Synthesis and characterization of tunable and highly transparent thick layers of nanocomposites based on methacrylates and silica nanoparticles

We present a nanocomposite material based on functionalized silica nanoparticles in a methacrylate matrix. The nanocomposite material is synthesized without addition of a cosolvent, which enables the spin-coating of thick and defect-free layers of several tens of micrometers with smooth surfaces. SEM analysis indicates uniform distribution of the nanoparticles in the methacrylate matrix, and pinhole-free surfaces suitable for applications in optics. For optical characterization, the refractive index of the material for different silica concentrations is reported, and propagation losses in the UV/VIS range discussed. The tuning of the refractive indices can be applied towards the realization of low-loss passive optical waveguides. As a first step towards this goal, the processibility of the nanocomposite material for microfluidic applications, and the realization of a planar optical waveguide are demonstrated. © 2007 Materials Research Society.