The double-hydrophobic well-defined polydimethylsiloxane-block-poly(methyl methacrylate) (PDMS-b-PMMA) diblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Their chemical compositions and the structure were investigated. The micellization behavior of the double-hydrophobic diblock copolymers with equal block length was thoroughly studied. The results showed that their self-assembly behavior was analogous to the star-like micelles. Furthermore, the effect of temperature on the aggregates was investigated to verify that the resulting copolymer (PDMS-b-PMMA) was to some extent temperature sensitive. Till date, there have been few reports on the utilization of nonamphiphilic block copolymers to synthesize and confine metal nanoparticles in aggregates. In this study, we explored the role of double-hydrophobic block copolymers as a mediator for organically dispersible silver nanoparticles (AgNPs) and it offered to be an effective stabilizer for preparing AgNPs. Besides, AgNPs generated in organic solvent is an important addition to the hitherto predominantly water-based processes for producing nanoparticles inside the polymer surfactant. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers