Mechanical Characterization of Synthetic Vascular Materials

Biological materials in living organisms are furnished with a vascular system for the transportation and supply of necessary biochemical components. Many critical functions are supported by these vascular systems, including the maintenance of homeostasis, growth, autoimmune responses, regeneration, and repair. Synthetic materials with vascular systems have been created via a number of fabrication techniques in order to mimic some of these functionalities. The direct ink writing technique has been used to create polymer matrix, vascularized materials with micron-scale channels capable of autonomic repair. Liquid healing agents are delivered via the vascular system to sites of damage, where they polymerize in the crack plane, forming an adhesive bond with the surrounding material and recovering the mechanical integrity of the material. Characterizing the mechanical integrity of these materials is critical to optimizing their strength and toughness. The spacing between vascular conduits and the presence of locally-placed particle reinforcement have been shown to affect the local strain concentrations measured in these materials. In this work we study the effect of vascular geometry and local microchannel reinforcement on the bulk properties of the vascular material. Dynamic mechanical analysis is conducted to evaluate the stiffness of various vascular designs, and single edge notch beam (SENB) fracture samples are used to quantify the effect on fracture toughness.