A new approximate method for treating hydrodynamic interactions in a bead–spring model for dilute polymer solutions is developed. This method, which is based on the assumption that the configurational distribution function is Gaussian, accounts for fluctuations in the hydrodynamic...

  • Linear viscoelasticity of dense colloidal suspensions. Cichocki, B.; Felderhof, B. U. // Journal of Chemical Physics;11/1/1994, Vol. 101 Issue 9, p7850 

    In earlier exact calculations of the linear viscoelastic behavior of semidilute suspensions of hard spheres we have shown that hydrodynamic interactions have a significant influence on the frequency dependence of the dynamic shear viscosity. Scaling with the mean relaxation time is not...

  • Viscoelastic relaxation of segment orientation in dilute polymer solutions. Perico, Angelo; Guenza, Marina // Journal of Chemical Physics;9/15/1985, Vol. 83 Issue 6, p3103 

    Time autocorrelation and memory functions for segment orientation are derived for a general diffusion model of a linear polymer chain in solution. Exact analytical results for the orientation and alignment memories P1(t), P2(t) (averages of the first and second order Legendre polynomial of the...

  • Viscoelastic effects in early stage phase separation in polymeric systems. Onuki, Akira; Taniguchi, Takashi // Journal of Chemical Physics;4/1/1997, Vol. 106 Issue 13, p5761 

    Examines the effect of viscoelasticity on early stage spinodal decomposition in polymer solutions and blends when fluctuations of the stress and the composition are coupled in dynamics. Proposed systematic experiments; Formation of sponge-like network structures composed of thin polymer-rich...

  • Viscoelastic relaxation of segment orientation in dilute polymer solutions. II. Stiffness dependence of fluorescence depolarization. Perico, Angelo; Guenza, Marina // Journal of Chemical Physics;1/1/1986, Vol. 84 Issue 1, p510 

    The memory functions for the orientation of a segment in any position on a linear chain are calculated for a diffusion Gaussian model in the optimized Rouse–Zimm approximation for semiflexible polymer models. The crossover from flexible to rod chains is described and expectations for...

  • Polymer solution viscoelasticity from two-parameter temporal scaling. Phillies, George D.J. // Journal of Chemical Physics;3/22/1999, Vol. 110 Issue 12, p5989 

    Proposes a novel approach for computing aspects of the loss modulus of a polymer solution. Polymer solution viscoelasticity; Comparison with representative results from the published literature.

  • Viscoelasticity of Dental Tissue Conditioners during the Sol-gel Transition. Murata, H.; Chimori, H.; Hamada, T.; McCabe, J. F. // Journal of Dental Research;Apr2005, Vol. 84 Issue 4, p376 

    Formation of tissue conditioners is a process of polymer chain entanglements. This study evaluated the influence of composition and structure on dynamic viscoelasticity of concentrated polymer solutions based on poly(ethyl methacrylate) (PEMA) used as tissue conditioners through the sol-gel...

  • Shear-induced structure in polymer blends with viscoelastic asymmetry. Hobbie, E. K.; Jeon, H. S.; Wang, H.; Kim, H.; Stout, D. J.; Han, C. C. // Journal of Chemical Physics;10/1/2002, Vol. 117 Issue 13, p6350 

    Light scattering and optical microscopy have been used to measure the morphology as a function of shear rate and composition in polymer blends with viscoelastic asymmetry in the melt components. The blends studied are immiscible mixtures of low-vinyl polybutadiene (PB) and high-vinyl...

  • Hydrodynamic screening and particle dynamics in porous media, semidilute polymer solutions and polymer gels. Altenberger, Andrzej R.; Tirrell, Matthew; Dahler, John S. // Journal of Chemical Physics;5/1/1986, Vol. 84 Issue 9, p5122 

    The dynamics of particle interactions in porous media are studied using a newly formulated mean field theory. Statistical correlations in the gel network are analyzed in detail and found to have a crucial influence on the results. Self-diffusion and mutual diffusion coefficients of Brownian...

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics