ABSTRACT
Stimuli-responsive polymers attract an ever-growing interest for the design of “smart” surfaces or interfaces, where properties (surface energy (Yakushiji et al. 1998), adhesion (Jones et al. 2002), friction (Ikeuchi et al. 1996, Chang et al. 2007)) can be strongly altered upon application of an external stimulus, such as a change in temperature, light, pH, etc. (Luzinov et al. 2004, Gil and Hudson 2004, Cole et al. 2009). Among such smart systems, thermosensitive coatings generally exploit the properties of polymers that exhibit a lower critical solution temperature (LCST) when mixed with a solvent (Freeman and Rowlinson 1960). Below the LCST, polymer chains are in good solvent conditions and adopt a swollen coil conformation. As temperature is increased across the LCST, the solvent quality shifts from good to poor, and
macromolecules collapse into a dense globular state. Such a phase separation is commonly encountered in binary mixtures in which specific interactions (e.g., hydrogen bonding) exist between constituents (Hirschfelder et al. 1937, Goldstein 1984), as it is the case in aqueous solutions of poly(N-isopropylacrylamide) (PNIPAM), one of the most extensively studied thermosensitive systems (Schild 1992, Wu and Zhou 1995).
