Soft Materials at Interfaces for Controlling and Studying Marine Biofouling, Cellular Growth, and Phonon Polaritons

• Main Author: Kim, Sanghyun
• Other Authors: Walker, Gilbert C, Chemistry
• Format: Thesis
• Language: unknown
• Published: 2019
• Subjects: Materials; Nano; Surface Science; 0485; Atlantic salmon
• Online Access: http://hdl.handle.net/1807/98787

Several â softâ material systems are investigated at the nanoscale through the application of surface sensitive techniques. The first family of projects focus on providing environmentally-friendly solutions to challenges faced in aquaculture, including marine biofouling and sea lice infestations. To address fouling, an aqueous-based method was developed for fabricating nanostructured block copolymer films. Specifically, a water-insoluble triblock copolymer, Poly(styrene-block-2 vinyl pyridine-block-ethylene oxide), was phase transferred from a water-immiscible phase into an aqueous environment, where it was found to self-assemble into core-shell-corona type micelles. These micelles were then coated onto surfaces to form thin films and adhesion studies using atomic force microscopy (AFM), zoospore settlement assays, and field tests reveal its ability to serve as a potential marine antifouling coating. Conventional drugs used to control sea lice infestations are becoming less effective as parasites grow tolerant and have been found to harm non-target local species. Here, I present the efficacy of biologically extracted ingredients to serve as potential biopesticides. Liquid chromatography and mass spectrometry techniques are developed and optimized to monitor the fate of azadirachtin (extracted from neem oil) when orally administered to Atlantic salmon and exposed to aqueous environments. Field trial results reveal that azadirachtin levels as low as 0.01 ppm accumulated in the tissue of salmon results in over 85% efficacy against sea lice, relative to controls. The next group of projects investigates properties of synthetic materials at the nanoscale. We show that by supporting hexagonal boron nitride (hBN) on materials with varying dielectric responses in the infrared results in control of surface momenta of hyperbolic phonon polaritons (HPhPs). Our results show that by supporting hBN on materials with higher dielectric responses leads to a higher surface momenta of HPhPs. Furthermore, propagating waves in hBN were found to be highly sensitive to the reflections at the upper and lower interfaces, which provides opportunities for energy to dissipate. The damping behavior of HPhPs was shown to be sensitive to adjacent layers and a method of applying HPhPs in hBN as a sensor is demonstrated. Ph.D. 2019-12-19 00:00:00