Polyelectrolyte Physics

Solutions of polyelectrolytes are Coulomb soups of charged strings and are ubiquitous in biological and synthetic systems. The coupling among long-ranged correlations, arising from electrostatic interactions and polymer-connectivity, results in many complex phenomena unknown in uncharged polymeric systems. Theoreticl methods, simulations (Monte Carlo and Brownian Dynamics), and experiments (static and dynamic light scattering, SAXS, WAXS, SANS, NMR, conductometry) are used to investigate the following issues.

Effective charge of an isolated polyelectrolyte and the nature of counterion distribution
Size of labelled chains and correlations of monomer density of polyelectrolytes in solutions
Dynamics and conductivity in polyelectrolyte solutions
Micellization of diblock polyelectrolytes
Phase diagrams
Equation of state of polyelectrolyte gels
Effects of semiflexibility on the above
Adsorption and pattern recognition

Our experimental systems include polystyrene sulfonate, polyhexadiene sulfonates, monodisperse DNA, microtubules, and FtsZ.

	Counterion distribution around a polyelectrolyte chain. click on the image to see animation
	Measured radius of gyration, correlation length, and estimated Debye length in semidilute polyelectrolyte solutions. click on the image to enlarge the figure
	Experimental demonstration of the Ising behavior near the coexistence curve in polyelectrolyte solutions. click on the image to enlarge the figure
	Role of semiflexibility in phase behavior. click on the image to enlarge the figure

Recent Publications

"Theory of counter-ion condensation on flexible polyelectrolytes: Adsorption mechanism"M. Muthukumar, JCP 120 (19): 9343-9350 (200 4)
"Polyelectrolyte solutions with added salt: A simulation study", S. Liu, K. Ghosh and M. Muthukumar, JCP 119 (3): 1813-1823 (2003).
"Polyelectrolyte chain dimensions and concentration fluctuations near phase boundaries",V.M. Prabhu, M. Muthukumar, G.D. Wignall, et al. JCP 119 (7): 4085-4098 (2003).
"Phase transitions in solutions of semiflexible polyelectrolytes", K. Ghosh, G. A. Carri and M. Muthukumar, J. Chem. Phys. 116, 5299-5307 (2002).
"Phase diagram of polyelectrolyte solutions: weak polymer effect", M. Muthukumar, Macromolecules 35, 9142-9145 (2002).
"Langevin dynamics simulation of flexible polyelectrolytes", S. Liu and M. Muthukumar, J. Chem. Phys. 116, 9975-9982 (2002).
"Monte Carlo studies of adsorption of a sequential polyelectrolyte to patterned surfaces", J. McNamara, C. Y. Kong and M. Muthukumar, J. Chem. Phys, 117, 5354-5360 (2002).
"Dimensions of polyelectrolyte chains and concentrationfluctuations in semidilute solutions of sodium-poly(styrene sulfonate) as measured by small-angle neutron scattering", V.M. Prabhu, M. Muthukumar, G.D. Wignall and Y.B. Melnichenko, Polymer, 42, 8935-8946 (2001).
"Scattering properties of a single semiflexible polyelectrolyte", K. Ghosh and M. Muthukumar, J. Polym. Sci., Part B: Polym. Phys. 39, 2644-2652 (2001).
"Polyelectrolyte Adsorption on Heterogeneously Charged Surfaces", M. Ellis, C.Y. Kong, and M. Muthukumar, J. Chem. Phys. 112, 8723-29 (2000) .
"Coupling between adsorption and the helix-coil transition", G.A. Carri and M. Muthukumar, Phys. Rev. Lett.82, 5405-5408 (1999).
"Monte Carlo study of adsorption of a polyelectrolyte onto charged surfaces", C.Y. Kong and M. Muthukumar, J. Chem. Phys. 109,1522 (1998).
"Dynamics of Polyelectrolyte Solutions, M. Muthukumar", J. Chem. Phys. 107, 2619 (1997).
"Double Screening in Polyelectrolyte Solutions: Limiting Laws and Crossover Formulas", M. Muthukumar, J. Chem. Phys. 105, 5183 (1996)
"Polyelectrolytes at Interfaces: Pattern Recognition", M. Muthukumar, in Interfacial Aspects of Multicomponent Polymer Materials, Ed. L. Sperling, D. Lohse, and T. Russell, American Chemical Society, 1997.
"Adsorption of a Polyelectrolyte Chain to a Charged Surface", M. Muthukumar, J. Chem. Phys., 86, 7320 (1987).