Limiting electrophoretic mobility of a highly charged soft particle in an electrolyte solution: Solidification effect

作者：Ohshima Hiroyuki^*

来源：Journal of Colloid and Interface Science, 2010, 349(2): 641-644.

DOI：10.1016/j.jcis.2010.05.094

• Soft particle
• Limiting electrophoretic mobility
• Donnan potential
• Solidification effect

It is known that the electrophoretic mobility of a spherical rigid particle in an electrolyte solution with large kappa a (where kappa = Debye-Hilckel parameter and a = particle radius) and large Dukhin number (Du >> 1) tends to a nonzero constant value in the limit of high zeta potentials. A highly charged liquid drop exhibits the same limiting mobility value. That is, a liquid drop behaves as if it were a rigid particle (the solidification effect). In the present paper we derive the corresponding mobility expression for a highly charged spherical soft particle (i.e., a polyelectrolyte-coated particle) consisting of the particle core of radius a covered with an ion-penetrable surface layer of thickness d in a symmetrical electrolyte solution of valence z. It is shown that for kappa a >> and kappa d >> 1, the magnitude of the scaled limiting mobility mu((infinity)) is given by vertical bar mu((infinity))vertical bar = 2 epsilon(r)epsilon(0)kT/3 eta ze . (1 + a(3)/2b(3)) . 2 In 2, where epsilon(r) is the relative permittivity of the electrolyte solution, epsilon(0) is the permittivity of a vacuum, e is the elementary electric charge, and kT is the thermal energy. When a approximate to b, the obtained limiting mobility expression tends to the result for a rigid sphere. That is, the solidification effect is observed also for a soft particle.

• 出版日期2010-9-15