Actuation in crosslinked polymers via photoinduced stress relaxation

The photoinduced polymer actuation by relieving stress unevenly through the thickness of a chemically crosslinked, rubbery polymer upon light exposure was investigated. It was found that the sensitivity of this method to light was greater that previously developed photoinduced actuation techniques. Radicals were produced and the stress was relieved on the irradiated side by placing a stress throughout an optically thick sample and irradiating only one side of the sample. A light intensity gradient through the sample was produced by formulating the resin with an UV absorber. The effect of the light intensity on the stress relaxation rate was examined in transparent samples. The increased dependence on light intensity enhanced the stress gradient that can be achieved, increasing the amount of sample deformation. Such mechanisms increase the flexibility of the current systems, allowing for its use in several applications.