title: Measurement of the electrostatic interaction between polyelectrolyte brush surfaces by optical tweezers.
abstract: We demonstrated an optical tweezers method to measure the electrostatic interaction between the strong polyelectrolyte brushes, poly(2-(methacryloyloxy)ethyltrimethylammonium chloride) (PMTAC), grafted on silica particles in aqueous media. The weak electrostatic interaction was successfully detected with a resolution of less than 0.1 μN m(-1). The apparent Debye length, including the charge distribution in the polymer brush and the surface potential, decreased as the salt concentration in the medium increased. The experimentally obtained surface charge density was much smaller than that estimated from the amount of polyelectrolyte on the surface. Furthermore, the dissociation of ionic groups was enhanced by decreasing the grafting density of the polyelectrolyte brush. The results suggest that the majority of chloride counterions was immobilized in the dense polyelectrolyte brush layer to neutralize the high charge density.
authors: Japan Science and Technology Agency (JST), ERATO, Takahara Soft Interfaces Project, and ‡Institute for Materials Chemistry and Engineering, CE80, Kyushu University , 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan.
authors: Daiki
authors: D
authors: Murakami
authors: Ai
authors: A
authors: Takenaka
authors: Motoyasu
authors: M
authors: Kobayashi
authors: Hiroshi
authors: H
authors: Jinnai
authors: Atsushi
authors: A
authors: Takahara