Role of Capping Agent in Wet Synthesis of Nanoparticles

Abstract

Aqueous-based synthesis is one of the most popular methods to prepare nanoparticles. In these procedures, surfactants are needed to regulate the growth and final particle size. While there are numerous evidence on the decisive role of surfactants, a quantitative description remains elusive. This study develops a theoretical model to correlate the surfactant activities to particle growth. In the model, the "penetrability" of ions within surfactant layer is used to combine surface reaction and adsorption/desorption processes. The penetrability was then directly correlated to surfactant size. The theory was verified by synthesis of iron oxide nanoparticles with series of cationic surfactants. Eight surfactants, with same headgroup and increasing hydrocarbon tail, were employed. The experimental data showed a deterministic correlation between surfactant tails and particle size. The experimental correlation between surfactant length and particle size was predicted by the model. The modeling results verify the role of surfactant as capping agent during particle growth. More importantly, it provides a theoretical framework to control particle size in wet synthesis.

Modus Operandi of Simultaneous Covering Synthesis from Precursor Heterogeneity for Shelled Nanorods for Multipotent Cancer Theranostics

“…Therefore, recent research investigations have focused on synthetic strategies for distinct nanostructures, and on postsynthesis transformation prior to their functional application. However, all synthetic strategies are dominated by a thermodynamically controlled bottom‐up method using a reducing agent, and the use of a surfactant molecule capable of controlling the surface energy or physical dimension . In addition, to form a hollow or anisotropic structure, a secondary treatment such as a spontaneous redox reaction between the template and the replacement ions, as well as etching and calcination are required .…”

“…and the use of a surfactant molecule capable of controlling the surface energy or physical dimension. [21][22][23] In addition, to form a hollow or anisotropic structure, a secondary treatment such as a spontaneous redox reaction between the template and the replacement ions, [24][25][26] as well as etching [27][28][29] and calcination are required. [30,31] However, limitations such as reaction yield and reproducibility still remain.…”

Microwave‐assisted synthesis of water‐soluble styrylpyridine dye‐capped zinc oxide nanoparticles for antibacterial applications

“…The use of these water-soluble stabilizers or capping agents not only increases the lyophilic nature of the nanoparticles, but also electron injection can take place from the excited dye to conduction band of nanoparticles control of size, stability in solution, and necessary optical properties could be achieved. [29] Further research is necessary to use these functionalized nanomaterials in the biomedical field, it is also required to conduct a brief study to recognize the outcome of capping on these semiconductor oxide nanoparticles, before making a way into the biomedical field, these dye-capped semiconductor nanoparticles need to be tested for their toxicological actions against microorganisms and living systems. 201), and are in good agreement with the spherical and hexagonal wurtzite structure of bulk ZnO as confirmed by comparison with the JCPDS card (#36-1,451).…”

Effect of Particle Size on the Performance of TiO2 Based Dye‐Sensitized Solar Cells

“…It is well established that the properties of TiO 2 materials are highly dependent on its size, morphology, specific surface area, composition, crystallinity and porosity for various applications including DSSCs ,. Various types of capping agents including hetero‐atom‐functionalized long‐chain hydrocarbons, such as oleic acid (OA), oleylamine (OAm), octadecylamine (ODA),trioctylphosphine (TOP), triphenyl phosphine (TPP), dodecanethiol (DDA) etc, and polymers such as polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG), poly propylene glycol (PPG), polyacrylic acid (PAA), polyphenylene oxide (PPO), were used for controlling the size and achieving monodispersibility of nanoparticles . However, because of environmental friendly nature and easy removal processing after the synthesis step, polymers are usually more popular capping agents than the hetero‐atom‐functionalized long‐chain hydrocarbons.…”