SWELLING MECHANISM IN SMART POLYMERS RESPONSIVE TO MECHANO-CHEMICAL STIMULI

Smart materials and smart structural systems are of paramount importance in the development of modern technological applications such as in bioengineering (tissue engineering, drug delivery, microscale surgery, …), packaging, data storage, molecular machines, smart sensors and actuators, etc. Smart polymers, often termed as responsive polymers, show physical or chemical changes in response to environmental stimuli of physical (ionic, temperature, radiation, light, mechanical stress, …), chemical (specific ions, pH, chemical agents, …), or biochemical (enzyme, substrates, ligands, …) nature; sometimes they could also respond to a combination of two or more triggering actions at the same time. In the present study the responsiveness of smart polymers to a chemical and mechanical stimuli at the same time is considered. In particular, being the chemical action typically carried by a solvent medium, the interplay of the fluid absorption mechanism and the chemical triggering one is accounted for. Moreover, in our study we focus also on the responsiveness capability of providing a detectable mechanical response at the mesoscopic scale, induced by a geometric change (typically a volume expansion) at the molecular scale. The mechanics of polymers undergoing swelling and showing responsiveness is investigated through a micromechanical model, subsequently implemented in a computational framework, for the prediction of the mechanical behavior of this class of active materials.