Deuterium wide-line nuclear magnetic resonance and infrared time correlation function studies of the interfacial dynamics of bound alkyl chains

The current dissertation research involves the investigation of motional dynamics of alkyl modified silica in the dry state and in contact with various solvents. Both fast and intermediate molecular fluctuations are studied respectively by FT-IR and solid state NMR techniques. Both of these studies represent new experimental application of both techniques.; Wide-line {dollar}sp2{dollar}H NMR spectrometry has been used previously to probe the interfacial properties of alkyl modified silica. The current study uses the wide-line {dollar}sp2{dollar}H NMR technique to investigate the interfacial structure and ordering of 12-{dollar}sp2{dollar}H-dodecyl modified silica in dry state and in contact with various hydrocarbon solvents at low temperatures. The {dollar}sp2{dollar}H NMR line shapes of the immobilized dodecyl groups show dramatic changes in ordering with interfacial freezing.; Likewise, it has been well known that the Fourier transform of an infrared absorption band gives time correlation function of the vibrational transition moment. Most of the previous experimental investigations of the correlation function have only been confined to small molecules in the gas phase or in solution. In the current study, the Fourier transform technique is applied to analyze the infrared data of a more complex system such as 12-{dollar}sp2{dollar}H-dodecyl modified silica in dry state and in contact with various hydrocarbon solvents. This new method gives a useful information of molecular motion hindered by the anchoring of aliphatic chains on the surface of silica. In addition, it provides the basis for the application of FT-IR time correlations to material science problems.