The functionalization of surfaces has received attention because the process allows the design and tailoring of substrate surfaces with a new or improved function. "Host-guest" thin film complexes are composed of "host" molecules attached the substrate surface, either through physisorption or covalent bonds, with cavities for the inclusion of desired "guest" molecules for the functionalization of the surface. Two methods for fabricating functional "host-guest" thin films were investigated: Langmuir-Blodgett (LB) deposition and self-assembly monolayer (SAM). Langmuir films were created at the air-water interface using octadecanesulfonic acid (C18S) as the amphiphilic "host" molecules separated by hydrophilic guanidinium (G) spacer molecules, which created a cavity allowing the inclusion of desired "guest" molecules. Surface pressure-area isotherms of the (G)C18S, with and without guests, are characterized by the lift-off molecular areas and are use to determine the proper deposition surface pressure. "Host-guest" Langmuir films are deposited onto silicon substrates using the LB deposition technique. The LB films were then subjected to stability testing using different solvents over increasing periods of time. Grazing-angle incidence X-ray diffraction (GIXD), specular X-ray reflectivity (XRR) and transfer ratio measurements were used to characterize the crystallinity, film thickness, overall film stability and film coverage. The GIXD data revealed that the crystallinity of the deposited film varies with the "guest" molecules and can be disrupted by the functional group on the "guest" molecule through hydrogen bonding. After modeling the XRR data using StochFit, it was discovered that the more polar solvent, tetrahydrofuran (THF), removed the film completely while the nonpolar solvent, hexane, compacted the thin film and increased the electron density. With transfer ratios around 0.95 to 1.05, the deposited films were homogenous. The second method used was self-assembly monolayers, which differs from Langmuir films in that they are created by a spontaneous chemical synthesis from immersing a substrate into a solution containing an active surfactant. Octadecyltrichlorosilane (OTS) was used initially as a molecule to study the self-assembled monolayer procedure. To study a "host-guest" self-assembled monolayer system, a compound is being synthesized from 9-bromoanthracene. This compound would already contain the cavity necessary for the inclusion of "guest" molecules. The solution that contained OTS was composed of a 4:1 mixture of anhydrous octadecane: chloroform. Silicon substrates with a deposited oxide layer were hydroxylated for the surfactant binding chemical reaction to occur. The OTS SAMs were exposed to the same stability tests as the LB films. Surface contact angle measurements were taken of the OTS SAMs before and after the stability tests. The contact angle prior to the stability tests was 110° (±2°). The contact angle after immersion in THF was 101° (±2°) while the contact angle resulting from immersion in hexane was 105° (±2°). From the contact angle measurements, the degradation of the OTS SAMs was less extensive than that of the (G)C18S LB films. / Master of Science

<p dir="ltr">Developing functional metallic nanostructured surfaces has seen significant growth in various applications, including sensors, electronics, and biomedical devices. However, conventional fabrication techniques for these nanostructures face limitations such as complexity, high costs, and unstable coatings. Laser-assisted surface processing has emerged as a promising solution to address these challenges by enabling localized processing and modification without altering bulk properties. This dissertation focuses on the development of multifunctional devices using selective laser processing of metallized surfaces, categorized into three routes. The first part explores the utilization of laser-induced oxides (LIO) for simple processing and formation of functional metal oxide nanostructures as electrochemical sensing elements. Different laser processing conditions were systematically studied for cost-effective metals like copper and nickel, evaluating their potential as non-enzymatic glucose sensors. The second part investigates laser selective processing for removing metal coatings on temperature-sensitive substrates, providing a cost-effective and scalable alternative to conventional photolithography and etching processes. Various laser processing conditions were examined to achieve selective patterning of metalized fabric structures for wearable electronics production. The third part explores localized laser processing to create intermetallic nanotexturing mixtures without altering bulk properties. The study involved silver spray- coating onto titanium implants, followed by a post-laser processing. The aim was to achieve simultaneous texturing and intermixing of silver in titanium alloy structures, enhancing antibacterial properties and bone mineralization while preserving mechanical properties.</p><p dir="ltr">Through the comprehensive examination of these three routes, this dissertation demonstrates the immense potential of commercial laser processing systems in the design, fabrication, and characterization of functional metallic nanostructured surfaces. It emphasizes the often-overlooked aspect of chemical alterations in laser-assisted surface processing, bridging the gap between physical and chemical modifications. The research opens new avenues for the development and optimization of multifunctional devices in electronics and biomedical applications.</p>

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The adhesion and durability of model epoxy/silane/SiO2/Si bonded systems were investigated under various conditions, including the type of surface preparation, pH of the environmental media, temperature, cyclic thermal stress, and external applied stress. The fundamental debond mechanism was studied for bonded systems exposed to selected environments. The bond failure mode was characterized by examining the failed bond surfaces using X-ray photoelectron spectroscopy. The effectiveness of combining the oxygen plasma treatment and silane coupling agent (SCA) derivatization in adhesion promotion for an epoxy bonded to a silicon surface was evaluated in this research. SCAs with different amine functionalities were studied. The oxygen plasma treatment time was varied systematically to achieve a different extent of oxidation on the Si wafer. The surface chemistry/composition of various silane derivatized Si surfaces was investigated. The studies revealed that SCA interaction with the Si surface was enhanced by the oxygen plasma pre-treatment of the Si substrates. XPS surface analysis results showed that the SCA/SiO2 ratio did not correlate strongly with the increase in oxygen plasma pretreatment time. However, for Si surfaces treated for longer oxygen plasma pretreatment times, more silanol groups may be available to interact with the hydrolyzed silanol groups on silane, resulting in a stronger SCA-Si attachment. Three different tests were employed to determine adhesion and durability of the model epoxy/SCA/SiO2/Si bonded specimens. The immersion test qualitatively evaluates the bond durability for various systems exposed to different chemical and thermal conditions. Second, a novel probe test was used to quantitatively determine adhesion under critical debonding conditions for bonded specimens with different SCA preparations. A general trend of bond durability varied in the manner SCA-2 > SCA-3 > SCA-1 > no silane. Bond durability also increased for samples: model epoxy/SCA modified/O2 plasma treated/Si as the oxygen plasma pre-treatment time increased. Third, bond durability was studied using the wedge DCB (double cantilever beam) test under subcritical debonding conditions with environment-assisted crack growth as a function of applied strain energy release rate. Higher crack velocity and the absence of a Gthreshold value were noted in tests at 70 oC. The Gthreshold value increased as the strength of the interface increased and as the chemical aggressiveness of the environment decreased. For tests involving 25 oC -70 oC thermal cycling, only limited crack growth was found. / Ph. D.