Assembly from ultrasmall solution droplets follows a different dynamic from that of larger scales. Using an independently controlled microfluidic probe in an atomic force microscope, subfemtoliter aqueous droplets containing polymers produce well-defined features with dimensions as small as tens of nanometers. The initial shape of the droplet and the concentration of solute within the droplet play significant roles in the final assembly of polymers due to the ultrafast evaporation rate and spatial confinement by the small droplets. These effects are used to control the final molecular assembly in terms of feature geometry and distribution and packing of individual molecules within the features. This work introduces new means of control over molecular assembly, bringing us closer to programmable synthesis for chemistry and materials science. The outcomes pave the way for three-dimensional (3D) nanoprinting in additive manufacturing.

Historically, the integration of insulators with decreasing dielectric constants, k, has been critical in improving devices performance. Themost efficient approach to decrease k is by introducing porosity. Since porosity directly impacts theYoung'smodulus, the accurate determination of the mechanical properties of porous dielectrics is essential in enabling their implementation into state-of-the-art devices. Currently, nanoindentation is the technique of choice, but as technology relevant thicknesses of dielectrics keep decreasing, substrate effects are unavoidably encountered. These issues have so far been circumvented by measuring bulk materials instead of their thin-film counterparts. This approach is, however, less than ideal as physical properties can be size-dependent. Moreover, pores densification also occurs, potentially leading to overestimated Young's modulus values. In this paper, we define a novel protocol based on ultra-low load, quasi-static nanoindentation to measure mechanical properties of porous thin-films as a function of porosity (0-60%) and thickness (150-700 nm). We could isolate materials densification from substrate effect, and we demonstrated that the former can be accounted for, while the latter does not happen until indentation depths are remarkably higher than the traditionally accepted indentation limit of 10% of the film thickness. Consequently, extremely accurate mechanical characterization of porous low-k thin-films is now possible. (c) 2017 The Electrochemical Society. All rights reserved.

Direct writing methods are a generic and simple means to produce designed structures in three dimensions (3D). The printing is achieved by extruding printing materials through a nozzle, which provides a platform to deliver a wide range of materials. Although this method has been routinely used for 3D printing at macroscopic scales, miniaturization to micrometer and nanometer scales and building hierarchical structures at multidimensional scales represent new challenges in research and development. The current work addresses these challenges by combining the spatial precision of atomic force microscopy (AFM) and local delivery capability of microfluidics. Specialized AFM probes serve dual roles of a microscopy tip and a delivery tool, enabling the miniaturization of 3D printing via direct material delivery. Stacking grids of 20 μm periodicity were printed layer-by-layer covering 1 mm × 1 mm regions. The spatial fidelity was measured to be several nanometers, which is among the highest in 3D printing. The results clearly demonstrate the feasibility of achieving high precision 3D nanoprinting with nanometer feature size and accuracy with practical throughput and overall size. This work paves the way for advanced applications of 3D hierarchical nanostructures.

A novel water purification membrane has been prepared by layer-by-layer (LBL) assembly of tailored, core-shell star block copolymers. The star block copolymer consists of a hydrophobic polystyrene core (PS) and a plurality of charged hydrophilic arms (poly(N, N-dimethylaminoethyl methacrylate): PDMAEMA or polymethacrylic acid: PMAA). The high density of functional groups per unit volume of the PS-PDMAEMA and PS-PMAA star polymers enabled the formation of thin films with densely packed spherical morphologies, even with a low number of LBL cycles. The hydrophilic arms at the membrane surface helped mitigate membrane fouling, whereas the hydrophobic PS core suppressed undesirable swelling of the LBL-films in water, retaining good film durability. The star polymer films composed of 3.5 alternating layers of PS-PDMAEMA and PS-PMAA demonstrated an efficient nanofiltration capability of >98% rejection toward the small carcinogenic textile dye, Congo Red, with high water flux (ca. 40 LMH at 50 psi) at very low operation pressure. (C) 2015 Elsevier Ltd. All rights reserved.

Three-dimensional (3D) printing has been a very active area of research and development due to its capability to produce 3D objects by design. Miniaturization and improvement of spatial resolution are major challenges in current 3D printing technology development. This work reports advances in miniaturizing 3D printing to nanometer scale using scanning probe microscopy in conjunction with local material delivery. Using polyelectrolyte polymers and complexes, we have demonstrated the concept of layer-by-layer nanoprinting by design. Nanometer precision is achieved in all three dimensions, as well as in inter-layer registry. The approach enables production of designed functional 3D materials with nanometer resolution, and as such creates a platform for conducting scientific research in designed 3D nano-environments as well as enabling production of nanomaterials and scaffolds for photonics, devices, biomedicine and tissue engineering.

