Wet spinning of core-shell and hollow polyelectrolyte fibers

  • Nassspinnen von Kern-Schale- und Hohlfasern aus Polyelektrolyten

Cui, Qing; Wessling, Matthias (Thesis advisor); Pich, Andrij (Thesis advisor)

Aachen : RWTH Aachen University (2021)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021

Abstract

Structured polymeric fibers have been widely researched and applied to various industrial fields in the past decades. This thesis aims at utilizing wet spinning technology to achieve fabrication of polymeric fibers with different structures, and making full use of the spun functional fiber materials in tissue engineering and electrochemical reactions. Polyelectrolyte complex fibers (PEC fibers) have great potential with regard to biomedical applications as they can be fabricated from biocompatible and water-soluble polyelectrolytes under mild process conditions. This thesis describes a novel method for the continuous fabrication of PEC fibers in a water-based wet-spinning process by interfacial complexation within a core-shell spinneret. This process combines the robustness and flexibility of non-solvent-induced phase separation (NIPS) spinning processes conventionally used in the membrane industry with the complexation between oppositely charged polyelectrolytes. In the case of chitosan and polystyrene sulfonate (PSS), mechanical fiber properties could be enhanced by doping the PSS with poly(ethylene oxide) (PEO). The suitability of the CHI/PSS-PEO fibers as a scaffold for cell culture applications was verified by a four-day cultivation of human HeLa cells on PEO-reinforced fibers with a subsequent analysis of cell viability by fluorescence-based live/dead assay. Hydrogen peroxide is widely applied in chemical synthesis, electronics, paper and textile industry, obtaining an increasing global market demand during the past decade. This thesis describes a PEDOT: PSS/CNTs composite material for catalyzing the twoelectron pathway of oxygen reduction reaction and further studies the influence of CNT additives (0-40 wt.%) on the PEDOT: PSS system. The composite demonstrated the highest conductivity of 484 S/cm and an optimum capacitance of 82.59 F/g. Acid-treated pure PEDOT is for the first time proved to be a 2-e ORR catalyst. With a self-designed core-shell spinneret, 40 wt.% composite hollow fibers can be easily fabricated in a onestep bottom-up wet-spinning process. These hollow fibers performed an H2O2 production rate of 0.0108 mg/min/cm2, a current efficiency at 54.3% under -0.25 V (vs. SHE) and relative current retention of 95.1% after 20h’ experiments, which is highly competitive compared to literature.

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