Cobalt Nanoparticle Formation in the Pores of Hyper-Cross-Linked Polystyrene:  Control of Nanoparticle Growth and Morphology

Abstract

Impregnation of hyper-cross-linked polystyrene (HPS) by either Co 2 (CO) 8 in 2-propanol or the [Co(DMF) 6 ] 2+ [Co(CO) 4 ] -2 complex in dimethylformamide (DMF), followed by thermolysis at 200 °C, results in the formation of discrete Co nanoparticles. The concentration and characteristics of such nanoparticles were investigated by X-ray fluorescence (XRF) spectroscopy, ferromagnetic resonance (FMR) spectroscopy, and transmission electron microscopy (TEM). The FMR data here confirm the formation of spherical nanoparticles. At relatively low concentrations of Co, the magnitude of the FMR line width reveals that the mean Co nanoparticle diameter is about 2 nm, which agrees closely with the mean particle diameter discerned by TEM. An increase in Co content higher than 8 wt % is accompanied by an increase in mean particle diameter due to an increase in the population of large Co nanoparticles up to 15 nm across. Regulated nanoparticle growth over a wide range of Co concentrations is attributed to nanoscale HPS cavities, which serve to physically restrict the size of growing particles.

Influence of the Mesoporous Polymer Matrix Nature on the Formation of Catalytically Active Ruthenium Nanoparticles

“…This material can act as a nanostructured matrix which governs the metal particle growth. As we demonstrated earlier, HPS perfectly controls the formation of Co- [34], Pt- [35,36], Pd- [37] and Ru-NPs [38]. These NPs showed excellent activity and selectivity in the reaction of fine organic synthesis.…”

Nanostructured Polymeric Nanoreactors for Metal Nanoparticle Formation

“…The subsequent thermolysis at 200°C results in the formation of Co nanoparticles, the loading and characteristics of which were investigated by X-ray fluorescence (XRF) spectroscopy, FMR spectroscopy, and transmission electron microscopy (TEM). The FMR data presented in Figure 4.3 and Table 4.2 confirmed the formation of spherical nanoparticles [19]. A 2-8 wt.…”

“…HPS is able to swell in a wide variety of different solvents, even thermodynamically poor ones (e.g., water) that facilitate incorporation of various organometallic compounds into the nanostructured HPS matrix. The first use of HPS as a medium for Co nanoparticle formation was reported by us in 1999 [19]. Cobalt nanoparticles have been selected due to the established correlation between size and shape of Co particles and their mag- (Table 4.2).…”

Hybrid metal–polymer composites from functional block copolymers

“…Built on the foundations of coordination, organometallic, and nanocluster chemistry, where specific ligand chemistry influences the stability, oxidation state, and favored aggregation state of metallic species, ligand-functional polymers and block copolymers have been reported in many examples to specifically influence the nano-and mesoscale arrangement of inorganic species. [63][64][65] Furthermore, block copolymer self-assembly provides the potential for the ordered assembly and stabilization of nanoscale metallic objects. 18,42,44,66,67 In what are often called nanoreactor approaches to polymer-nanoparticle composites, metals can be chelated to polymers in solution before self-assembly in bulk [Scheme 2(A)] or the bulk polymer film can be treated with metallic species after self-assembly [Scheme 2(B)].…”