19 January 2006 Characterisation of porous silicon/poly(L-lactide) composites prepared using surface initiated ring opening polymerisation
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Abstract
Inorganic/organic hybrid or composite materials have in the past shown novel and interesting properties, which are not observed for the individual components. In this context, the preparation of inorganic/polymeric composites from biodegradable and biocompatible constituents is a new concept, which may be of interest particularly for tissue engineering and drug delivery applications. We describe here the synthesis of nanostructured porous silicon (pSi) and poly(L-lactide) (PLLA) composites. The composites were produced using tin(II) 2-ethylhexanoate catalysed surface initiated ring opening polymerisation of L-lactide onto silanised porous silicon films and microparticles. The subsequent chemical, physiochemical and morphological characterisation was performed using Diffuse Reflectance Infrared Spectroscopy (DRIFTS), X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM), Differential Scanning Calorimetery (DSC), Thermogravimetric Analysis (TGA) and Contact Angle measurements. DRIFT spectra of the composites showed the presence of bands corresponding to ester carbonyl stretching vibrations as well as hydrocarbon stretching vibrations. XPS analysis confirmed that a layer of PLLA had been grafted onto pSi judging by the low Si content (ca. 3%) and O/C ratio close to that found for PLLA homopolymers. Comparison of the sessile drop contact angle produced by silanised pSi and PLLA grafted onto pSi showed an increase of ca. 40°. This is comparable to the increase in contact angle seen between blank silicon and spin-coated PLLA of ca. 44°. The AFM surface roughness after surface initiated polymerisation increased significantly and AFM images showed the formation of PLLA nanobrushes.
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Steven McInnes, Helmut Thissen, Namita Roy Choudhury, Nicolas H. Voelcker, "Characterisation of porous silicon/poly(L-lactide) composites prepared using surface initiated ring opening polymerisation", Proc. SPIE 6036, BioMEMS and Nanotechnology II, 60361X (19 January 2006); doi: 10.1117/12.659973; https://doi.org/10.1117/12.659973
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