Abstract
Switch-functionalized mambranes, the permeability of which can be controlled by triggers induced by light, heat, etc., have been developed. These mambranes were designed by combination of crown ethers which act as ion carriers with functional groups which accept a signal from the outside world. In photoresponsive crown ethers, the stability constants of crown ethers can be changed by the conformational change which is induced by the trans-cis photoisomerization of the azobenzene moiety. Thus, the ion permeability of the membrane containing these photoresponsive crown ethers is directly affected by photoirradiation. In thermo-controlled membranes, the ion permeability can be controlled by crystal-liquid crystal phase transition in polymer/liquid crystal/amphiphilic crown ethers ternary composite membranes. These systems serve as well-constructed models for stimulus-responsive systems ubiquitously seen in nature.
