Thermo-responsive diblock and triblock cationic copolymers at the silica/aqueous interface: A QCM-D and AFM study

Saeed Zajforoushan Moghaddam; Kaizheng Zhu; Bo Nyström; Esben Thormann

doi:10.1016/j.jcis.2017.06.044

Thermo-responsive diblock and triblock cationic copolymers at the silica/aqueous interface: A QCM-D and AFM study

J Colloid Interface Sci. 2017 Nov 1:505:546-555. doi: 10.1016/j.jcis.2017.06.044. Epub 2017 Jun 15.

Authors

Saeed Zajforoushan Moghaddam¹, Kaizheng Zhu², Bo Nyström², Esben Thormann³

Affiliations

¹ Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
² Department of Chemistry, University of Oslo, Blindern, P.O. Box 1033, Blindern, N-0315 Oslo, Norway, Norway.
³ Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark. Electronic address: esth@kemi.dtu.dk.

PMID: 28646758
DOI: 10.1016/j.jcis.2017.06.044

Abstract

The properties of synthesized diblock poly(N-isopropylacrylamide)-poly((3-acrylamidopropyl)trimethylammonium chloride) and triblock methoxy-poly(ethylene glycol)-poly(N-isopropylacrylamide)-poly((3-acrylamidopropyl)trimethylammonium chloride) cationic copolymers at the silica/aqueous interface are investigated using quartz crystal microbalance with dissipation monitoring (QCM-D) and atomic force microscopy (AFM). Moreover, dynamic light scattering is employed to assess the copolymers in terms of the hydrodynamic size and interchain aggregation. Although viscoelastic Voigt modeling of the QCM-D data suggests a comparable layer thickness for the copolymers on the silica surface, the AFM imaging and colloidal probe measurements reveal significant differences in surface coverage and thickness of the layers, which are discussed and compared with respect to the stabilization effect by the hydrophilic poly(ethylene glycol) block.

Keywords: Atomic force microscopy; Cationic copolymer; Dynamic light scattering; Poly(N-isopropylacrylamide); Poly(ethylene glycol); Quartz crystal microbalance with dissipation.