New liquid triarylamine-siloxane hybrid materials are produced using the Piers-Rubinsztajn reaction. Under mild conditions, liquid analogues of conventional and commonly crystalline triarylamines are easily synthesized from readily available or accessible intermediates. Using a diverse selection of triarylamines, we explored the effects of siloxane group and substitution pattern on the physical properties of these materials, and we have demonstrated that relatively large molecular liquids with desirable electrochemical properties can be produced. The interactions between the strongly Lewis acidic catalyst used for this transformation, tris(pentafluorophenyl)borane (BCF), and the Lewis basic triarylamine substrates were studied. Through UV-vis-NIR and (19)F NMR spectroscopy, we have proposed that the catalyst undergoes a reversible redox reaction with the substrates to produce a charge transfer complex. The formation of this charge transfer complex is sensitive to the oxidation potential of the triarylamine and can greatly affect the kinetics of the Piers-Rubinsztajn reaction.

The use of Piers−Rubinsztajn conditions was explored for the synthesis of silicone polymers bearing pendant triarylamine functionality. We have found that up to 60% of the hydride groups of a silicone copolymer can be successfully substituted with a triarylamine moiety, without metathesis or redistribution of the silicone. The resulting polymers are hydrolytically stable. The functionalization procedure is straightforward, conducted under ambient conditions with a simple one-step work-up, and avoids the use of a metal-based catalyst. The resulting phenylated triarylamine−silicone hybrid polymer was characterized by optical absorption and fluorescence spectroscopy, CV, and differential scanning calorimetry. The hybrids maintain the physical appearance of a silicone polymer while adopting the photophysical and electrochemical characteristics of the triarylamine.

Summary: In this paper we show how the strong organic Lewis acid catalyst, tris(pentafluorophenyl)borane (B(C6F5) or BCF), can be used to facilitate the functionalization of simple polymeric silicones with a triarylamine yielding a novel class of charge transporting materials. The reaction conditions we refer to as Piers‐Rubinsztajn Conditions and we have previously shown such conditions to be suitable when using phenylated silicones as precursors. In this work we found they also work successfully for a silicone oligomer as well as cocopolymers of polymethylhydridosiloxane (PMHS) and polydimethylsiloxane (PDMS) and a PMHS homopolymer, all of which are highly abundent and available in industrial quanitities. The resulting material was either a waxy solid, viscous oil or a glass. An additional “finishing” step with anisole using the same chemistry was found necessary to prevent gelation of the copolymer and homopolymer of PMHS. Even after finishing a small fraction (<5%) of Si‐H groups remained in the silicones. This nonetheless provides a rapid and mild method to synthesize functional silicones and tune their physical properties, using commonly available starting materials.

This presentation will cover a number of experiments undertaken by the author in the Loock Group  (Department of Chemistry, Queen’s University), which contributed to an ongoing research project to  develop a field deployable water sensor for monitoring of pollutants in ground water. The author’s investigations involved collaboration with graduate students and scientists from three Chemistry research  groups, using apparatus and instrumentation such as a refractometer for measuring the refractive index of  polymer mixtures under different ambient conditions; long­period gratings (LPGs) ‘written into’ optical fibre (125 &#956;m diameter); an optical spectrum analyser; a dip­coating machine; as well as scanning  electron microscope images of optical fibre samples. The focus of this research was the development and  characterization of coatings that increase the sensitivity of the sensor head. Results and conclusions from tests of different polymer coatings on LPGs and coated as films on silica wafers, responding to different organic compounds, will be presented. The author’s experiences and insights gained in the process of  scientific inquiry will also be discussed