ABSTRACT
Inelastic neutron scattering spectra of the polydimethylsiloxane polymer models, methyltrichlorosilane (MTCS), dimethyldichlorosilane (DMDCS), trimethylchlorosilane (TMCS), hexamethyldisiloxane (HMDS), and octamethyltrisiloxane (OMTS), are reported and assigned by comparison with ab initio calculations. Also reported are the spectra of a series of polydimethylsiloxane samples with viscosities in the range 5-100 cSt, based on the model compounds and calculated spectra of a short polydimethylsiloxane, and the spectrum of polydimethylsiloxane is reassigned. Also reported are the infrared (IR) and Raman spectra of TMCS and OMTS.
Subject(s)
Chlorine Compounds/chemistry , Dimethylpolysiloxanes/chemistry , Models, Chemical , Models, Molecular , Neutron Diffraction/methods , Silanes/chemistry , Silicones/chemistry , Spectrum Analysis/methods , Computer Simulation , VibrationABSTRACT
An inelastic neutron scattering spectrum of a poly(dimethylsiloxane) (PDMS) is reported, and a spectrum simulated using a monomer molecular unit as a model for comparison. FT-Raman spectra of a series of PDMS derivatives are reported and structure spectra correlations are shown to exist for the estimation of (a) PDMS average chain length, (b) ratio of the number of monofunctional units to quadrifunctional units in silicone resins, and (c) the percentage weight of PDMS in silicone emulsions.
ABSTRACT
The potential use of resonance Raman spectroscopy as a molecular sensing tool is illustrated using a metalloporphyrin template and pyridine as an analyte. The equilibrium binding constant for the axial binding of pyridine to zinc tetraphenylporphyrin has been measured using resonance Raman spectroscopy. Although no new peaks are observed and the porphyrin peaks do not shift position, the quantification is made possible by the selective resonance enhancement of the template vibrations. The value for log k was determined by resonance Raman to be 3.65 +/- 0.32, which compares well with previously published values estimated using absorption data. Values for log k were determined for a series of related compounds, the picolines, and these also compare favourably with those previously reported.
