Semester

Summer

Date of Graduation

2014

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Chemical and Biomedical Engineering

Committee Chair

Robin S. Hissam

Committee Co-Chair

Rajesh Naik

Committee Member

Edward Sabolsky

Committee Member

Charter Stinespring

Committee Member

John Zondlo

Abstract

The introduction of inorganic nanoparticles into organic materials enhances both the mechanical and chemical properties of the material. Metallic nanoparticles, like silver and gold, have been introduced into polymers for use as antimicrobial coatings or dielectric materials, respectively. The challenge in creating these materials currently is the difficulty to homogeneously disperse the particles throughout the polymer matrix. The uneven dispersion of nanoparticles can lead to less than optimal quality and undesired properties. By creating a polymer nanocomposite material with well-controlled size inorganic materials that are evenly dispersed throughout the polymer matrix; we can improve the materials performance and properties. The objective for this research is to use polymer networks for the in situ mineralization of silver and other metallic materials to create intricate inorganic structures.;The work performed here studied the ability to nucleate silver nanoparticles using poly (acrylic acid) (PAA) as the templating agent. Ionic silver was chemically reduced by sodium borohydride (NaBH4) in the presence of PAA. The effect of varying reactant concentrations of silver, NaBH 4, and PAA on particle size was studied. Reaction conditions in terms of varying temperature and pH levels of the reaction solution were monitored to observe the effect of silver nanoparticle size, shape, and concentration. By monitoring the UV spectra over time the reaction mechanism of the silver reduction process was determined to be an autocatalytic process: a period of slow, continuous nucleation followed by rapid, autocatalytic growth. The reaction kinetics for this autocatalytic process is also reported.;PAA was crosslinked both chemically and physically to 3 biopolymers; ELP, an elastin like peptide, cotton fabrics, and calcium alginate hydrogels. Various compositions of PAA were physically crosslinked with calcium alginate gels to design an antimicrobial hydrogel for use in wound dressing applications. PAA's ability to nucleate nanoparticles in a solid matrix was displayed. Interestingly enough PAA retains its ability to nucleate nanoparticle even when its reactive functional groups are used in the crosslinking process. Silver nanoparticle composition and size on the solid polymer matrices was controlled by varying the composition of PAA. PAA and silver nanoparticles effect on the mechanical properties of the calcium alginate hydrogels were also studied. Physically crosslinking PAA with calcium alginate gels enables the development of intricate gel structures that are decorated with nucleated silver; yielding a composite biomaterial with improved and enhanced antimicrobial properties.

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