Date of Award

7-1-2014

Degree Type

Dissertation

University or Center

Clark Atlanta University(CAU)

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Ishrat M.Khan, Ph.D.

Abstract

Conjugated polymers have brought about a revolution in the world of polymers and hence, opened up new possibilities in the utilization of polymers in ways hitherto unknown. As a result of the conjugated bonds present, they are able to carry electrons and therefore mimic metals. One of the objectives of this work is the syntheses of processable conductive polymers in a cost effective manner that would still have desired physical and chemical properties. A series of electroative polymers have been prepared and most of these are intrinsically conductive. A semiconducting filler, single-walled carbon nanotubes, was added to impart conductivity to the functional polymer, α,ω-bi[2,4-dinitrophenyl caproic] [poly(ethyleneoxide)-b-poly(2-methoxystyrene)-b-poly(ethylene oxide)] which is non-conducting. Composites of this polymer with polystyrene and SWCNTs were electrospun to form nanofiber mats which had mixed morphologies but predominantly beaded. The nanofibers ranged in diameter form ~ 65 to ~ 500 nm. These functional nanofibers were incubated in fluorescently (FITC) tagged Immunoglobulin E, IgE and they showed biospecificity towards IgE. The current-voltage characteristics indicated a change in behavior when bound to IgE and otherwise.

The intrinsically conductive polymers of 3-alkylthiophenes were prepared using the Grignard metathesis reaction, oxidative coupling with ferric chloride as well as copolymerization via ATRP with conductive P3DT as the macroinitiator. These environmentally stable polymers show a glass transition mostly between 48 to 50 °C and the π to π* transition of the conjugated polymers is evidenced in wavelength of their absorption in the UV/Vis/NIR as the spectra indicated. The particle sizes obtained by light scattering showed average diameter between 28 to 40 nm for the different polymers.

Electrochemical studies on the block copolymer and random polymer series by cyclic voltammetry show the species are redox active in solution. Conductivity of multiwall nanotubes/ P3MT composite series showed conductivity values between 1.3 x 10-7 to 2.5 x 10-4 S/cm as determined from the bulk resistance measurements of pressed pellets of the composites. The biofunctional polymers investigated are highly promising in the biotechnology/biomedical industry as potential biosensors. The non-biofunctional polymers too are applicable in photovoltaics, optoelectronics, energy storage, solar cells, the semiconductor industry and many more.

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