Formation of gold nanoparticles in triblock terpolymer-modified inverse microemulsions

Abstract

The influence of polystyrene (PS)-block–poly(1,4-butadiene) (PB)-block–poly(ethylene oxide) (PEO) and poly(1,4-butadiene)-block–polystyrene-block–poly(ethylene oxide) triblock terpolymers on the phase behaviour of the w/o microemulsion of the pseudo-ternary system made of water/sodium dodecylsulfate (SDS)/xylene–pentanol (1:1) was investigated by varying the sequence of the blocks. Independent on the terpolymer used an enlargement of L2 phase can be observed with increasing polymer concentration. Simultaneously, a decrease of the diameter of the mixed inverse terpolymer-surfactant micelles can be observed by dynamic light scattering. After cross-linking of the butadiene units, covalently closed nanocapsules with an average size between 20 and 30 nm can be observed. When the triblock terpolymer-modified microemulsion is used as a template for the nanoparticle formation, gold nanoparticles with diameters of about 10 nm are formed. After solvent evaporation, the terpolymer-modified, hydrophobic gold nanoparticles can be redispersed in a toluene–pentanol mixture, and eliminated from the non-soluble surfactant residue.