INELASTIC ELECTRON TUNNELLING SPECTROSCOPY (lETS) OF SILANE COUPLING AGENTS

Inelastic Electron Tunnelling Spectroscopy (lETS) has been used to study monolayers of silane coupling agents adsorbed on aluminium oxide. The technique of lETS is surface specific and uses electrons to excite vibrational modes of the adsorbate. Since the tunnelling electrons perturb both the dipole moments and polarizability ellipsoids of the molecules both infra-red (IR) and Raman vibrations appear in an lET spectrum. Thus, spectral interpretation is simplified by the use of standard assignment tables. Silanes are used to improve the adhesion between an inorganic substrate and coating, the latter usually being a polymeric matrix. To fulfil this function the silane has dual functionality; usually two or three hydrolysable groups and a reactive end group compatible with the coating to be used. Here, mainly trialkoxysilanes have been studied with either vinyl, amine or epoxide end groups in order to identify the silane-substrate interactions and the final orientation of the adsorbed silane. The lETS results suggested that the surface interaction was strongly dependant on the method of doping the silane onto the surface. For the aluminium oxide used here trialkoxysilanes were found to interact in two ways, either by forming primary Si-O-Al bonds or by a covalent/donation type of bond. It was also found that both the amine and epoxide end groups also reacted with the surface rendering them unavailable for reaction with the coating. In order to substantiate the lETS results additional work using Static Secondary Ion Mass Spectrometry (SSIMS) and X-ray Photoelectron Spectroscopy (XPS) was also performed. Both these techniques gave complimentary results to lETS, supporting the proposed surface interactions and in addition enabled the aluminium oxide to be characterised. This allowed the lETS oxide to be usefully compared with an aluminium oxide prepared by a method as used in industry.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

1987

Author dc:creator

• WERRETT, CLIVE RUSSELL

Licence

• https://dora.dmu.ac.uk/bitstreams/46f4d311-6583-4c3f-974d-16b78f6b03c1/download