Chapter 6: Effect of Temperature on Nonionic Polymer Adsorption on SiO2 in Aqueous Media

6.1. Goal The objective of the work described in this chapter was to determine if the adsorption of a hydrogen-bonding homopolymer on SiO2 could be enhanced by thermal manipulation of solvent quality above or near the cloud point. It was shown in Chapter 2 from the studies of Killman and Malmsten that insolubility alone will not drive polymer adsorption, when the polymer is well solvated. However, by approaching the cloud point of the solution, the favorable interactions between the solvent and polymer are eliminated or significantly reduced. It may then be possible to drive adsorption with decreased solubility, should the effect of polymer insolubility be stronger than the decrease in hydrogen-bonding between the polymer and the substrate, as the temperature is increased. Lowering the temperature will drive the soluble polymer chains back into solution. Given the slow kinetics of polymer desorption, no significant immediate desorption of polymer would be expected as the temperature is lowered. If adsorption is promoted, this approach could lead to a brushlike layer for a well designed copolymer stabilizer due to enhanced adsorption.