Semester

Spring

Date of Graduation

2012

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Robin S. Hissam

Committee Co-Chair

Edward Sabolsky

Abstract

A growing need for nanoparticle-polymeric composite materials in the electronics and coatings industries has driven research to gain a better understanding of the mechanisms of self-assembled phase separation in polymer thin films and experiment with controlling the phase separation behavior of multicomponent polymer systems. This research proposed that biological polymers have the ability to phase separate into defined structures capable of organizing nanoparticles with unparallel control over the architecture of the molecule compared to synthetic polymers.;This study used recombinant DNA techniques and the expression host E. coli to accurately and repeatedly produce a peptide with a random coil secondary structure. The peptide was blended with synthetic polymers or other peptides, and dried into films on silicon wafers. The films were evaluated with SEM and tapping mode AFM to assess the organizational behavior of multicomponent macromolecular systems. Some films were also exposed to nickel nanoparticles to investigate whether preferential binding to the peptide could organize nanoparticles in a composite material.;Promising AFM phase images of a hybrid blend of PAA and (GAGPGP) 12 peptide suggest phase separation, but when Ni nanoparticles were added, the nanoparticles only appeared to be well-dispersed and not necessarily organized in one phase domain. A blend of the slightly hydrophobic (GAGPGP) 12 peptide and a negatively charged peptide called VA2 also demonstrated signs of phase separation in the AFM phase images taken. However, when the film was exposed to a solution of Ni nanoparticles at high pH or the two peptides were coupled together, the film morphology changed drastically and no signs of phase separation were observed. The results of this research are significant because they suggest that biological polymers may phase separate in solid state films which is promising for various biomedical applications and is intriguing from a basic science point of view.

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