Formation of Silver Nanoparticles at the Air−Water Interface Mediated by a Monolayer of Functionalized Hyperbranched Molecules

Abstract

Nanofibrillar micellar structures formed by the amphiphilic hyperbranched molecules within a Langmuir monolayer were utilized as matter for silver nanoparticle formation from the ion-containing water subphase. We observed that silver nanoparticles were formed within the multifunctional amphiphilic hyperbranched molecules. The diameter of nanoparticles varied from 2-4 nm and was controlled by the core dimensions and the interfibrillar free surface area. Furthermore, upon addition of potassium nitrate to the subphase, the Langmuir monolayer templated the nanoparticles' formation along the nanofibrillar structures. The suggested mechanism of nanoparticle formation involves the oxidation of primary amino groups by silver catalysis facilitated by "caging" of silver ions within surface areas dominated by multibranched cores. This system provides an example of a one-step process in which hyperbranched molecules with outer alkyl tails and compressed amine-hydroxyl cores mediated the formation of stable nanoparticles placed along/among/beneath the nanofibrillar micelles.

Flexible and Robust 2D Arrays of Silver Nanowires Encapsulated within Freestanding Layer-by-Layer Films

“…The available forms of silver nanoparticles include spheres, [16] cubes, [17,18] rods, [19][20][21][22][23][24][25][26][27][28][29][30][31][32] tubes, [33] prisms, [34] dendrites, [35] plates, [36,37] cables, [38] and wires with diameters as low as 0.4 nm. [39] Among the different synthetic methods, [40] polyol synthesis, which was first introduced in 1989, [41][42][43] has been much exploited. [21,44,45] By changing the ratio between the poly(vinyl pyrrolidone) (PVP) capping agent and the silver nitrate precursor, silver nanoparticles can be obtained in various shapes.…”

Assembling hyperbranched polymerics

“…12,13 Other macromolecular architectures, such as star-shaped block copolymers, have been found to exhibit interesting aggregation behavior, [14][15][16][17][18][19][20][21] which can be used for a guided formation of fluorescent nanofibers and microfibers. 22,23 The multiple terminal groups are used to control the assembly of the molecules in solution, and at surfaces and interfaces [24][25][26][27][28][29][30][31][32] as well as their stimuli-responsive behavior. 33,34 Unique morphologies were found in branched and star block copolymers that are not observed for linear block copolymers.…”

“…[78][79][80][81][82] Relevant surface layers from dendrimers, which are popular, regular, highly branched polymers, have been fabricated and studied since mid-1990s. 23,[83][84][85][86][87] For instance, Xiao and coworkers have created thin films from SiCl 3 -terminated dendrons on mica. 88 Van Duijvenbode and coworkers fabricated surface layers from five generations of 1,4-diaminobutane poly(propylene imine).…”

Freestanding 2D Arrays of Silver Nanorods

“…Silver nanoparticles can be synthesized in the form of traditional nanospheres, [1] anisotropically shaped cubes, [2] rods, [3][4][5][6][7] tubes, [8] prisms, [9] dendrites, [10] plates, [11] disks, [12] and nanowires. [13] These silver nanoparticles can be exploited as nanoscale building blocks with unique properties, such as geometry-dependent optical properties [14,15] or surface-enhanced Raman scattering.…”