Block copolysiloxanes and their complexation with cobalt nanoparticles

Block copolysiloxanes have been prepared and utilized to form complexes of cobalt nanoparticles encased in the copolymers. The coated nanoparticles could be dispersed in polydimethylsiloxane (PDMS) to afford PDMS ferrofluids. imethylsiloxane-b-methylvinylsiloxane) (PDMS-b-PMVS) diblock copolymers were synthesized via anionic living polymerization with controlled molecular weights and narrow molecular weight distributions. The PMVS blocks were functionalized with trimethoxysilethyl or triethoxysilethyl pendent groups to yield poly(dimethylsiloxane-b-(methylvinyl-co-methyl(2-trimethoxysilethyl)siloxane) (PDMS-b-(PMVS-co-PMTMS)) or poly(dimethylsiloxane-b-(methylvinyl-co-methyl(2-triethoxysilethyl)siloxane) (PDMS-b-(PMVS-co-PMTES)) copolymers, respectively. suspensions of mostly superparamagnetic cobalt nanoparticles were prepared in toluene in the presence of PDMS-b-(PMVS-co-PMTMS) and PDMS-b-(PMVS-co-PMTES) copolymers via thermolysis of Co2(CO)8. TEM micrographs showed non-aggregated cobalt nanoparticles with mean particle diameters ranging from ≈10–15 nm. Specific saturation magnetizations of the cobalt–copolymer complexes ranged from ∼40–110 emu g−1 of cobalt.