Selective self‐limited interaction of metal precursors with self‐assembled block copolymer substrates, combined with the unique molecular‐level management of reactions enabled by the atomic layer deposition process, is presented as a promising controllable way to synthesize patterned nanomaterials (e.g., Al2O3 see Figure, TiO2, etc.) with uniform and tunable dimensions.

Sequential infiltration synthesis (SIS), combining stepwise molecular assembly reactions with self-assembled block copolymer (BCP) substrates, provides a new strategy to pattern nanoscopic materials in a controllable way. The selective reaction of a metal precursor with one of the pristine BCP domains is the key step in the SIS process. Here we present a straightforward strategy to selectively modify self-assembled polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) BCP thin films to enable the SIS of a variety of materials including SiO(2), ZnO, and W. The selective and controlled interaction of trimethyl aluminum with carbonyl groups in the PMMA polymer domains generates Al-CH(3)/Al-OH sites inside the BCP scaffold which can seed the subsequent growth of a diverse range of materials without requiring complex block copolymer design and synthesis.

We introduced a method to obtain the continuum description of the elastic properties of monolayer h-BN through ab initio density functional theory. This thermodynamically rigorous continuum description of the elastic response is formulated by expanding the elastic strain energy density in a Taylor series in strain truncated after the fifth-order term. we obtained a total of fourteen nonzero independent elastic constants for the up to tenth-order tensor. We predicted the pressure dependent second-order elastic moduli. This continuum formulation is suitable for incorporation into the finite element method.

Hybrid organic-inorganic polymer thin films of the form (-O-Zn-O-C 2 H 4 -) n have been deposited from diethyl zinc and ethylene glycol using molecular layer deposition (MLD) over a range of substrate temperatures between 100 and 170 °C. Infrared transmission confirms that the films consist of Zn-O and ethylene-oxide units. In analogy with known alucone polymers of the form (-O-Al-O-R-) n , the zinc-based hybrid material is an example of a "zincone" polymer. In situ quartz crystal microbalance analysis indicated that the sequential surface reactions of diethyl zinc and ethylene glycol are sufficiently self-limiting and saturating to enable well-controlled MLD growth. Quantitative analysis of in situ quartz crystal microbalance and film thickness results indicate that ethylene glycol molecules can undergo a "double reaction" where the OH groups on both ends of the diol react with available Zn-C 2 H 5 surface sites to produce a relatively inert bridging alkane. The mass uptake per MLD cycle during Zn-hybrid film deposition decreases with increasing reaction temperature. Infrared transmission spectroscopy also shows that Zn-organic hybrid films are stable in dry air. However, the as-deposited ZnO-hybrid material could be hydrolyzed by H 2 O (for example, in ambient) resulting in films consisting of zinc oxide and zinc hydroxide with some carbon remnants. Spectroscopic ellipsometry indicates the thickness of hydrolyzed films increases linearly with reaction cycles, and scanning probe and transmission electron microscopy images show the hydrolyzed ZnO-hybrid film coating is uniform and conformal. The transmission electron micrographs also show the hydrolyzed Zn-hybrid films contain nanoscale porosity. These results suggest new pathways to fabricate organic-inorganic hybrid materials, including metalorganic framework structures.

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INTRODUCTIONSelf-assembly of block copolymer (BCP) thin films has been explored extensively as a strategy to make periodic nanostructures. 1À4 Because these nanoscale features can be formed reproducibly and at low-cost, there is tremendous interest in transferring such patterns to functional materials. In particular, BCP films are promising for microelectronics and data storage applications where highly dense and periodic nanoscale patterns are needed over a large area. 5À8 BCP films can self-organize to form nanostructures of various morphologies with tunable length scales. Furthermore, by guiding BCP self-assembly using surface topography, highly regular patterns can be generated over macroscopic area with low defect density. 9,10 Since BCP films with a single layer of laterally ordered domains have a thickness on the order of the domain size, they are generally too thin for transferring patterns into the underlying substrate using plasma etching. Because carbon-based polymer blocks erode quickly in a plasma, the masking BCP film is completely removed before features with significant depth can be transferred. For example, polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA), one of the most widely studied BCPs (including in lithography experiments), has an overall poor etch resistance, and the etch contrast between the blocks is only about two. 11 As a result, the depth that can be etched is only on the order of the thickness of the film at best, which is tens of nanometers in most cases. Significant effort has been invested in developing BCPs containing etch-resistant blocks such as polystyrene-block-polydimethylsiloxane (PS-b-PDMS) 12,13 or polystyrene-block-poly(ferrocenylsilane) (PS-b-PFS), 14À17 but many of these BCPs have poor wetting properties or are difficult to remove after the etching process. The synthesis of these polymers can also be challenging. Furthermore, organometallic blocks (such as PFS) are undesirable for microelectronics manufacturing, a major potential application of BCPs, because the uncontrolled diffusion of metals in a semiconductor can degrade the performance of microelectronic devices.For the reasons stated above, a BCP that is easy to synthesize, applicable over large areas, and resistant to plasma etching remains elusive. To etch high aspect-ratio structures, a common scheme is to first transfer the BCP pattern to an intermediate hard mask layer that provides greater etch resistance. The insertion of a hard mask layer adds complexity and cost to the fabrication process due to complications from stress and adhesion as well as the risk of damaging the underlying substrate during deposition. The interfacial interaction between the hard mask and the BCP may also change dramatically how the BCP self-assembles. Furthermore, transferring the pattern with high fidelity into the hard mask layer still requires etch contrast between the polymer blocks. Consequently, strong etch contrast between the BCP blocks is highly desired, regardless of the overall pattern transfer scheme.In this ...

Plenty of new two-dimensional materials including graphyne, graphdiyne, graphone, and graphane have been proposed and unveiled after the discovery of the “wonder material” graphene. Graphyne and graphdiyne are two-dimensional carbon allotropes of graphene with honeycomb structures. Graphone and graphane are hydrogenated derivatives of graphene. The advanced and unique properties of these new materials make them highly promising for applications in next generation nanoelectronics. Here, we briefly review their properties, including structural, mechanical, physical, and chemical properties, as well as their synthesis and applications in nanotechnology. Graphyne is better than graphene in directional electronic properties and charge carriers. With a band gap and magnetism, graphone and graphane show important applications in nanoelectronics and spintronics. Because these materials are close to graphene and will play important roles in carbon-based electronic devices, they deserve further, careful, and thorough studies for nanotechnology applications.

Atomic layer deposition (ALD) of Al2O3 on electrospun poly(vinyl alcohol) microfiber templates is demonstrated as an effective and robust strategy by which to fabricate long and uniform metal-oxide microtubes. The wall thickness is shown to be precisely controlled within a molecular layer or so by adjusting the number of ALD cycles utilized. By judicious selection of the electrospinning and ALD parameters, designer tubes of various sizes and inorganic materials can be synthesized.