Rapid actuation of thermo-responsive polymers is desirable for many applications including soft robotics and medical devices. Shape recovery rates in thermo-responsive shape memory polymers (SMP) are governed by extrinsic diffusion length scales and intrinsic material properties including the thermal conductivity of bulk polymers and the nature of the temperature-dependent modulus change during phase transitions. The sharpness of the glass transition is a strong function of the molecular heterogeneity of the SMP. Strategies to maximize the rate of shape recovery in thermo-responsive SMP could improve intrinsic properties by increasing the bulk thermal conductivity and minimizing molecular heterogeneity. Extrinsic properties could be improved by choosing form factors that minimize the characteristic length scale for thermal diffusion. Shape memory actuators with embedded vascular structures can be fabricated using additive manufacturing techniques such as 3D printing. Here, we present the shape recovery kinetics in 3D-printed vascularized thermoplastic structures. Experimental and modeled shape recovery rates are compared to validate the utility of finite element modeling (FEM) to predict shape recovery rates. Theoretical and experimental time scales for shape recovery are in close agreement. This framework can predict the intrinsic physical property of SMP that limits the actuation rate. Taken together, this analysis can provide forward guidance when designing next-generation SMP with accelerated shape memory kinetics.
