Composites of conventional Ultra high molecular weight polyethylene (UHMWPE) and nanoparticles, such as carbon nanotubes or ceramics, require special processing techniques due to the high melt viscosity of the polymer matrix. Recently, we have shown that polymerisation with a single-site catalytic system in suitable reaction conditions produces “disentangled” UHMWPE that can be processed in the solid state. In this study, nanoparticles have been used as carriers for the single-site catalytic system in the polymerisation of UHMWPE. The high surface area of the nanoparticles, coupled with controlled reaction conditions, favours the growth of polyethylene chains with a reduced number of entanglements. This novel synthetic route offers several advantages: 1) the catalytic system is more stable and less fouling is observed during the polymerisation reaction; 2) nanoparticles are directly embedded in an otherwise intractable polymer matrix; 3) the low amount of entanglements in the UHMWPE matrix allows the resulting composites to be processed in the solid state well below the equilibrium melting temperature in a broad temperature window, to give high strength/high modulus tapes. These studies have been further extended where the polymerisation when performed in the presence of ethylene copolymers results into the homogeneous distribution of copolymers in the matrix of UHMWPE leading to unique morphologies during polymerization. References: Direct Route to Colloidal UHMWPE by Including LLDPE in Solution during Homogeneous Polymerization of Ethylene; S Ronca, G Forte, A Ailianou, JA Kornfield, S Rastogi; ACS Macro Letters 2012, 1, 1116-1120 Tailoring molecular structure via nanoparticles for solvent-free processing of ultra-high molecular weight polyethylene composites; S Ronca, G Forte, H Tjaden, Y Yao, S Rastogi; Polymer 2012, 53, 2897-2907