Dwight Edward Williams

Sputter-Induced Compositional Change During ESCA/Sputtering of Polymers

The extent of sputter-induced elemental compositional changes (artifacts) in polymers was determined from ESCA band areas. A variety of organic and organo-silicone polymers was studied. Pristine surfaces of known, depth-invariant composition were prepared by vacuum fracture. Measured elemental calibration factors agreed well with literature values. Artifacts were evaluated by ESCA after various sputtering durations. The extent of the artifacts depended on the specific polymer and sputtering conditions. The artifacts were generally small or negligible for silicone polymers but were very large for the organic polymers and sputtering conditions used.

Methyl NMR chemical shift-structure correlations in cyclopolymethylphenylsiloxanes

Abstract The methyl 1 H NMR chemical shifts of various isomers of the title compounds are reported, as is the synthesis of several new compounds. A reliable correlation is shown between chemical shift and structure which is useful for structure confirmation. A statistical approach to isomer identification by use of these shift-structure correlations is given which often affords unambiguous identifications.