Macromolecules incorporating a highly branched polystyrene core and a poly(ethylene oxide) shell were synthesized. A comb-branched (generation G = 0) polystyrene was prepared by initiating the polymerization of styrene with sec-butyllithium, capping with 1,1-diphenylethylene, and titrating the living anions with a solution of chloromethylated linear polystyrene. A twice-grafted (G = 1) core with protected hydroxyl end groups was obtained using (6-lithiohexyl)acetaldehyde acetal to initiate the polymerization of styrene, followed by capping and grafting on the chloromethylated comb polymer. The acetal functionalities were hydrolyzed, and the core was titrated in solution with potassium naphthalide, before adding ethylene oxide. To maintain a narrow apparent molecular weight distribution, it was necessary to eliminate residual chloromethyl sites by a metal−halogen exchange reaction, prior to shell growth. Core-shell polymers based on a G = 1 core with M̄ w = 7 × 105 g·mol-1 containing 19% and 66% poly(ethylene oxide) by weight were prepared, with apparent polydispersities M̄ w/M̄ n ≈ 1.1−1.2. Another sample incorporating a G = 4 core with M̄ w of ∼108 g·mol-1 containing 36% poly(ethylene oxide) by weight was also synthesized. The hydrodynamic radii of the core and core-shell polymers were determined by dynamic light scattering. Based on the M̄ w estimated for the poly(ethylene oxide) chains, the hydrophilic chains exist in a randomly coiled conformation. The solubility behavior of the macromolecules is consistent with a core-shell morphology:  the amphiphilic copolymers are easily desolvated from tetrahydrofuran solutions, giving transparent dispersions in water or methanol.

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Small-angle neutron scattering was used to measure the size and shape of arborescent graft polymers as a function of generation in solution. The radius of gyration of arborescent graft polymers was found to be almost independent of temperature in both deuterated cyclohexane (above the cloud point) and deuterated toluene. For dilute deuterated cyclohexane solutions the optically measured cloud point was found to be 15 ( 1 °C. Two peaks were observed in the SANS data for the phase-separated (below the cloud point) deuterated cyclohexane solutions of the largest polymers (generation 3). The first peak (at smaller scattering vector) is attributed to the interference between molecules while the second peak arises from the single particle form factor which was also observed at temperatures above the cloud point. In deuterated cyclohexane the position of the form factor peak was constant at temperatures above 15 °C. In the phase-separated deuterated cyclohexane solutions the form factor peak shifted to higher q, indicating a fractional decrease in molecular diameter of about 15% upon phase separation. The spacing of the interference peak (at low q) in the phase-separated solutions was consistent with the molecules aggregating in clusters with little interpenetration of the molecules. A power law function was used to model the real space density profile from which scattering curves were calculated and compared to the experimental data. This power law functional form for the density profile gave fits with smaller deviations from the experimental data when compared to either a hard or hollow sphere model.

The sol gel synthesis method was used to prepare carbon and nitrogen doped titanium dioxide (TiO2) photo-catalyst using titanium tetrachloride (TiCl4) as the precursor. Doping was carried out to modify the absorption band edge of titanium dioxide. To avert the problem associated with use of powder TiO2, the photo-catalyst was immobilized on glass support using tetraethyl orthosilicate (TEOS), which served as a binder and precursor for silicon dioxide (SiO2). The prepared photo-catalytic materials were characterized by FT-IR, XRD, TEM, BET and DRS. The photo-catalytic efficiency of titanium dioxide immobilized on glass support was evaluated using the degradation of methyl orange (MeO) and phenol red (PRed) under ultraviolet and visible light irradiation. Doping with carbon and nitrogen, and incorporation of silicon dioxide into the titanium dioxide matrix allowed utilization of visible light by the prepared TiO2-SiO2nanocomposites. Photo-degradation tests were carried out for doped and undoped photo-catalyst. An increased rate of photo-oxidation of methyl orange and phenol red was observed under visible light irradiation as compared to UV light irradiation.

The aim of this study was to prepare activated carbon from tobacco stalks using microwave heating. The prepared activated carbon was applied as an adsorbent in methylene blue (MB) removal from water. The optimum conditions for activated carbon preparation were a radiation power of 280 W for a period of 6 minutes after the impregnation of the precursor material with 30% ZnCl for 24 hours. The activated carbon yield and iodine number were 49.43% and 1,264.51 mg/g respectively. The activated carbon also had a point of zero charge of 5.81 with an adsorption capacity of 123.45 mg/g for MB. The optimum conditions for MB adsorption were a pH of 6.5 with an adsorbent dosage of 0.2 g/50 mL at 25 °C. The MB adsorption kinetics followed the pseudo second order kinetic model with the intra-particle diffusion model suggesting a two-step adsorption mechanism. The adsorption data also fitted well within the Langmuir adsorption isotherm model. Tobacco stalks can successfully be turned into an economically important product.