Facile synthesis of self-aligned gold nanoparticles by crack templated reduction lithography

Abstract

Fabrication of 1D gold nanoparticle (NP) arrays by crack templated reduction lithography (CTRL) isdemonstrated. The gold NPs are synthesized in situ on the cracks in a polydimethoxysiloxane (PDMS) substrate without additional reducing/stabilizing agents. Upon directionally bending the substrate, various array patterns formed on the PDMS rubber.Highly aligned gold nanoparticles (NPs) and nanowires (NWs) have attracted considerable interest owing to their diverse applications in electrical 1-4 and optical sensors. 5-7 Enormous efforts have been devoted to producing aligned gold NPs and NWs on a large scale. Electrodeposition of metal NWs in a conned region, such as anodized anodic membranes, and the synthesis of metal NPs by reducing agents are well-known conventional solution processes to prepare metal NWs and NPs.1,2,8-11 Although these approaches can produce large quantities, their applications are restricted when the NPs and NWs must be aligned on a solid surface because this alignment requires additional transfer processes. In situ synthesis methods on solid surfaces have also been investigated, including lithographically patterned electrodeposition, 12,13 microstructured template-guided methods, 14-16and biomolecule-templated methods.17-20 Currently, these approaches enable the preparation of selectively aligned NPs and NWs, but obtaining a highly aligned 1D array of NPs and NWs without using an additional nano-or microstructure patterned substrate is difficult. Hence, a simple route for the preparation of 1D arrays of NPs and NWs on solid surfaces is still required to achieve selective alignment, diverse patterns, and size control.Herein, we report a novel synthesis approach for 1D gold NP arrays based on regulated crack templated reduction lithography (CTRL) on a liquid PDMS surface. The selective aqueous synthesis of gold nanoparticles along the cracks on PDMS rubber has not been investigated thus far. In our experiments, liquid PDMS on an elastomer substrate is treated with oxygen plasma and stretched, resulting in the formation of a patterned crack in the stiff silica layer on the surface of the liquid PDMS. The native liquid PDMS was thereby exposed to the environment by cracking this silica layer covering the silicon oil. The uncovered regions of liquid PDMS were subsequently exposed to the gold precursor solution. The curing agent in the PDMS caused 1D gold NP arrays to spontaneously form along the crack on the liquid PDMS surface. Furthermore, we generated various patterns of gold NP arrays by manipulating the PDMS in various ways. Notably, we successively fabricated wide and narrow gold NP arrays by controlling the liquid PDMS thickness. Therefore, we were able to realize a novel approach for well-aligned gold nanoarrays, such as wires, based on cracking a stiff silica layer on PDMS rubber and using precursor chemistry. Gold NP arrays prepared by the developed approach may be utilized in optical and chemical sensing and stretchable electronics in the near future.The aligned crack patterns on th...

Direct Bottom-UpIn SituGrowth: A Paradigm Shift for Studies in Wet-Chemical Synthesis of Gold Nanoparticles

“…Solution nucleation of particles leads to consumption of the gold precursor and can produce polycrystalline structures that can later deposit onto the surface, increasing polydispersity of the final products. ,,, There are many materials on which direct growth of gold and other metal nanoparticles can be directly performed. A few examples include graphene/graphene oxide, , MoS 2 , , cellulose, , silicon, polydimethylsiloxane (PDMS), − polyelectrolyte multilayers, and conductive polymers polypyrrole and polyaniline …”

“…227,228 Directional deformation of the PDMS has been used to grow ∼100 nm particle arrays on 800 nm wide and 120 nm amplitude cracks. 227 Directional wrinkling gives a similar result, producing line arrays 400 nm wide and 30 nm deep (Figure 10C). 228 2.3.2.2.…”

Surface Lattice Plasmon Resonances by Direct In Situ Substrate Growth of Gold Nanoparticles in Ordered Arrays

“…[30,59,60] In fact, using only a surfacebound strong reductant usually requires ≈5 times more gold salt and hours to days long incubation. [31,32,35] Continuing with the goal of limiting secondary nucleation, we identified factors that could lead to the undesired spontaneous formation of colloids: i) the presence of impurities in the growth solution, ii) growth rate, and iii) excess ink leeching into solution. Regarding impurities, the water source is known to play important roles in colloidal synthesis, especially for the synthesis of anisotropic particles.…”

“…So far, the possibility to direct growth into tunable nanometric patterns has proven difficult to achieve via in situ growth. [31][32][33][34][35] Recent strategies for site-directed in situ gold nanoparticle growth include cracktemplated reduction lithography and similar methods. [32,35] Despite the possibility of creating single-nanoparticle-wide features using these techniques, the patterns accessible are limited to lines with resolutions of microns to hundreds of nanometers.…”

“…[31][32][33][34][35] Recent strategies for site-directed in situ gold nanoparticle growth include cracktemplated reduction lithography and similar methods. [32,35] Despite the possibility of creating single-nanoparticle-wide features using these techniques, the patterns accessible are limited to lines with resolutions of microns to hundreds of nanometers. Chemical patterning via microcontact printing has been combined with in situ growth to grow gold nanoparticles selectively on tunable micron-scale features, but with limited control over the nanoparticle morphology.…”