Date of Award

8-2010

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Materials Science and Engineering

Advisor

Brown, Philip J

Committee Member

Mefford , Olin T

Abstract

Nanocomposites of nanoparticles dispersed throughout a polymer matrix have been studied to great length to improve the overall polymer properties. These enhancements are observed in the thermal, physical, and/or optical characteristics. Being able to harness nanoparticles in such a way may help improve fiber technology into the 21st century.
This work was geared toward synthesizing rare earth doped lanthanum fluoride (LaF3) nanoparticles because good separation in the absorption and emission bands of the material and it fluoresces in the visible to near-infrared range. Terbium ions were added to a LaF3 crystal because of their distinct visible green (545 nm) emissions. Organic ligands were utilized to control particle growth and stabilize particles in organic and polymer media. These ligands also absorb ultraviolet light via photo-excitation of π conjugated phenyl rings, transferring this energy to the lanthanide ions.
Lanthanide ions are protected by the LaF3 host to minimize quenching when added to a polymer. Hydrocarbon polystyrene and poly(methyl methacrylate) were the chosen matrix due to their inherent transparency/optical clarity and ease to melt process. Particles were loaded into these materials in such a way to maintain particle size and dispersion via a precipitation and an in situ polymerization method. Several techniques were utilized in the formation of loaded polymer film and fibers which included a twin-screw microcompounding film extruder and bi-component fiber extruder.

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