Authors: L. Giraud, S. Giasson
Affilation: Universty of Montreal, Canada
Pages: 224 - 225
Keywords: pH sensitive nanoparticles, adhesion, friction, surface propeties, polymer conformation, amino-functionalized monolayers
The unique property of polymers responding to external stimuli has made this class of smart materials very promising for various applications. A particular approach that has been widely used over the past decades is the chemical anchoring of end-functionalized linear polymers to substrates. The use of polyelectrolyte (PE) brushes as lubricants in aqueous systems has been proposed for their remarkable lubricating properties. Even after numerous studies of various PE-bearing surfaces in aqueous media, the precise way in which the polymer conformation and ionization control the resulting surface properties is still debated. To attempt better understanding of the underlying mechanism, we investigated the behavior of supported core/shell polystyrene (PS)/polyacrylic acid (PAA) nanoparticles (NPs). These NPs made of a cross-linked PAA shell are weakly charged that can undergo changes in surface properties. NPs were covalently attached onto an amino-functionalized monolayer also covalently attached on mica substrates. Normal and lateral forces measured between these supported NPs as a function of pH will be compared with different classes of solvated polymer-bearing surfaces in order to elucidate the role of the conformation, elasticity and electrostatic interaction of the polymer chains in controlling friction and adhesion between surfaces in aqueous media.