Some polymeric systems are rather abruptly changing their properties due to external influences. These systems are addressed as switchable. Besides simple tasks, such systems can also perform rather complicated challenges, e.g., in molecular electronics, which is an emerging and rapidly developing field (1–4). Types of switchable devices are summarized in Table 14.1.
|Energy based||Chemical based|
|Magnetic field (8)||pH|
|Electric field (9)||Ionic strength|
|Temperature||Chemicals and Biochemicals (11)|
There are two major mechanisms for switching a device by a biomolecule (5):
Many polymers exhibit an ability to transition, however, Only a few show sharp transitions at moderate temperatures. These include poly(N-isopropyl acrylamide), poly(N,N-diethyl acrylamide), and poly(N-isopropyl acrylamide-co-2-carboxyisopropyl acrylamide) (5).
Electrodes modified with different signal-responsive materials have been designed as switchable electrochemical interfaces. These respond to a variety of physical an chemical signals.
Light-switchable electrodes are based on photoisomerizable ...