New advances and applications in electrospinning of soft materials.
Doctoral thesis, UCL (University College London).
Electrospun fibrous structures are providing solutions to many problems such as biomedical, environmental and energy issues. Despite the exponential growth of interest, limitations still exist in optimising the process. In this dissertation, new advances and applications of electrohydrohynamic spinning and processing were explored to meet current demands and challenges encountered in the processing of electrospun biomaterials. Good electrospinnability refers to consistent fibre production with minimal ‘bead-onstring’ formation during electrospinning. One challenge is the solvent selection process, which significantly affects electrospinnability and the as-spun fibre morphology. This is mostly done by trial-and-error and the effect of solubility in solution-electrospinning have been neglected or taken for granted. The general concept is that a suitable solvent should have solubility parameters close to that of the polymer. However, literature has abundantly suggested a solvent may dissolve a polymer well, but whether the resultant solution is electrospinnable cannot be guaranteed. A novel method to systematically select and mix solvents for solution-electrospinning was developed in the first section of this work. The results were combined on the Teas graph to create a new “spinnability–solubility map”, allowing topographic analysis on the potential electrospinnability of a solvent or mixed solvents. Marginal solvents were shown to allow lower critical minimum solution concentrations – a parameter required for electrospinning to occur. Since fibre diameter depends on concentration, a lower critical concentration translates to finer fibres. Key properties of a solvent promoting elongation during electrospinning were also identified and the significant effects of the spinning environment on the polymer solution and the final fibre morphology were discussed. Unique fibrous relics were electrospun from poor solvents at elevated temperatures. Collaborating with the food industry, the application of electrohydrodynamic spinning and processing in food sciences was investigated, using edible biomaterials such as ethyl cellulose and chocolate. The potential to control fibre aspect ratio and directly electrospin short microfibres was studied.
|Title:||New advances and applications in electrospinning of soft materials|
|Additional information:||Permission for digitisation not received|
|UCL classification:||UCL > School of BEAMS > Faculty of Engineering Science > Mechanical Engineering|
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