Four new N-isopropylacrylamide (NIPAM) based particles have been synthesized and characterized. The first experimental chapter reports that fluorescent poly(Nisopropylacrylamide-co-5% vinyl cinnamate) microgels were deposited on different solid surfaces to produce new environmental responsive surfaces. The mass of microgel particles deposited on glass pre-treated with acid, glass pre-treated with base, quartz, stainless steel, gold and Teflon at 25°C and 60°C was determined using fluorescence spectroscopy. The factors affecting the adsorption/desorption of the microgel particles were also investigated. The study shows that the solid surface charge is the most significant factor, followed by that of surface roughness and temperature; meanwhile, the hydrophobicity/hydrophilicity of the surface was the least significant. Fluorescent temperature/pH responsive p(NIPAM-co-5% acrylic acid)-rhodamine B particles were studied. The results confirm the attachment of rhodamine B to the microgel particles. The long chains attached to the particles caused the particles to be poly-dispersed which suggests non-uniformity of particle size and behavior. Fluorescent temperature/pH responsive poly(N-isopropylacrylamide-co-5% lucifer yellow) (p(NIPAM-co-5% LY)) microgel particles were tested for toxicity. The particles were negatively charged, mono-dispersed and were approximately 250 nm in diameter at 15°C. The toxicity of different concentrations of p(NIPAM-co-5% LY), p(NIPAM) and NIPAM monomer was tested on two cell lines (HeLa and Vero). The results show that the two particles maintain cell viability over 80% (for both cell lines HeLa and Vero) up to a concentration of 3 mg/mL while NIPAM monomer showed a cell viability of over 80% at a concentration equal to or less than 0.3 mg/mL. The fourth experimental chapter explores the opportunity of using microgel particles as an emulsifier. p(NIPAM-co-5% acrylic acid)-hexenol particles with both hydrophilic and hydrophobic groups in their molecular structure were used to stabilize two emulsions (tricaprylin-in-water and hexadecane-in-water). The stability of the emulsions increased with increasing the concentration of the microgel. For the tricaprylin-in-water emulsion, a concentration of 0.3% w/v of the novel microgel particles managed to stabilize the emulsion for a week. In case of the hexadecane emulsion in water, 0.45% w/v microgel particles could show an increase in the emulsion stability and a decrease in the creaming.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:732827 |
| Date | January 2015 |
| Creators | Mohsen Momee, Reham M. |
| Contributors | Snowden, Martin ; Alexander, Bruce |
| Publisher | University of Greenwich |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://gala.gre.ac.uk/18140/ |
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