Extension of the stimulus expansion model for photo‐thermo‐sensitive hydrogels

Abstract

AbstractThe stimulus expansion model uses the analogy of thermal expansion in order to model the mechanical swelling behavior of a polymer gel. In the current work, we present an approach to extend the stimulus expansion model for photo‐thermo‐sensitive hydrogels. We describe the swelling behavior by using the stimulus properties, in our case light, as input values and the volume change of the hydrogel as the result by physical coherences. Further, we consider the energy conversion from light into heat within the polymer gel, due to absorption by particles. This phenomenon is considered by an energy balance which depicts the energy input by applying Lambert‐Beer's law. for the absorption of light. By evaluating the energy balance, we can calculate the light dependent temperature increase of the thermo‐sensitive hydrogel. Afterwards, the hydrogel's swelling is modeled by using the thermal expansion analogy. This detailed description of the stimulus behavior allows to study a hydrogel composite without having specific experimental data for this certain combination, but for all the involved components. Furthermore, the time‐dependent stimulus behavior of the considered sample is shown. Based on this approach, the effect of light power variation, particle volume fraction variation and different ambient temperature is studied.