Several types of photo-responsive polymers have been developed over the past 10 years. However, current limitations (such as irreversibility, inadequate physical changes, and high expense) have prevented their widespread use. Bend Research proposes to pursue a new class of photo-responsive polymers for use in a variety of applications (e.g., optical memory devices, absorbants, switches in robotic systems, and coatings for pharmaceuticals and other active ingredients). Given Phase I limitations, we will focus this work on controlled-release applications. Our goal is to have these polymers provide 1) reversible (on/off) release of the active ingredient; 2) pulsatile or sustained delivery; 3) controllable release kinetics, independent of the triggering mechanism; and 4) efficient use of many different active ingredients at high concentrations. The proposed technology uses azobenzene compounds as a "switch" to cause reversible photo-induced changes in the polymer. When exposed to ultraviolet light, functional groups on an azobenzene compound and an agent compound cause changes in the physical properties of the polymer. The polymer properties return to their original values when not exposed to ultraviolet light. The proposed use of azobenzene differs from previous development efforts in that it does not rely solely on the isomerization of the azobenzene compounds as the conformational changes in the polymer.
