Understanding Interfaces in OrganoSilicon Containing Coatings: Organosilane Adhesion Promoters

摘要

In the late 1940's it was shown that organosilanes could provide exceptional coupling or adhesive properties between an inorganic and organic phase. Subsequently, a wide range of coupling agents were developed that predominantly have the generic formula (RO)_3SiX. As the range of applications has grown, so has the complexity of the adhesion promoters used. Despite the increase in complexity the fundamental mechanisms of operation remain the same. In many markets, traditional materials are being replaced by thermoplastics, and as a consequence many modern technologies demand the ability to successfully adhere one polymer system to another. This is often achieved with the use of organosilane adhesion promoters. This study uses X-ray photoelectron spectroscopy (XPS) to investigate adsorption of organosilanes from solution onto poly(methylmethacrylate) (PMMA) and poly(ethylene terephthalate) (PET) substrates. The low surface energy of the thermoplastic substrate means that only small amounts of organosilane are adsorbed. Corona discharge treatment of the thermoplastic surface significantly changes the organosilane adsorption behaviour. Angle resolved XPS analysis showed that an adsorbed amino functional organosilane layer was orientated at the air interface, and the presence of a protonated amine at the polymer-silane interface was also demonstrated.