Processing of flame-made nanoparticles into polymers is reviewed including surface modification and compounding. Recent advances in combustion and aerosol science enable scalable synthesis of such nanoparticles way beyond today's commercially available nanostructured carbon black and fumed silica. As a result, sophisticated filter nanoparticles with closely controlled size, morphology (aggregates or agglomerates) and composition (segregated or mixed phases or nanothin coatings onto core particles) become available motivating research for their surface functionalization and dispersion. Emphasis is placed on nanocomposite mechanics and optics. Quantitative relations for optimal. nanocomposite structure are presented: from the particle-polymer interface to the formation of a percolation network. (C) 2010 Elsevier Ltd. All rights reserved.