Morphological Control over ZnO Nanostructures from Self-Emulsion Polymerization

Abstract

Three different morphologies of ZnO nanostructures, such as nanospheres, nanorods, and nanoribbons, were controlled by tuning the ratio of the Zn2+ precursor to the 4VP monomer when polymerized in aqueous medium utilizing self-emulsion polymerization. The amphiphilic homopolymer (P4VP) acts as a template to form the ZnO/P4VP nanocomposite. The aspect ratio of the nanostructures is strongly dependent on the molar concentration of the Zn2+ precursor and becomes higher as its concentration increases. This results in different morphologies that are consistently repeatable. Pure ZnO was obtained from the ZnO/P4VP nanocomposites by calcination at 400 °C or by solvent washing. The calcination of the nanocomposties resulted in different morphologies, such as spherical, corolla shaped, and nanosheets. In addition, hexagonal nanoblocks, nanorods, and nanoribbons were observed when the polymer was removed from the nanocomposites by washing with chloroform. Removing polymer by solvent washing is a very easy, cost-effective method and has the potential for mass production of pure and highly crystalline ZnO nanostructures with known and controllable morphologies. The nanocomposites and pure ZnO nanostructures obtained after polymer removal were characterized by transmission electron microscopy, high resolution transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analyses, which confirmed the crystalline nature of the ZnO.

Size Stabilizers in Two-electrode Synthesis of ZnO Nanorods

“…This article reports further method development: we are testing four candidates for the size stabilizing precursors in a range of synthetic conditions. Hydrothermal syntheses of ZnO with the use of solvents [8], polymers [42][43][44], salicylic acid [45], amino acids [46] and surfactants [3] were reported earlier. Our current choice of stabilizers tested is not random.…”

In-Suspension Growth of ZnO Nanorods with Tunable Length and Diameter Using Polymorphic Seeds

“…However, although the growth of substrate-supported ZnO-NRs can be tuned by varying reaction time and precursor concentration, controlling the length of freestanding NRs is far more challenging. Indeed, the synthesis of shape- and length-controlled freestanding ZnO-NRs was demonstrated only with the assistance of surfactants or of coating polymers . Without the assistance of surfactants, only extremely long (several micrometers) and thick nanorods were obtained .…”

“…Indeed, the synthesis of shape-and length-controlled freestanding ZnO-NRs was demonstrated only with the assistance of surfactants 40 or of coating polymers. 41 Without the assistance of surfactants, only extremely long (several micrometers) and thick nanorods were obtained. 30 The seeded growth (SG) of ZnO-NRs by slow hydrolysis of Zn 2+ precursors has been successfully carried out in the past to prepare aligned NRs/NRs films on glass or a conductive glass substrate.…”

Self‐emulsion polymerization of amphiphilic monomers—a green route to synthesis of polymeric nanoscaffolds

“…We have shown that the polymer nanoparticles produced by SEP can be utilized as a template for the synthesis of various metal nanoparticles and semiconducting metal oxides. Using P4VP synthesized by SEP as a template, we have demonstrated the formation of ZnO nanoribbons, nanorods, and nanospheres . Recently, we reported a precise control of perovskite nanoparticle size embedded in a copolymer, poly(methyl methacrylate‐ co ‐4‐VP) synthesized via SEP …”