Patterning Nanoparticles

To integrate nanoparticles in functional devices, other approaches based on dewetting, exploiting the spontaneous agglomeration in stripes, have been proposed (see also chapter 15). 

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Table 3 Summary of block copolymers studied for patterning nanoparticle applications... 

Figure 6.11 (a) Scheme of patterning nanoparticle thin films and (b) scanning electron... 

Figure 13.11 The patterning of nanoparticle crystals by combination of photolithography and surface wettability.75 A concentrated nanoparticle solution slowly evaporated in the gaps between the patterned substrate and a glass substrate. When the structure was peeled off, patterned nanoparticle crystals on both surfaces were formed.

There are two iCP methodologies for the assembly of nanoparticles into patterned nanoparticle arrays on surfaces (1) the direct use of nanoparticles as the ink in xCP and thus the transfer of the nanoparticle ink to the substrate by the stamp, and (2) the preparation of patterned monolayers on a substrate to direct the adsorption of nanoparticles from solution. Whitesides and coworkers pioneered... 

Figure 14.23 SEM micrographs of patterned nanoparticles discs at different magnifications. Concentration of nanoparticles = 1.0 mM molding pressure = 3.0 N cm [images taken from Ref 100].

The SECM studies of nanoparticles are of great interest and diversity. Metal nanoparticles can serve as redox mediators in solution to investigate their redox activities at solid-liquid and liquid-liquid interfaces by using SECM as discussed in Chapter 3. By contrast, this section is focused on the SECM studies of monolayers and multilayers of metal nanoparticles formed at various interfaces. In these studies, SECM was employed to quantitatively investigate the lateral conductivity and interfacial electroactivity of nanoparticle films. In addition, new experimental setups were developed to address the electrocatalytic and photocatalytic activities of nanoparticle films. Moreover, significant progresses were made to deposit and pattern nanoparticles on various substrates by using SECM. 

The silver nanoparticles were then spin-coated onto the patterned substrate followed by removal of the NIL template in acetone to yield sub-lOOnm patterns. Nanoparticles of ITO have been successfully patterned for use as a transparent conducting oxide. The patterned ITO was reported to have increased transparency at 485 nm wavelength of light when compared to ordinary ITO. 

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