Doctoral Thesis Defence
Friday 08th of October 2021 at 4:00 pm Campus Limpertsberg, Room BSC 0.03 Webex
Talk by Shameek Vats Supervisor: Professor Jan Lagerwall
Electrospinning Core-Sheath Functional Fibers
Wearable technology in general has increasingly gained interest in the last few decades and textile incorporated with
functional component is one form of it. There are multiple ways to produce polymer fibers on both laboratory and industrial
scales, and one of them is core–sheath electrospinning, which is a powerful method for producing advanced composite
fibers. Liquid crystals (LCs), are materials that readily exhibit optical response to fluctuations and change in their immediate
environment. By incorporating LC within polymer fibers through the electrospinning, it is possible to create responsive
LC-polymer fiber mats. However, incorporating a functional core has proven challenging for certain combinations of
materials. This thesis explores and addresses some of the concerns involved in the coaxial electrospinning of fibers
incorporating LCs from several standpoints.
Firstly, the effect of solvents on the electrospinning process was systematically studied. Following this, an optimum
viscosity with pure and mixed solvents for successful electrospinning was identified and uniform fibers with different
solvent combinations was produced. Using the knowledge gained, core-sheath electrospinning with LC as the core was
carried out. One of the key findings of this work was, the identification of a suitable means to reduce the interfacial tension
between the core and sheath fluid to prevent breakup of the jet and produce uniformly filled fibers, while at the same time
avoiding complete mixing between core and sheath.
These findings can be applied to any combination of core and sheath materials and should appeal to large community of
researchers.
Eventually, to achieve the durability of the LC-functionalized electrospun fiber mats for use in wearable technology, the
sheath polymer of the fibers was crosslinked after spinning. The resultant crosslinked fibers were easily manipulated by
hand and even fully immersed in water without dissolving and without losing their functional LC core.
Dissertation defence committee:
Chairman: Dr. Anupam Sengupta, Assistant Professor, Université du Luxembourg
Dr Giusy Scalia, ADR, Université du Luxembourg
Dr. Maria-Helena Godinho, Associate Professor, Universidade Nova de Lisboa
Dr. Margaret Frey, Professor, Cornell University
Dr. Jan Lagerwall, Professor, dissertation supervisor, Université du Luxembourg