Covalent Polymer Chains on Siloxane-Functionalized Si Substrate

Concept (11-point bold, 0,5line space before and after) We show a platform for fabricating robust poly(methyl methacrylate) molecular architectures covalently bound to silylated Si(100) substrates, by an atom transfer radical polymerization approach. The chemical composition of these surface structures was investigated by X-ray photoelectron spectra, whereas the surface morphology studies were carried out by atomic force microscopy. The optical characterization by infrared attenuated total reflectance spectra have shown increasing poly(methyl methacrylate) signals upon increasing reaction time. These optical results, combined with the AFM lithography data, allowed us to monitor the growth of these hybrid inorganic/organic structures by detecting the thickness of the samples in a easy and accurate way. In our reaction conditions, the thickness of poly(methyl methacrylate) on Si(100) can be modulated in the nanometer range. Motivations and Objectives PMMA represents a key macromolecular component for dielectric low-k hybrid inorganic–organic polymer materials. It shows a refractive index that can be suitably modified by ion implantation, moreover, both the specular reflectivity and optical loss, due to diffuse reflectivity in Si implanted PMMA, are of practical interest for photonic applications. In addition, PMMA and polycarbonate are transparent thermoplastic polymers, often used as an alternative to glass. Since PMMA does not contain the harmful bisphenol-A subunit, present in polycarbonate, it is preferred for biological applications such as the fabrication of ocular lenses. Results and Discussion Figure 1 shows the IR-ATR spectra for representative Si(100)_PMMA samples at different reaction times :1 h (cyan), 2 h (orange), 5 h (green), 10 h (red) and 20 h (blue). The increase of both the 1731 ((C=O)) and 3000–2840 (n(CH2 and CH3)) cm-1 strong bands, with the reaction time, is strongly indicative of the increased PMMA amount on the Si(100) surface. In fact, a linear correlation of the increase in the MMA amount in the polymer chains (increase of polymerization degree) vs. the reaction time is observed in this range(Fig. 2)