Identifier

etd-01202005-163419

Degree

Doctor of Philosophy (PhD)

Department

Chemistry

Document Type

Dissertation

Abstract

Hierarchical construction and characterization of core-shell composite particles of interest are presented. The research described shows interest in new types of polymers that provide chirality and responsiveness which have been ignored for so long. The general synthetic design described in this document can be readily used as a model for other systems. Core-shell composite systems of interest consist of silica or silica-coated cobalt cores grafted with a homopolypeptide shell, mostly poly(epsilon-carbobenzyloxy-L-lysine) or poly(gamma-benzyl-L-glutamate). Core particles were decorated with amino groups through a silylation reaction. The amino groups initiated the polymerization (with attachment) of N-carboxyanhydride (NCA) monomers, resulting in a homopolypeptide shell. Homopolypeptide-grafted particles were considered as hierarchical systems due to the two levels of responsiveness. The first level of responsiveness is due to the superparamagnetic nature of the core and the second level of responsiveness is through the thermally responsive polypeptide shell. Both levels of response were confirmed with several characterization methods. Characterization by electron microscopy and dynamic light scattering (DLS) confirmed the uniformity of the particles. Magnetic properties of the silica-coated cobalt core and polypeptide-grafted particles were investigated with a superconducting quantum interference device (SQUID). DLS and digital polarimeter demonstrated helix-coil transitions of the particles through continuous heating and cooling cycles in m-cresol

Date

2004

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be handled under option 1 above, unless we request option 2 or 4 in writing.

Committee Chair

Paul S. Russo

Included in

Chemistry Commons

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