A novel method for preparing silver/poly(siloxane-b-methyl methacrylate) (Ag/(PDMS-b-PMMA)) hybrid nanocomposites was proposed by using the siloxane-containing block copolymers as stabilizer. The reduction of silver nitrate (AgNO3) was performed in the mixture solvent of dimethyl formamide (DMF) and toluene, which was used to dissolve double-hydrophobic copolymer, as well as served as the powerful reductant. The presence of the PMMA block in the copolymer indeed exerted as capping ligands for nanoparticles. The resultant nanocomposites exhibited super hydrophobicity with water contact angle of 123.3(degrees) and the thermogravimetry analysis (TGA) revealed that the resultant nanocomposites with more PDMS were more heat-resisting. Besides, the antimicrobial efficiency of the most desirable nanocomposite (Ag/PDMS65-b-PMMA(30) loaded with 7.3% silver nanoparticle) could reach up to 99.4% when contacting with escherichia coli within 120 min. As a whole, the resultant nanocomposites by the integration of excellent properties of silver nanoparticles as well as siloxane-block copolymers can be a promising for the development of materials with hydrophobic, heat-resisting and outstanding antibacterial properties from the chemical product engineering viewpoint. (c) 2013 American Institute of Chemical Engineers AIChE J, 59: 4780-4793, 2013