Octa(propylglycidyl ether) polyhedral oligomeric silsesquioxane (OpePOSS) was employed as a nanocrosslinker of novolac resin to prepare the organic-inorganic networks. The crosslinking reaction was investigated by means of Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopy via model reaction. Thermal analyses indicate that the glass transition temperatures (T-g's) and thermal stability of the organic-in organic networks increased with increasing the content of POSS. Contact angle measurements show that the organic-inorganic nanocomposites displayed a significant enhancement in surface hydrophobicity as well as reduction in surface free energy. The improvement in surface properties was ascribed to the presence of POSS moiety in place of polar component of phenolic thermosets. (c) 2007 Elsevier Ltd. All rights reserved.