Correlating spatial chemical information with the morphology of closely packed nanostructures remains a challenge for the scientific community. For example, supramolecular self-assembly, which provides a powerful and low-cost way to create nanoscale patterns and engineered nanostructures, is not easily interrogated in real space via existing nondestructive techniques based on optics or electrons. A novel scanning probe technique called infrared photoinduced force microscopy (IR PiFM) directly measures the photoinduced polarizability of the sample in the near field by detecting the time-integrated force between the tip and the sample. By imaging at multiple IR wavelengths corresponding to absorption peaks of different chemical species, PiFM has demonstrated the ability to spatially map nm-scale patterns of the individual chemical components of two different types of self-assembled block copolymer films. With chemical-specific nanometer-scale imaging, PiFM provides a powerful new analytical method for deepening our understanding of nanomaterials.

A method of producing a bit-patterned media on a flexible substrate using a low-cost, hot nanoimprinting process is investigated. Using a topographic master with features as small as 40 nm, a flexible plastic substrate is patterned with high fidelity. Magnetic material is sputter-deposited onto the patterned substrate to produce a magnetic tape media with densities as high as 100 Gigadot/in(2). Magnetic recording characteristics of the coated bit-patterned tape is evaluated in an apparatus which slides a recording head on the media with a high-resolution positioning capability.

We investigate the effect of two different surface treatments on shallow nitrogen-vacancy (NV) centers in diamond. Short duration oxygen plasma exposure is found to damage near-surface NV centers, resulting in their disappearance in fluorescence images. Subsequent annealing creates large numbers of new NV centers, attributed to plasma-induced vacancy creation. By tracking individual NV centers during thermal oxidation, we show that oxidation at 550 °C results in modest improvement of spin coherence. Higher temperature oxidations correlate with gradual decline in spin coherence and eventual instability of NV centers before ultimate disappearance. This is indicative of a reduction of the NV-to-surface distance due to oxidative etching. Thermal oxidation can offer controlled access to near-surface NV spins at the nanometer scale, an important requirement for many applications of NV-based nanomagnetometry.

Magnetic nanoparticles (MNPs) provide a set of building blocks for constructing stimuli-responsive nanoscale materials with properties that are unique to this scale. The size and the composition of MNPs are tunable to meet the requirements for a range of applications including biosensors and data storage. Although many of these technologies would significantly benefit from the organization of nanoparticles into higher-order architectures, the precise placement and arrangement of nanoparticles over large areas of a surface remain a challenge. Herein, we demonstrate the viability of magnetic nanoparticles for patterned recording media utilizing a template-directed self-assembly process to afford well-defined nanostructures of magnetic nanoparticles and access these assemblies using magnetic force microscopy and a magnetic recording head. Photolithographically defined holes were utilized as templates to form assemblies of ferrimagnetic nanoparticle rings or pillars selectively over a large area (>1 cm(2)) in just 30 s. This approach is applicable to other nanoparticle systems as well and enables their high-throughput self-assembly for future advanced device fabrication.

In this talk I will describe a new carrier system for delivery of hydrophobic drugs. It is based on polymeric inclusion complexes formed by interaction of polymeric-drug conjugates (Poly-Drug) with polymeric cyclodextrins (Poly-CD). We have formed polymer-drug conjugates of Paclitaxel (PTX) with maleic anhydride copolymers. The PTX is linked to the backbone by a degradable ester bond. We also synthesized a maleic anhydride copolymer conjugated with betacyclodextrins (Poly-CD) where the CDs are also linked by degradable ester bonds to the backbone polymer. We then interacted the polymer-PTX with the polymer-CD to form an inclusion complex “nanogel”. PTX drug was efficiently released from this nanogel over many hours in in vitro tests. In this talk I will describe the synthesis and performance of this new drug delivery system.

In this chapter, the authors focus on two probe-based techniques-multiple harmonics atomic force microscopy (AFM) and nanoindentation-and compare them to surface acoustic wave spectroscopy (SAWS). Here, they present a comparison of experimental results from eight different low-κ dielectric samples that were analyzed for their mechanical properties with ultralow load nanoindentation, SAWS, and multiharmonics AFM analysis. Multiharmonic microscopy with AFM was performed with the HarmoniX routine on a Bruker Dimension Icon. In multiharmonic AFM the force applied by the cantilever is sufficient to slightly deform the sample surface to extract mechanical property information. Here, experimental measurements of mechanical properties from multiharmonic AFM are described and compared to those from nanoindentation and SAWS measurements. Improved determination of fundamental properties such as Young's modulus provides more refined input to predictive modeling.