It is shown that the condensation of the polyelectrolyte around the macroion shows a first order phase transition from a dense to a dilute concentration of monomers. The width of the condensed region increases with stronger screening or with smaller macro-ion charges. For small macro-ion charge, or when the Coulomb interactions are strongly screened, no complexation between the polyelectrolyte and the macro-ion happens. Additionally, long polyelectrolyte protrudes both tails and loops from the macroion. This is quite different from the case of large macroions where only tails appear. Our results can be used to explain various experimental trends. | Communications in Physics, Vol. 26, No. 3 (2016), pp. 287-295 DOI: SCREENING OF A SMALL SPHERICAL MACROION BY OPPOSITELY CHARGED FLEXIBLE POLYELECTROLYTE VU VAN QUYEN1 , VU THI HAI YEN2 AND NGUYEN THE TOAN1,3,† 1 VNU Key Laboratory Multiscale Simulation of Complex Systems, VNU University of Science, 334 Nguyen Trai Street, Thanh Xuan, Hanoi, Vietnam. 2 Faculty of Physics, VNU University of Science, 334 Nguyen Trai Street Thanh Xuan, Hanoi, Vietnam. 3 School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, Georgia 30332-0430, USA † E-mail: toannt@ Received 26 November 2016 Accepted for publication 31 December 2016 Abstract. Electrostatic interactions play important roles in the assembly, the structure and the functions of many biological as well as soft matter systems. In the presence of a macro-ion in aqueous solution, oppositely charged molecules mobilize around it to screen out its electrostatic potential. In this paper, we focus on screening of small macroion by a flexible polyelectrolyte using Monte−Carlo simulation. It is shown that the condensation of the polyelectrolyte around the macroion shows a first order phase transition from a dense to a dilute concentration of monomers. The width of the condensed region increases with stronger screening or with smaller macro-ion charges. For small macro-ion charge, or when the Coulomb interactions are strongly screened, no complexation between the polyelectrolyte and the macro-ion happens. Additionally, long polyelectrolyte protrudes both tails and loops from the macroion. This is quite different from the case of large macroions where only tails appear. Our results can be used to explain various experimental trends. Keywords: polyelectrolyte, macroion complexation, flexible polymer, electrostatic screening. Classification numbers: , . c 2016 Vietnam Academy of Science and Technology 288 SCREENING OF A SMALL CHARGED SPHERICAL .
