The Adsorption of Partially Hydrolyzed Polyacrylamide at the solid/liquid interface

H. Haschke¹, M. Antognozzi¹, M. J. Miles¹, S. Sheppard²

1) H.H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, U.K.
2) Schlumberger Cambridge Research Ltd, High Cross, Madingley Road, Cambridge, CB3 0EL, U.K.

Partially hydrolyzed polyacrylamide (PHPA) of high molecular weight has been bound covalently to a dithio-bis(succinimidylundecanoate) self-assembled monolayer (DSU-SAM) on atomically flat gold in a controlled way. With this technique the physical and chemical adsorption forces were investigated under different conditions with atomic force microscopy (AFM) and transverse dynamic force microscopy (TDFM). In all experiments the PHPA molecules were bound to the tip by gold coating the cantilevers and glass-fiber probes for the AFM and TDFM experiment, respectively, followed by exposure to PHPA solution after DSU-SAM formation. The adsorption forces were obtained by measuring the forces exerted on the tip when the bond between the molecule and the tip ruptures in the force-distance curve taken in an aqueous environment. Chemical adsorption forces were examined on a gold-coated mica sample with a DSU-SAM and physical adsorption force experiments were performed with a mica sample. The forces obtained with the novel TDFM are in agreement with those obtained with the AFM.