ABSTRACT
It has been known for many decades that cross-linked polymer gels are capable of responding mechanically to chemical stimuli. Starting with the early work of Kuhn et al. [1], numerous investigators have investigated the ability of polyelectrolyte gels to convert chemical changes, such as changes in pH or ionic environment, into mechanical work [26]. It has also been noticed that changes in swelling of gels can be exploited to modulate the transport of solutes, and this has given rise to numerous studies of chemically responsive drug-delivery systems [7-9].
