Functionalization of Silica Surface with UV-Active Molecules by Multivalent Organosilicon Spacer

Olga Iliashevsky,Elina Rubinov,Moshe Gottlieb,Yafa Yagen

doi:10.4236/ojic.2016.63012

Abstract

Immobilization of active molecules by attachment onto solid surfaces is a well-established practice in many processes and applications. Silica micro- and nano-particles are attractive candidates as support for active molecules as a result of a combination of desirable properties. The present study deals with grafting of a functional UV active molecule onto silica surfaces via hydrosilylation reactions using multivalent organosilicon spacers. Different types of organosilicon precursors based on dimethylsiloxysilanes containing multiple SiH groups were used as spacers between vinyl-modified silica surface and the benzotriazole UV-absorber (UVA). Firstly, the surface of silica was modified with vinyltrimetoxsisilane coupling agent. The UVA molecules were attached to the silica-vinyl by a two-step procedure involving hydrosilylation reaction. The successful grafting was confirmed by FTIR, TGA and UV-Vis characterization. More than fivefold increase in UVA loading was found for the MH30 multifunctional spacer, which contains approximately 75 SiH groups per molecule, when compared to a four-functional spacer. Furthermore a branched, bulky six-functional spacer is preferred over a linear spacer of the same functionality. UV activity of functionalized silica was studied by UV-Vis spectroscopy, indicating that the immobilization of UVA onto silica surface has not altered its UV absorbance properties.

Highlights

Immobilization of active molecules by attachment onto solid surfaces in order to prevent their loss, facilitateHow to cite this paper: Iliashevsky, O., Rubinov, E., Yagen, Y. and Gottlieb, M. (2016) Functionalization of Silica Surface with UV-Active Molecules by Multivalent Organosilicon Spacer
Different types of organosilicon precursors based on dimethylsiloxysilanes containing multiple SiH groups were used as spacers between vinyl-modified silica surface and the UV-absorber (UVA) molecules. 2-(2H-benzotriazol-2-yl)-4-methyl-6-(2-propenyl) phenol that belongs to the benzotriazole family, the most widely investigated and used group of UVA [13], was chosen as the UV active molecule due to its ability to undergo hydrosilylation reaction with SiH groups without the loss of UV-absorbing properties
UV active molecule has been successfully attached onto vinyl-modified silica surface using different types of multivalent organosilicon precursors, which were used as a spacer between vinyl-modified silica surface and the UV-absorber

Summary

Introduction

Immobilization of active molecules by attachment onto solid surfaces in order to prevent their loss, facilitateHow to cite this paper: Iliashevsky, O., Rubinov, E., Yagen, Y. and Gottlieb, M. (2016) Functionalization of Silica Surface with UV-Active Molecules by Multivalent Organosilicon Spacer. A number of desirable organic molecules are devoid of a reactive group suitable for covalent grafting onto the silica surface as in the case of organic UV absorbing molecules commonly used as light-stabilizers in polyolefins. Because of their relatively low molecular weight and thermodynamic incompatibility with the substrate, they are easy to volatilize during polymer processing or usage and they tend to migrate and bleed-out onto the article surface after relatively short times

Methods

Results

Conclusion