Amphiphilic Poly(organosiloxane) Nanospheres as Nanoreactors for the Synthesis of Topologically Trapped Gold, Silver, and Palladium Colloids

Abstract

Amphiphilic poly(organosiloxane) nanospheres with different core-shell architectures are employed as passive nanoreactors for the synthesis of noble metal colloids. The amphiphilic poly-(organosiloxane) nanospheres, which have diameters between 15 and 40 nm, possess a hydrophilic interior and a hydrophobic shell. Dispersed in organic solvents such as toluene, it has been achieved to transfer hydrophilic noble metal salts through the solvent into the nanospheres by either liquid-liquid or solidliquid phase transfer. Subsequently, reduction of the noble metal salt with lithium triethylborohydride led to the formation of 2-5 nm sized noble metal colloids. If the network density of the shell of the poly-(organosiloxane) nanospheres is small enough, the colloids are topologically trapped inside the nanospheres and stabilized against aggregation. By employing hydrogen tetrachloroaurate(III), silver nitrate, or palladium(II) chloride, it was possible to synthesize topologically trapped gold, silver, or palladium colloids, respectively. The number, the size, and the stability of the colloids depend mainly on (i) the kind of phase transfer chosen, (ii) the amount of hydrophilic groups in the poly(organosiloxane) nanospheres, and (iii) the architecture of the poly(organosiloxane) nanospheres.

Self-Assembled Nanoreactors

“…Jungmann et al have prepared hollow amphiphilic poly(organosiloxane) nanospheres by sequential condensation of silanes and have used them as nanoreactors for the synthesis of Ag, Au, and Pd nanoparticles ( Figure 29). 273 After the hollow poly(organosiloxane) nanospheres were loaded with salts of the noble metals, reduction was performed with LiBEt 3 H, resulting in the formation of 2-5 nm size metal colloids.…”

Multifunctional, multicompartment polyorganosiloxane magnetic nanoparticles for biomedical applications

“…The particles have been characterized by AF-FFF, TEM, SQUID and Mö ssbauer spectroscopy. As shown previously, the polyorganosiloxane nanospheres can be used as nanocontainers and nanoreactors [9,16], allowing potential incorporation of different functionalities in the future. In addition, the surface of the polyorganosiloxane can be modified by grafting with, for example, poly(ethylene oxide) to make the nanospheres water dispersable.…”

Physics and Chemistry of Sol-Gel Nanocomposites Formation

“…Moreover, amphiphile polyorganosiloxanes (hydrophilic inner part and hydrophobic shell) can be themselves stabilizing agents (specific nanoreactors) for nanoparticles, for example, noble metals [115]. Polysilane shell cross-linked by PMMA is a polymer micelle stabilizing Au nanoparticles (average diameter 25 nm) and Pd (20 nm), the latter has effective catalytic activity in Heck reaction [116].…”