Switchable surfaces, also called smart surfaces or controllable surfaces, respond to changes in their local environment resulting in altered surface properties. There are various environmental perturbations that can cause changes to the surface properties but the focus of this thesis is on the affect of electrostatic potential. Significant evidence is provided from previous reports on electrochemical and infrared spectroscopic experiments suggesting that self-assembled monolayers (SAMs) of 4-mercaptobenzoic acid (4-MBA) undergo protonation-deprotonation by the application of an electric field. However, there are plenty of aspects of this electric field driven protonation-deprotonation mechanisms using carboxylic acid terminated SAMs that are not well understood. Most importantly, there is a lack of model independent measurements to validate this process. As such, experimental techniques utilizing infrared spectroscopy were employed to correlate electrochemical measurements and models.<p> This body of work demonstrates the importance of the intermolecular hydrogen bonding network on the measured voltammetric peak associated with the protonation-deprotonation of these SAMs. The voltammetric peak height diminishes with increasing exposure to an electrolyte solution. This behaviour is attributed to the replacement of the carboxylic acid protons with electrolyte cations and ultimately the disruption of the hydrogen bonded network.<p> We attempted to further our ex-situ infrared measurements by using an in-situ spectroelectrochemical technique. We had some initial successes, presented within, but more work is needed to complete this picture and is beyond the scope of this thesis. To summarize, the protonated state of SAMs of 4-MBA can be driven by the application of an electric field providing a potential platform to build a controllable smart surface.

As variation in pork tenderness has increased, identification of tenderness has become an industry need. This study consisted of 1208 pork loins randomly selected to test the efficacy of four automated grading techniques. Visible and near-infrared spectroscopy (VVNIR) (350-1830 nm wavelengths), bioelectrical impedance (EI) (resistance, reactance, phase angle, and partial capacitance), pH, and CIE L*, a* and b* color space values were used to predict chemical moisture and lipid, pH, Warner-Bratzler shear force (WBSF), and Slice shear force (SSF) on 13 d aged pork loins. The means and standard deviations for WBSF were (22.95 and 5.16) and SSF were (165.49 and 58.15). Prediction was based on stepwise linear regression and partial least squares regression. VNIR, pH, and color, when in combination, had the highest R^2 (0.19 and 0.21) for the prediction of WBSF and SSF, respectively. Partial least squares regression (PLSR) was used to remove autocorrelation between VNIR values. By using PLSR, with an R ^2 value of 0.49, 100 percent of the "tender" chops were correctly classified, 93 percent of the "intermediate" chops were correctly classified, and 92 percent of the "tough" chops were correctly classified into its category for WBSF. However, SSF was much lower (R^2 = 0.24) with only correctly placing 62 percent of the "tender" chops and only 48 percent of the "intermediate" and "tough" chops. Electrical impedance, alone or in combination with other technologies, either did not improve predictability of linear regression equations (increase R^2) or of PLSR models (increase R^2). Equations and models that included EI values had low R^2. When adding EI to the regression equation involving all variables, R^2 increased slightly from 0.19 to 0.21 in predicting WBSF, and from 0.21 to 0.25 for SSF. When pH or CIE L* color space values were included in linear regression or PLSR models to predict WBSF and SSF, R^2 values increased from 0.14 to 0.19 for WBSF, and 0.14 to 0.21 for SSF. pH played a large role in predicting WBSF and SSF, along with CIE L*. Thus, for an on-line situation, use of VNIR, pH, and color could be used to predict tenderness. Utilization of VNIR alone could be effective in predicting pork tenderness (WBSF). Using EI alone, or in combination with VNIR, would not provide acceptable prediction of WBSF or SSF. Use of VNIR with pH and color would improve the ability to predict tender and intermediate pork WBSF and SSF, but the additional improvement in accuracy may not be warranted based on the cost and additional time needed when using more than one technology.

