| Summary: | Cellulose is the most abundant renewable and biodegradable natural polymer. Cellulose
can release nanocrystalline cellulose (NCC). NCC is light-weight, biodegradable and
strong. The strength of NCC is about 10 GPa, which is almost three times stronger than
commercial high performance fibre such as Kevlar® and Spectra®. In order to realize the utmost translation of NCCs’ extraordinary properties to higher order structures, it is necessary
to accomplish a well-controlled alignment and tailored distribution of NCCs within a matrix. However, it is challenging to achieve this goal since NCCs tend to agglomerate in matrix materials. To address this problem in the present study, NCC water- in-oil (W/O) emulsions were
prepared, consisting of a drop phase of NCC aqueous suspension and a continuous phase of immiscible poly (lactic acid) (PLA) solution. NCC W/O PLA emulsions were electrospun
into NCC reinforced nanocomposite fibres. The concept of emulsion electrospinning of NCCs is based on that (1) NCC can be stably and uniformly dispersed in the intermediate medium water; (2) NCC aqueous suspension can be dispersed in the form of droplets into the immiscible solutions of PLA solution system; and (3) the well dispersed NCC / PLA emulsion can be electrospun into fibres. In this work, to better control electrospinning of NCC/PLA emulsions, we started with electrospinning of W/O PLA emulsions consisting of a drop phase of distilled water and a
continuous phase of hydrophobic PLA solution. This emulsion formulation for electrospinning was optimized using response surface methodology (RSM) to identify the optimal conditions for W/O PLA electrospinning. After optimizing the W/O PLA emulsion
electrospinning process, the feasibility of the emulsion electrospinning of NCC W/O PLA
was confirmed and the emulsion electrospun 5% NCC/ 8% PLA random fibre mats and aligned fibre yarns were collected. The distribution and alignment of NCCs in fibres were verified. The morphology, structure and properties of resultant fibres were characterized. The mechanism of the formation of fibre structure (core-shell and hollow) was also proposed and validated by the study of emulsion droplet size effect on fibre structure.
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