Amphiphilic electrospun fibres of poly(methacrylic acid)-graft-poly(dimethylsiloxane) copolymers as a means to controlling electrospun fibre morphology and obtaining nanofibre hydrogels

Meltz, Freda-Jean (2014-04)

Thesis (MSc)--Stellenbosch University, 2014.

Thesis

ENGLISH ABSTRACT: Novel poly(methacrylic acid)-graft-poly(dimethylsiloxane) copolymers were synthesised by conventional free radical reactions using a poly(dimethylsiloxane) macromonomer. The polymers were electrospun to investigate how the fibre morphology can be modified by manipulating the electrospinning solution parameters, and to determine the possibility of using the polymers as new materials for the production of polymer nanofibre hydrogels. The electrospinning solution parameters were varied by electrospinning the highly amphiphilic copolymers in solvents with variable solvent qualities. Scanning Electron Microscopy (SEM) and Field Emission Scanning Electron Microscopy (FE–SEM) was used to investigate the fibre morphology. Internal morphology was studied using a freeze fracture technique prior to FE-SEM imaging. It is revealed that the polymers in this study does not form any fine structure or pores even when self-assembled structures are present in the solution. Attempts were made to visualise any self-assembled structures of films produced from dilute solutions using TEM. Further studies included investigating the fibres properties, primarily with regards to their rate and extent of moisture and water uptake. The fibres showed hydrogel behaviour and the PDMS content were found to have an impact on the hydrogel stability. Post electrospinning crosslinking of the nanofibres was also explored.

AFRIKAANSE OPSOMMING: Unieke ent-kopolimere wat bestaan uit poli(metielakrielsuur) (PMAS) en poli(dimetielsiloksaan) (PDMS) is gesintetiseer deur middel van 'n “ent-deur” vryeradikaalkopolimerisasie. 'n PDMS makromonomeer is vir hierdie doel gebruik. Die polimere is geëlektrospin om vesels te vorm. Die doel was om die invloed van verkillende strukture in oplossing op die veselmorfologie te bepaal. Die moontlikheid om hierdie nanovesels as gels te gebruik is ook ondersoek. Die amfifiliese kopolimere is geëlektrospin uit die oplossing waarin dit wisselende oplosbaarheid toon. Skandeer elektron mikroskopie (SEM) is gebruik om die morfologie te ondersoek. Die interne morfologie van die vesels is ondersoek deur die vesels te vries en in die gevriesde toestand te breek. Die studie het getoon dat geen strukture op, of binne, die vesels vorm nie, selfs al moes daar assosiasie tussen segmente van die polimere gewees het. Hierdie tipe assosiasies sou strukture in die oplossing tot gevolg gehad het. 'n Poging is aangewend om die strukture in oplossing te visualiseer deur transmissie elektron mikroskopie (TEM) van dun films te ondersoek. Films is vanaf verdunde oplossings gevorm. Ander studies het ingesluit om die eienskappe van die vesels te ondersoek, met die fokus op hoeveel en hoe vinnig die vesels waterdamp en water kon absorbeer. Die vesels het soos 'n gel reageer. Hierdie gedrag is beïnvloed deur die hoeveelheid PDMS wat 'n definitiewe invloed op die stabiliteit van die gel gehad het. Kruisverbindings van die vesels, nadat dit geëlektrospin is, is ook ondersoek.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/86620
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