Fabricating poly(lactic acid) and poly(lactic acid)/poly(caprolactone) blend fibres via electrospinning

The whole thesis is divided into 8 chapters. Chapter 1 introduces some background information of the polylactic acid (PLA), poly(caprolactone) (PCL) and electrospinning which are the main polymers and technique used for this PhD project.

Chapter 2 is a comprehensive literature review related to the project, which firstly introduces nanofibres and various methods to fabricate nanofibres, followed by introducing different setups of electrospinning and the main factors (concentration, molecular weight and solution properties) influencing electrospinning results. Next, previous studies on electrospun, PLA-based, PCL-based and PLA/PCL blend fibres are reviewed. The final part is a critical review of porous polymeric fibres fabricated by different mechanisms and various applications in which electrospun porous fibres show improved performance (tissue engineering, drug delivery and oil spill clean-up & oil/water separation).

Chapter 3 is the experimental methods part of the project, which includes preparation of spinning solutions, electrospinning conditions and parameters, and a variety of techniques to characterise spinning solutions and the resultant fibres.

Chapters 4, 5 and 6 are results and discussion of the whole PhD project. Chapter 4 is focused on electrospinning of PLA, PCL and PLA/PCL nonporous fibres by using different solvent systems including acetone (AC) or AC/dimethylformamide (DMF), AC/ethanol (EtOH) and AC/dimethyl sulphoxide (DMSO). Also, the effect of blending ratio and applied voltage on fibre morphology and diameter have been studied. In addition, PLA incorporating magnetic particles (Fe3O4) has been electrospun into randomly oriented or aligned fibres. Chapter 5 investigates electrospinning of porous PLA fibres by careful selection of solvents, such as single solvent Chloroform (CHL) and DMSO or binary solvents: (CHL/EtOH and CHL/DMSO). The controlled surface and internal porosity can be attributed to mechanisms including breath figure, non-solvent induced phase separation (NIPS) and vapour induced phase separation (VIPS). Chapter 6 investigates fabrication of electrospun porous PLA, PCL and PLA/PCL blend fibres by the NIPS mechanism at given conditions (10kV, CHL/DMSO 80/20 %v/v). Properties, including shear viscosity of solutions, morphologies, phase inversion, thermal, mechanical and in vitro degradation of porous fibres are also studied in detail.

Chapter 7 concisely summaries the results and some discussion of the whole thesis. Chapter 8 suggests some future work that can be done.