"Optical Detection of Process Parameters in Structural Polymer Nanocomposites Using Gold Nanorods"

ABSTRACT:
The real-time measurement of thermophysical properties in structural polymers is crucial to the optimization of processing parameters for composites manufacturing. However, robust techniques for in-situ monitoring of key parameters such as temperature, stress, strain, viscosity, and degree of cure with high sensitivity and spatial resolution are lacking. Many optically active nanoparticles, including fluorescent quantum dots and plasmonic nanostructures, change their optical signatures in response to various environmental stimuli. These materials are good candidates for embedded sensing in polymers because of their high signal-to-noise and intrinsic non-contact sensing modality. However, because spectral shifts can arise through a variety of mechanisms, a thorough understanding of the fundamental relationships between environment and optical response is needed. I will show that the thermal shape transformation of gold nanorods in a polymer matrix is governed by multiple mechanisms, and these competing mechanisms lead to different behaviors at short and long time scales. This understanding can be exploited in order to use gold nanorods as a way to simultaneously measure temperature, dielectric constant, and modulus in a structural polymer resin.

BIO:
(William) Joshua Kennedy received his Ph.D. in Physics from the University of Utah in 2011. His graduate work and early postdoctoral work at the University of Texas - Dallas was focused on the study of the optoelectronic properties of carbon nanotubes and nanotube polymer nanocomposites. During a postdoctoral fellowship at Nasa Johnson Space Center, Dr. Kennedy studied the functional response of optically active polymer nanocomposites for space applications, and he developed a new piezoelectric composite for use on the International Space Station. Dr. Kennedy now works as a Research Physicist at the Air Force Research Laboratory at Wright-Patterson Air Force Base in Dayton, OH. He is a member of the Polymer Matrix Composites Materials and Processes Research Team where he focuses on the development of multifunctional structural composite materials and embedded sensors for composite processing.