Date of Award


Document Type


Degree Name

Master of Science (MS)


Materials Science and Engineering

Committee Chair/Advisor

Dr. Kimberly Weirich

Committee Member

Dr. Konstantin Kornev

Committee Member

Dr. Igor Luzinov


Complex fluids and heterogenous mixtures composed of multiple types of polymers are found throughout industrial and biological fluid systems. For example, extrusion based additive manufacturing systems pass dense mixtures of polymers through the extrusion heads to deposit composite polymeric materials. In cells, active and complex mixtures of biopolymers self-organize into assemblies that perform critical physiological functions.

Polymers in dense solutions undergo phase separation as a result of differences in physiochemical properties. A few examples of these properties include charge, structure, rigidity, and hydrophobicity. We observe the formation of polymer domains composed of rigid and a flexible biopolymer species that phase separate due to differences in rigidity when crowded to a quasi-2D layer. We map the morphology of the biopolymer domains in the phase separated polymer mixture as a function of composition using fluorescence microscopy.

When rigid filaments form a continuous phase, the more flexible biopolymers form isolated, spindle shaped domains that are aligned, suggesting that the continuous phase is nematic. In contrast, when the flexible filaments form the continuous phase, the rigid filaments form spindle-shaped domains without preferential orientation, suggesting that the more flexible polymer forms a predominantly isotropic phase. We observe the formation of a continuous phase through the coarsening of small domains. During this process, regions of one polymer can be trapped and form polymer filled defects in the continuous phase.

Our results have the potential to inform self-organized systems, such as active patterning in soft materials and inform theoretical models of phase separation in complex polymer mixtures.

Available for download on Saturday, May 31, 2025