title: Periodic swelling and collapse of polyelectrolyte brushes driven by chemical oscillation.
abstract: Poly(acrylic acid) (PAA) chains exhibit conformational change in response to pH, whereas bromate-sulfite-ferrocyanide (BSF) solution shows pH oscillation between 3.2 and 6.6. By use of quartz crystal microbalance with dissipation (QCM-D), we have investigated the pH induced conformational change of PAA brushes under a continuous flow of BSF solution in real time. The changes in frequency and dissipation clearly indicate the periodic swelling and collapse of brushes with pH oscillation. The changes in thickness, viscosity, and elastic modulus further indicate the oscillation of the interface.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei, China.
authors.forename: Guangming
authors.initials: G
authors.lastname: Liu
authors.forename: Guangzhao
authors.initials: G
authors.lastname: Zhang
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D001672:Biocompatible Materials / Q000737:chemistry; D002627:Chemistry, Physical / Q000379:methods; D004573:Electrolytes; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D008956:Models, Chemical; D008968:Molecular Conformation; D009991:Oscillometry; D011108:Polymers / Q000737:chemistry; D011791:Quartz; D013997:Time Factors; D014783:Viscosity; D014965:X-Rays
chemical_list: D000180:Acrylic Resins; D001672:Biocompatible Materials; D004573:Electrolytes; D011108:Polymers; D011791:Quartz; C006903:carbopol 940