The behaviour of surfactant at an oil-water interface is of fundamental importance across a range of application, one of which is detergency. For the characterisation of various anionic and non-ionic surfactants, which make up commercial detergent solution, at the aqueous-organic interface, electrochemical methods combined with conductivity, electrocapillary curves and optical microscopy were employed. The findings have revealed that the adsorption and partitioning of the anionic surface active ions at the interface between two immiscible electrolyte solutions can cause reproducible chaotic effects at the region of transfer potentials of the surfactant ions. Factors such as the Marangoni effect and spontaneous emulsification at the phase boundary, as well as the presence of micelles, micellar emulsification and transfer of emulsion droplets across the interface have been found to contribute to these chaotic currents at the organic-water interface. By applying cyclic voltammetry and chronoamperometry techniques, it was established that the irregular oscillations became more pronounced as the concentration of sodium dodecylbenzene sulphonate (SDBS) was increased from 1.5 mM -13.4 mM and the current spikes dissipated as the concentration of triton- x- 114 was increased from 8.6 mM - 114 mM in the aqueous phase consisting of 13.4 mM of SDBS. Similar results were obtained using P&G’s Y and N surfactants. The rise in current instability due to enhanced concentration of the SDBS, which was used as the standard surfactant, was confirmed using chronoamperometry, conductivity measurements and electrocapillary curves. The interfacial instability was prominent in the presence of electrolytes at the aqueous-1,2-DCE/oil phase boundaries which was visually evident in the optical microscopic images obtained. Furthermore, needle-like crystals were identified at the aqueous-1,2-DCE interface with electrolytes, with and without the addition of anionic/non-ionic surfactants. This suggests that a crystallisation process was initiated by the presence of dehydrated salt ions at the phase boundary, which is likely to be promoted by the surfactant ions. Lard has been used as the fat ‘model’ for washing experiments since it is composed of more problematic high melting point components compared to other sources of fat. Lard was deposited onto fabrics and left to age over a period of 4 hours at 20 °C and also, at the temperatures of -10 °C, 10 °C, 20 °C and 30 °C for 5 days. These samples, when analysed using the small angle X-ray scattering (SAXS) technique.

Soil release polymers (SRPs) are additives components of washing detergents for synthetic fibres, as they are effective in removing stains from the fabric surface and in preventing re-deposition of the stain during a wash cycle. Currently, there are no SRPs which can be used to efficiently perform the same function for natural cellulose based textiles. In this work, the synthesis of functional carbohydrate-based materials for application as potential SRPs for cellulosic surfaces was discussed. Two strategies were developed, exploiting the affinity of polysaccharides to adsorb over cellulose surfaces. The first strategy involved the synthesis of a co-polymer between poly(ethylene glycol diacrylate) (PEGDA), ethylenediamine and maltose, through a three step procedure. During the first step, the co-polymer backbone was synthesised through the co-polymerisation of PEGDA with N-Boc-ethylenediamine in bulk at room temperature. Then, the second amine functionality was de-protected and reacted with maltose to yield the desired co-polymer. The structure was confirmed through 1H and 13C NMR spectroscopy in solution, and through diffusion studies. The second strategy aimed to tune the strong affinity of carboxymethyl cellulose (CMC) for cellulose surfaces through grafting of poly(ethylene glycol) (PEG) chains. A variety of co-polymers were synthesised comprising different proportions of PEG bound. The co-polymers were characterised through a series of techniques, such as 13C solid state NMR, 1H gel state NMR, pulse field gradient NMR spectroscopy (PFG NMR) and size exclusion chromatography (SEC) in DMF. The potential of the co-polymers for application as SRPs was evaluated through soil release and whiteness tests. Furthermore, a preliminary study on the adsorption of two fluorescently labelled CMC-g-PEG co-polymers over cotton surfaces was conducted by means of fluorescence measurement.

