Self-patterned growth of branched structures in non-curing and in curable structures via electro-hydrodynamic hele-shaw flow

Current research aims to find effective means of creating biomimetic vascular systems for polymeric composite materials. One method for autonomic growth of branching structures is explored in this thesis. Motivation is taken from electrical treeing and viscous fingering phenomena. Applying these basic principles, Saffman-Taylor instability is combined with an applied electrical potential in order to grow and control branching patterns in a curable polymeric system. The goal is to create a finely and complexly branched channel in a variety of matrix media. Increasing the viscosity ratio between the matrix and injection fluid increases the degree of branching and decreases droplet formation from the structure. Adding surfactant to a silicone oil system works to decrease the interfacial tension between these fluids and decreases droplet formation at the expense of some degree of branching. Increasing the voltage applied to the system increases branching, although also increases the amount of droplets. Flow rate must be finely tuned in order to avoid pooling in the channels. These principles hold true in a silicone oil and water system, and are similarly expressed in a curable pre-polymer matrix system. Successful cure of a finely branched system was achieved guided by an understanding of appropriate dimensionless groups describing the relative importance of physical forces. The viability of structures prepared in this way was demonstrated by successfully filling and flowing material through all length scales of branches.M.S., Chemical Engineering -- Drexel University, 200