ABSTRACT
Functional polymers, which can react, adjust or modulate their physicochemical character,i.e., in most cases their water-solubility, in response to an external stimulus, are generally referred to as “smart materials” or, if they are water-swellable, as “intelligent gels” or “wetware”. The physical basis of this “smart” behavior is a fast and reversible change of the polymer microstructure from a hydrophilic to a more hydrophobic one, triggered by small changes in the environment. These microscopic changes result at the macroscopic level, for example, in the formation of a precipitate or in a change in the wettability of a surface to which the smart polymer is grafted. The changes are usually reversible and the system returns to its initial state when the stimulus is removed. The most commonly used environmental stimuli are temperature and pH, since the two variables are relatively easy to change. Other possible stimuli include electricity, ions, solvents, light and pressure. For biological processes, smart polymer systems, which respond to the presence of specific small molecules (such as glucose), are also highly useful.