The interactions between an optical brightener and surfactants commonly found in laundry detergents were studied. Three techniques were used; fluorescence spectroscopy was used to determine the effect of the addition of surfactants on the rate of brightener deposition, while small-angle X-ray scattering (SAXS) and molecular dynamics (MD) simulations were used to determine the effect of the brightener on the micellar structure pre-deposition. In addition, the effect of calcium ions on micellar structure was studied using these techniques. The effect of surfactant addition on CaCO3 crystallisation was also studied. It was found that the addition of nonionic surfactants inhibited the deposition of brightener onto fabric surfaces, whereas the addition of anionic surfactants aided this deposition process. This was correlated to the micellar structures found using SAXS and MD simulations; the anionic surfactant system formed ellipsoidal structures, in which the brightener was incorporated onto the surface of the hydrocarbon core, whereas the nonionic surfactant formed spherical structures where the brightener was held within the outer shell, which appeared to hamper its ability to be deposited. In addition, the brightener was shown to affect micellar radius and aggregation number of the nonionic surfactant, in a manner similar to the addition of anionic surfactant to nonionic surfactant. The addition of calcium ions at concentrations up to 0.36 g L-1 Ca2+ (for SAXS) and 0.77 g L-1 Ca2+ (for MD simulations) to nonionic and anionic surfactant systems was not seen to significantly affect their micellar structure, although a greater affinity was seen between the calcium and the anionic surfactant than between the calcium and the nonionic surfactant. The effect of the addition of surfactants on the rate of CaCO3 crystallisation and the polymorphs produced was determined.

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This research study aimed at using renewable resources from biomass to generate novel polymers and surfactants for applications in Home and Personal Care products. Esterification, transesterification, epoxidation and ring opening reactions were applied with the instrumentality of clean synthetic techniques to deliver over sixty nonionic surfactants with main hydrophilic head containing 9-34 units of ethylene oxide (EO) and hydrophobic tail containing C19-28 hydrocarbons from oleate derivatives, epoxidised linseed oil and sophorolipid. The surfactants were fully characterised with nuclear magnetic resonance spectroscopy, super-critical fluid chromatography, differential scanning calorimetry, electrospray ionisation-mass spectrometry and infrared spectroscopy. Surfactants properties were assessed based on physicochemical measurements and hydrophilic-lipophilic balance. The synthesised polymeric surfactants have great potential applications ranging from oil-in water emulsification, wetting and spreading, detergency and to solubilisation purposes, and can be incorporated into Home and Personal Care products. Alongside the above study, attempts were made to convert 2,5-furan dicarboxylic acid to diethyl terephthalate as a step to making 100% bio-based poly(ethylene terephthalate), and vital plastic packaging for Home and Personal Care formulations. The bio-based aromatic monomer was synthesised via Diels-Alder addition of diester of the furan to ethene under a solventless system catalysed by in-expensive heterogeneous Lewis acid catalysts. DET yield up to 59% was obtained, this being a substantial improvement compared to yields for the same or similar reaction of FDCA and its esters reported elsewhere. The synthetic route herein described was compared with other published biomass routes to bio-based PET using green chemistry metric toolkits, and ours stands as the preferred biomass route based on this comprehensive assessment.

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During the 1990's the development of metallocene catalysts has made a dramatic impact on the polyethylene industry. A large amount of work can be found in the literature regarding the degradation and stabilisation of conventional polyethylenes. However, very few studies have been devoted to these novel metallocene polymers. The first part of this thesis deals with the thermo-oxidative degradation of various metallocene polyethylenes (mPE's) in the solid state (oven ageing at 90°C in air) and the melt state (via mastication in air in a Brabender® mixer). For each mPE, essentially one characteristic (melt index, molar mass distribution, density and ash content) was changed at a time. In the second part, the effect of different grades (animal versus vegetable) and types (calcium versus zinc stearates) of metallic stearates in combination with phenolic and phosphite antioxidants was investigated in the melt stabilisation of a standard metallocene LLDPE (mLLDPE). Finally, interactions between additives present in a typical stabiliser package used for film grade LLDPE were assessed in the stabilisation of the mLLDPE with help of a two-level factorial design of experiments. The response included melt flow protection and discolouration during processing, as well as long-term stability. Outstanding thermo-oxidative stability was exhibited for all the mPE's in the solid state. This remarkable oxidative stability was believed to be due to the presence of low concentrations of innocuous metal catalyst residues, as well as low initial vinyl unsaturation content and degree of branching. Furthermore, polymer density/crystallinity appeared to reduce the spreading rate of oxidation. In the case of thermo-oxidation in the melt state, the polymer melt viscosity appeared to govern the processing stability of the metallocene polymers. In the second part, it was found that the quality of the metal stearates, i.e., peroxide content, metal oxide and unsaturation, may affect the performance of the phenolic and phosphite antioxidants in the melt stabilisation of the mLLDPE. Finally, the statistical design of experiments proved to be a very useful tool for screening the effects of each additive and the possible interactions between additives present in the investigated stabiliser system.

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