Introduction to Ionic Polymers, Ionic Gels, and Artificial Muscles
Roentgen (1880) appears to have been the first to make an electroactive polymer. He used a rubber band that could change its shape by being charged or discharged. Later, Sacerdote (1899) formulated the strain response to electric field activation in polymers. In 1925 Eguchi (1925) reported the discovery of a piezoelectric polymer that he called an electret. He found that when molten carnauba wax, rosin, and beeswax were solidified by cooling in the presence of a DC electric field, the resulting material was piezoelectric. Generally, electrical excitation is only one type of stimulator that can induce elastic deformation in polymers. Other activation mechanisms include chemical (Katchalsky, 1949; Kuhn et al., 1950; Steinberg et al., 1966; Shahinpoor, 1992, Shahinpoor et al., 1997a, 1997b; Otero et al., 1995), thermal (Kishi et al., 1993; Tobushi et al., 1992; Li et al., 1999), pneumatic (Shahinpoor et al., 2001), optical (van der Veen and Prins, 1971), and magnetic (Zrinyi et al., 1997).