Two dimensional (2D) semiconductors have attracted attention for a range of electronic applications, such as transparent, flexible field effect transistors and sensors owing to their good optical transparency and mechanical flexibility. Efforts to exploit 2D semiconductors in electronics are hampered, however, by the lack of efficient methods for their synthesis at levels of quality, uniformity, and reliability needed for practical applications. Here, as an alternative 2D semiconductor, we study single crystal Si nanomembranes (NMs), formed in large area sheets with precisely defined thicknesses ranging from 1.4 to 10 nm. These Si NMs exhibit electronic properties of two-dimensional quantum wells and offer exceptionally high optical transparency and low flexural rigidity. Deterministic assembly techniques allow integration of these materials into unusual device architectures, including field effect transistors with total thicknesses of less than 12 nm, for potential use in transparent, flexible, and stretchable forms of electronics.

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Attempts were made to prepare monodispersed electronic ink particles by a new procedure, in situ emulsifier-free emulsion polymerization. Highly monodispersed poly(methyl methacrylate-co-ethylene glycol dimethacrylate) electronic ink particles containing blue dyes and charge control additives (E-81) were successfully prepared both in aqueous medium and in a mixture of water and methanol by emulsifier-free emulsion polymerization. On increasing either the concentration of oil blue N or E-81, the particle size decreased initially but then increased in the absence of methanol, whereas particle size progressively increases in the presence of methanol. The addition of methanol in the polymerization also influences the polymerization kinetic and the charge density of electronic ink particles. The resulting electronic inks were found to be smooth on the surfaces and particle sizes were 300-700 nm with a coefficient of variation of 0.3%. Electrophoretic mobility of the resulting electronic ink was -2.08 to -5.28 × 10 -5 cm 2 /V‚s in the presence of charge control additives.

Polymeric particles ranging in diameter from 1 to 3.5 µm containing a black dye, Sudan black B, were prepared by dispersion polymerization in a methanol and water mixture. To control their electrophoretic mobility, a varying amount of charge control additives was added after first labeling them with a fluorescent moiety to trace their distribution by confocal laser microscopy. The particle size was found to be quite sensitive to both the change in polarity of the polymerization medium and the amount of polymeric stabilizer employed. At the same time, increasing the amount of charge control additives resulted in an increase in the particle size. On the other hand, the electrophoretic mobility exhibited a maximum or optimum point at ∼0.3 wt % of charge control additive. This is consistent with the fluorescence intensity profile obtained from the confocal laser measurement, which shows a decrease in the intensity of the particles with increasing concentration of charge control additives. The simple peak patterns in the cross-sectional profile obtained from the confocal laser measurement suggests that the charge control additives are mainly distributed inside of the particles.

Titanium dioxide inorganic core and polymer shell composite poly(methyl methacrylate-co-butylacrylate-co-methacrylic acid) [P(MMA-co-BA)-MAA] particles were prepared by emulsion copolymerization. Fourier transform IR (FTIR) spectroscopy was used to measure the content of MAA composite particles. Dynamic light scattering (DLS) characterized the composite particle size and size distribution. The field emission SEM (FE-SEM) results of the composite particles showed regular spherical shape and no bare TiO 2 was detected on the whole surface of the samples. The composite particles were produced, showing good spectral reflectance compared with bare TiO 2 . TGA results indicated the encapsulation efficiency and estimated density of composite particles. Encapsulation efficiency was up to 78.9% and the density ranged from 1.76 to 1.94 g/cm 3 . Estimated density of the composite particles is suitable to 1.73 g/cm 3 , due to density matching with suspending media.