LIQUID BRIDGE TO STABLE FIBRE: POLYMER ENTANGLEMENT DRIVES FIBRE FORMATION FROM HIGHLY CONCENTRATED DEXTRAN SOLUTIONS

Abstract

Liquid bridges have been studied for over 200 years, due to their countless natural and industrial occurrences. Majority of these studies focus on Newtonian fluids between coaxial discs, where the dimensions of the liquid bridge are on the millimeter scale. Presented in this thesis is the characterization of liquid bridges that stabilize into polymeric fibres that are 10 cm long, while being less than 20 μm in diameter. To control the fibre formation process, a horizontal single-fibre contact drawing system was created, consisting of a motorized stage, a micro-needle, and a liquid filled reservoir. Analyzing liquid bridge rupture statistics as a function of elongation speed and solution properties revealed that a single timescale governed the fibre formation process. Using the reptation model for the viscoelasticity of the entangled polymer solution showed that this timescale corresponded to the relaxation time of entanglements. Characterization of the final fibres revealed that fibre diameter was proportional to the initial solution viscosity due to a secondary flow that occurs during the fibre formation process. Verification of these results with the addition of type I collagen demonstrates the significance of these findings in potentially using this contact drawing method for biomaterial fabrication.