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Swellable Polymer Substrates For Use In Magnetochemical And Optical Chemical Sensing, Stephen Arnold Doherty

Doctoral Dissertations

Lightly cross-linked, animated polymers that swell and shrink with changing pH were prepared and evaluated. At low pHs amine sites protonate causing charge to accumulate along the polymer backbone. The polymer then swells to maximize the charge separation. The swelling of the polymer causes a change in a magnetic or optical property that can be measured and related to pH.

Animated hydrogel membranes were prepared by copolymerizing dimethyl amino ethyl methacrylate(DMAEMA) with various comonomer hydrogels. Experiments were conducted to examine the effect of formulation on the ability of the hydrogel membrane to swell. Factors examined included cross-linker type, cross-linker concentration, …

Nitrated Poly(4 -Hydroxystyrene) Microspheres For Optical Ph And Potassium Ion Sensing Based On Turbidity Changes Accompanying Polymer Sweller, Hongming Wang

Doctoral Dissertations

Porous poly(4-acetoxystyrene) swellable microspheres with diameters approximately 1∼2 mum were prepared by seeded emulsion polymerization. Toluene was used as the porogenic solvent and divinylbenzene was used as the crosslinker. The seed particles with diameters approximately 0.5∼1 mum were prepared by dispersion polymerization without adding porogenic solvent and crosslinker. Functionality was introduced by two derivatization reactions, hydrolysis and nitration, to form nitrated poly(4-hydroxystyrene). These polymer microspheres swell at high pH due to the deprotonation of the hydroxyl group on the polymer backbone. Swelling is accompanied by an increase in water content which causes the polymer refractive index to decrease. These microspheres, …

A Non-Derivatization Approach To Hplc Fluorescence Detection For Some Important Amino Group-Containing Compounds Based On A Ligand Displacement Reaction, Min Yang

Doctoral Dissertations

Detection of some important amino group-containing compounds such as amino acids, aliphatic biogenic amines and aminoglycosides can present difficulties since these compounds do not possess strong fluorophores or chromophores. A novel indirect fluorescence detection method for these compounds has been developed, taking advantage of the fact they form complexes with Cu 2+ ions. The reaction between these compounds and a Cu(II)-L-tryptophan complex (Cu(L-Trp)2) in solution results in the displacement of L-Trp from the complex and an increase in L-Trp fluorescence, since the fluorescence of L-Trp is quenched in the Cu(II) complex. The increase in L-Trp fluorescence is taken as the …