Molecular Dynamics Simulation of Brushes Formed by Star Polyelectrolytes Under Theta Solvent Conditions
K Miliou and LN Gergidis and C Vlahos, JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, 55, 1110-1117 (2017).
Using molecular dynamics simulations, we have studied polyelectrolyte brushes formed by partially or fully charged star polymers tethered on a planar surface under theta solvent conditions. The diagram of states for salt-free solutions differs in the location of osmotic regime (OB) compared with the respective diagram reported by Borisov and Zhulina. In contrast, simulation results dictate that the OB regime appears for values of the ratio F/alpha(-1/2) l(B)(-1) much larger than unity, which is the threshold of counterion localization, with F denoting the branch functionality, a the charged units fraction and l(B) the Bjerrum length. The simulation results support that the brush height scaling laws H similar to alpha(2) l(B) F-1.049 S-3 s(-1) and H similar to alpha(0.302) F-0.23 S for the charged Pincus Brush (PB) and osmotic (OB) regimes, respectively, where S is the spacer length and s is the grafted area per star chain. The respective theoretical scaling laws are H similar to alpha(2) l(B) F-1.88 S-3 s(-1) and H similar to alpha(1/2) (FS)-S-0.44. (C) 2017 Wiley Periodicals, Inc.
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