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Diffusion of semi‐flexible polyelectrolyte through nanochannels
Author(s) -
Gu Hongyan,
Faucher Santiago,
Zhu Shiping
Publication year - 2010
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.12106
Subject(s) - polyelectrolyte , diffusion , radius of gyration , chemistry , polymer , aqueous solution , thermodynamics , hydrodynamic radius , polystyrene , polymer chemistry , chemical physics , physics , copolymer , organic chemistry
The diffusion of sodium polystyrene sulfonate through polycarbonate nanochanels was studied in salt‐free dilute aqueous solution. A stronger molecular weight dependence of diffusion was observed compared to free diffusion in dilute solution. Scaling exponentials relating polymer size to diffusivity were between Flory's theory ( D eff ∝ N −0.6 ) and Rouse's model ( D eff ∝ N −1 ), revealing a crossover regime from 3‐D diffusion to 1‐D diffusion. Diffusion was less hindered for the polyelectrolyte ( D eff / D 0 ), than for a rigid sphere, when the polymer/channel size ratio exceeded 0.2. This is attributed to elongated chains with reduced frictional hindrance. Simulation of the confined diffusion based on an elongated cigar model gave D ∝ N −1 ${R_{\rm t}^{2/3}}$ while the experimental results agree with D ∝ N −0.94 ${R_{\rm t}^{ 2/3}}$ . For charged polyelectrolytes, the transition to 1‐D diffusion therefore begins before the polymer radius of gyration exceeds the channel size contrary to model assumptions. We attribute this to the charged nature of the polyelectrolytes causing extended chain conformations. © 2009 American Institute of Chemical Engineers AIChE J, 2010