Systems in which there are strong specific interactions between the polymer and CO₂ are of interest in a number of applications including polymer foaming, coating and impregnation. Unfortunately, experimental data on the phase behavior of such systems are relatively scarce, as are models that explicitly consider specific interactions in such systems. The overall goal of this work was therefore to develop a method for the measurement of specific interactions in polymer + CO₂ systems and to apply such measurements to the development of a thermodynamic model for polymer solutions. This work demonstrates that in situ ATR-FTIR spectroscopy may be used to quantify specific interactions in CO₂ + polymer- systems that incorporate carbonyl, ether, siloxane and sulfone groups. However, carbonyl stretching frequencies cannot be used to quantify such interactions between CO₂ and carbonyl polymers, contrary to what has been suggested in the literature. This is because blue shifts in the carbonyl stretching frequencies were observed in the ATR-FTIR spectra of CO₂ + PVAc, CO₂ + PMMA, CO₂ + PLA, and CO₂ + PLGA85 systems. These CO₂ induced blue shifts can be attributed to dielectric effects, and therefore cannot be used to quantify specific interactions in these systems. We propose the use of the temperature dependence of the CO₂ bending mode to quantify specific interactions in CO₂ + carbonyl polymers. With this method, the enthalpies of association for C=O...CO₂ specific interactions were found to be between -7 and -10 kJ/mol in the order: CO₂ + PVAc > CO₂ + PCL ≈ CO₂ + PLA > CO₂ + PLGA85 > CO₂ + PMMA. The method was also extended to other CO₂ philic polymers, leading to enthalpies of association in the order CO₂ + PEG > CO₂ + PVAc > CO₂ + PSF > CO₂ + PMSSQ >> CO₂ + PVDF&PS. Specific interactions in polymer + CO₂systems were also investigated via NVT molecular dynamics simulations Such interactions were found to decrease in the order: CO₂...C-O-C > CO₂...O=C-O > CO₂...Si-O-Si. In addition, the association distance was identified to be 3.2 Å. Finally, CO₂ accessibility was found to decrease in the order PVAc > PVMK > PLA > PMA. It was also confirmed that 96 % of associated CO₂ molecules interact with one carbonyl group in these systems. A ternary extension of the Compressible Lattice Model (CLM) was developed and the enthalpy of specific interactions obtained from ATR_FTIR spectra was incorporated into the model to correlate and predict phase behavior in polymer + CO₂ + cosolvent systems. This work shows that model parameters obtained from binary data can be used to predict ternary system behavior with average absolute deviations between calculated and experimental values (AAD) less than 10%. The Sanchez-Lacombe lattice-fluid partition function was extended to associated systems by incorporating an association factor obtained from the Compressible Lattice Model. The resulting Associated Sanchez-Lacombe (ASL) EOS has the same form as the SL EOS, but includes the effects of specific interaction in the calculation of lattice energies, and chemical potentials. We demonstrate that ASL model parameters obtained from correlation of sorption equilibria can be used to predict swelling of polymers with AAD less than 10%. In summary, specific interactions between CO₂ and C=O and other CO₂-philic groups have been quantified using in situ ATR-FTIR spectroscopy. The results have been directly incorporated into a lattice model that is able to correlate cloud points, and sorption equilibria, using a single parameter. The model is therefore likely to be beneficial in many applications involving polymer + CO₂ or polymer + CO₂ + cosolvent systems including polymer impregnation, coating, foaming, and polymer membranes for CO₂ capture. An EOS formulation for the model has been derived for the calculation of swelling in these systems.

The idea of terahertz-time-domain spectroscopy (THz-TDS) is to exploit a single cycle, spectrally broad THz radiation pulse to gain insight into the response of matter. Photoconductive devices and nonlinear crystals are utilized in both the generation as well as the coherent detection of THz radiation. The relatively high cost and the complexity of commonly used titanium-sapphire lasers hinder a more widespread use of pulsed THz systems for commercial applications. Er-doped femtosecond fiber lasers operating at 1.55 μm could offer a viable alternative. In this thesis nonlinear crystals and photoconductive emitters are discussed for excitation in the near infrared (NIR) window of between 800 nm to 1550 nm. The main focus of this thesis is a detailed study of substrate materials for an interdigitated photoconductive antenna. Photoconductive antennas with microstructured electrodes provide high electric acceleration fields at moderate voltages because of small electrode separations. The scalability of these devices allows for large active areas in the mm^2 range, which are sufficient for excitation at large optical powers. In comparison with conventional emitter structures, these antennas have more favourable characteristics regarding THz power, spectral properties, and ease of handling. Depending on the utilized substrate material, photoconductive antennas can then be operated using different excitation wavelengths. By employing substrates with short carrier trapping times these antennas can be operated as THz-detectors. Moreover the design of electrode structures for generating radially and azimuthally polarized THz waves are presented. A second topic deals with the signal analysis and signal interpretation of THz pulses transmitted through several material systems. These experiments show the potential for tomographic and spectroscopic applications. The third part deals with THz emission by frequency mixing in nonlinear organic and inorganic crystals. Hereby the focus is on polaritonic phase matching in GaAs. Furthermore, indications of THz tunability by the excitation wavelength were found by utilizing waveguide structures. However, the observed tuning range is much lower then theoretically predicted. Specific reasons for this are discussed.

Thesis (M.S.)--University of Hawaii at Manoa, 2005. / Includes bibliographical references (leaves 48-50). Also available via World Wide Web.

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains xiii, 187 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 171-175).

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph.D.) -- University of Texas at Arlington, 2007.

Thesis (Ph.D)--Chemical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Sujit Banerjee; Committee Co-Chair: Wm. James Frederick, Jr.; Committee Member: John D. Muzzy; Committee Member: Kristiina Iisa; Committee Member: Preet Singh. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (M.Ch.E.)--University of Delaware, 2009. / Principal faculty advisor: Jochen A. Lauterbach, Dept. of Chemical Engineering. Includes bibliographical references.