Picture of person typing on laptop with programming code visible on the laptop screen

World class computing and information science research at Strathclyde...

The Strathprints institutional repository is a digital archive of University of Strathclyde's Open Access research outputs. Strathprints provides access to thousands of Open Access research papers by University of Strathclyde researchers, including by researchers from the Department of Computer & Information Sciences involved in mathematically structured programming, similarity and metric search, computer security, software systems, combinatronics and digital health.

The Department also includes the iSchool Research Group, which performs leading research into socio-technical phenomena and topics such as information retrieval and information seeking behaviour.

Explore

Lewis acid mediated polymerization of poly(dimethylsiloxane) polymers : investigating reaction kinetics using both NMR spectroscopy and cyclic voltammetry

Apedaile, Alistair and Liggat, John and Parkinson, John and Nikiforidis, George and Berlouis, Leonard and Patel, Mogon (2012) Lewis acid mediated polymerization of poly(dimethylsiloxane) polymers : investigating reaction kinetics using both NMR spectroscopy and cyclic voltammetry. Journal of Applied Polymer Science, 123 (5). pp. 2601-2608. ISSN 0021-8995

Full text not available in this repository. Request a copy from the Strathclyde author

Abstract

Bulk condensation polymerization of (dimethylmethoxy)-m-carborane and (dichlorodimethyl)-silane occurs in the presence of an Mx+Clx Lewis acid catalyst. In the literature, FeCl3 is commonly used as the catalyst of choice but little is known about the activation energy and entropy of this polymerization. By monitoring using 1H-NMR the reaction of a methoxy-terminated poly(dimethylsiloxane) and (dichlorodimethyl)silane the rate determining step in the FeCl3 catalyzed system is determined. The activation energy was calculated to be +43.6 kJ mol-1 and the entropy of the reaction was also calculated. The calculated large entropy of reaction indicates that the transition step is highly ordered. The formation of the electrophile intermediate species in the first step of the reaction has also been investigated using cyclic voltammetry. To the cyclic voltammetry data Randles-Sevcik fits have been applied to the oxidation peaks to determine the diffusion coefficients for the oxidation of Fe2+ to Fe3+ . Also, the initial prediction of a reversible reaction Step 1 was shown to be incorrect as the normalized reduction peak maxima increase with scan rate, indicative of an electron transfer-chemical reaction mechanism.