Yao-Chi Shu

Novel highly aligned, double-layered, hollow fibrous polycarbonate membranes with a perfectly tightly packed pentagonal pore structure fabricated using the electrospinning process

Highly aligned, tightly packed, single-, double-, and mixed-layer polycarbonate (PC) hollow fibrous membranes were prepared using two-fluid coaxial electrospinning. Polyethylene oxide (PEO) was used as the core, and PC was used as the shell; the PEO was subsequently extracted. The effects of the polymer concentration and spinning voltage on the morphologies and mechanical properties of the membranes were explored. At a PC concentration of 20 wt% and voltage of 8 kV, a hollow fibrous membrane (PC20-8) with a perfectly packed double-layered structure, high alignment of 97%, and distinct pentagonal pores (different from the typical quadrangle pore structure) was prepared. This membrane had the highest Youngs modulus and tensile strain, 1.8 GPa and 700%, respectively. The observed results suggest that highly aligned hollow fibrous membranes with favorable mechanical properties, particularly PC20-8, have potential for application in guide conduits for nerves, vascular scaffolds, and biomedical devices.

Physical Properties of Polydimethylsiloxane-Containing Elastomers and their Electrospun Nanofibre Mats

A series of polydimethylsiloxane-containing elastomers (S elastomers) were synthesised from 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (1,4-BD) and polydimethylsiloxane (PDMS). Through TGA analysis, S elastomers exhibited a four-stage degradation. The first and second stages resulted from the degradation of hard segment; the complicated degradation behaviour in the stages is associated with two hard-segment structures in the S elastomers. The third stage was the decomposition of PDMS, in which a cyclosiloxane degradation product was formed; subsequently, at a higher temperature it proved to be macrocyclics, which were degraded in the vicinity of 550 °C. Obviously, the degradation of S elastomers differed from the two-stage degradation of conventional polyurethane. Compared to conventional polyurethane, S elastomers presented better mechanical properties, showing the strength and elongation at break about 5.6~20.6 MPa and 550~830 %, respectively. With the better mechanical properties of S elastomers, nano-structured fibre mats were produced by electrospinning. Fibre morphology was observed by SEM and the effects of processing variables, including solution concentrations and voltages, on the morphology were evaluated.