Janus spheres, micron-sized silica spheres half-coated with platinum, move rectilinearly away from the platinum side in aqueous hydrogen peroxide. Upon self-assembling, these colloidal particles can form dimers with different conformations that exhibit both rectilinear and rotational modes of motion depending upon the relative orientation of each Janus sphere. At the micron length-scale, stochastic rotational Brownian dynamics is of the order of deterministic dynamics, and their coupling results in effective diffusion, in addition to passive translational diffusion. For dimers with rotary motion, the dynamic coupling leads to spiral trajectories for an ensemble average of the displacement vector.

Highly flexible, durable aerogels with textile feel were developed at Aspen Aerogels Inc. by sol-gel chemistry and supercritical CO2 solvent extraction. These polyisocyanate-based aerogels reinforced with battings showed little to no brittle fracture with repeated flexing. The crosslinker, the isocyanate content and functionality played an important role on properties such as thermal conductivity, durability and flexural modulus at ambient and cryogenic temperatures. The polyisocyanate aerogels crosslinked with polyamine showed thermal conductivities as low as 18 mW/m-K at ambient pressure and those crosslinked with polyol had low flexural modulus at cryogenic temperatures. Applications of these aerogels in aerospace and diving are presented.

Copper-alumina and copper-silica aerogels formed by impregnation of a copper(II) salt into an alumina or silica wet gel before supercritical extraction have been found to contain copper in multiple oxidation states: Cu0, Cu+1 and Cu+2. These aerogels are effective at catalyzing the reduction of NO and the oxidation of HCs and CO under conditions similar to those found in automotive three way catalysts. In this work we have developed a preparation method incorporating Cu0, Cu+1 and Cu+2 nanoparticles directly into silica aerogels. Nanoparticles in the form of (a) Cu0 nanorods (100 nm diameter, 10-20 μm length); (b) Cu+1 nanoparticles (350 nm diameter); and (c) Cu+2 nanoparticles (25-55 nm diameter) were added (0.5-15% by weight) to separate precursor mixtures consisting of tetramethyl orthosilicate, methanol, water and ammonia. These precursor mixtures were then processed using a rapid supercritical extraction (RSCE) method to form aerogels. The resulting aerogels show evidence of nanoparticles dispersed throughout the silica aerogel structure. Addition of Cu+1 and Cu+2 nanoparticles decreases the surface area of the aerogels significantly. X-Ray diffraction shows that regardless of initial oxidation state of the nanoparticles, crystalline Cu0 is detected after RSCE processing to 290 °C. Following heat treatment at 700 °C, crystalline Cu+2 is detected. The copper containing silica aerogels are found to be catalytically active with light-off temperatures (50% conversion) for NO and CO at 400 °C in three-way catalytic applications.

This comparative study on two interdisciplinary artistic practices aims to improve public perception of scientific research and to facilitate informed decision making regarding climate change and how it affects everyday life. It also hopes to break down (or bridge?) the isolated silos of Art and Science, by emphasizing the role of imagination as a tool of creation and innovation in the new economies of the 21st century. Notwithstanding the ephemeral appearance of the super-light nanomaterial silica aerogel used by Ioannis Michaloudis (Michalous) in his sculptures, the longevity of some of his art seems guaranteed: two works, Bottled Nymph and Noli Me Tangere have been selected to be rocketed to the moon as part of the MoonArk sculpture. The sculptures will be aboard a Space X Falcon 9 rocket launched in 2018 from Cape Kennedy in an Astrobotic Robotic Lunar Mission, and will remain on the moon, potentially, for billions of years. Spirited Skies is a project where we experience by touching other forms of longevity of the ephemeral silica aerogel. Filling double jacketed borosilicate glass vials with aerogel skies and clouds in a unique way, Michaloudis transforms every day’s life trivial objects into art. And whilst Michaloudis is seeding the heavens and landing his artwork onto the moon, a Masters student under his supervision, Matthew van Roden is waxing and waning back here on earth. Van Roden’s material of choice is wax, which he pushes through various artistic disciplines to extrapolate its flesh like qualities.

Au/TiO2 lyogels have been prepared by sol-gel process followed by freeze-drying and calcination in order to induce crystallization. In the synthesis, a dispersion of AuNPs was added either during the sol-gel process or mixed with the lyogels in a ball mill after the freeze-drying. The lyogels are formed of TiO2 crystallites decorated with Au nanoparticles. The size of the TiO2 crystallites and the proportion of anatase and rutile depend on the parameters of the calcinations. The efficiency in photocatalysis diminishes with the size of the crystallites and is optimal when the lyogels include rutile together with the photoactive anatase.

Magnesium oxide aerogels were made by sol-gel process using magnesium methoxide as precursor, methanol and deionized water as solvent with ethanol supercritical fluid drying. The influences of the different factors on the gel time and the specific surface area of magnesium oxide aerogels were studied, and the structure and morphology were characterized by Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and X-ray diffraction (XRD), and the Small Angle X-ray Scatter (SAXS) was utilized to determine the fractural structure of the magnesium oxide aerogels. The results show that MgO aerogels belong to the typical mesoporous materials with rich network and highly developed pore structure, and the specific surface area is 904.9 m2/g, the apparent density is 0.055 g/cm3, the average pore size is 19.6 nm. The results of SAXS analysis show that the fractal dimension of the MgO aerogels is 2.32 in high q area which proves the existence of rough surface and pore fractal structure.

Silica aerogels are unique lightweight, nanostructured materials with extremely high porosity (usually above 90%), making them particularly attractive for thermal insulation, although their mechanical fragility still requires strategies of reinforcement that may compromise some of their most appealing properties. The use of silica aerogels still needs to be matured for a broad range of other high-performance applications, and even improved for insulation application. This can be achieved by intensely exploring their surface chemistry versatility, by relying on the enormous variety of silane precursors and chemical routes that can be used. In this work, we present two examples of using reactive moieties in the silane precursors for the preparation of silica aerogels for multipurpose application. In the first case, an acrylate containing silane (3-(trimethoxysilyl)propyl methacrylate) is used along with tetramethyl orthosilicate to produce an organically-modified silica network, which could be reinforced by adding 1,6-bis(trimethoxysilyl)hexane or 1,4-bis(triethoxysilyl)-benzene as spacers and tris[2-(acryloyloxy)ethyl] isocyanurate as cross-linker. These hybrid aerogels have shown an interesting combination of thermal insulation and mechanical properties. Moreover, they could be chemically doped with silica-functionalized magnetite nanoparticles imparting magnetic behaviour to the aerogels but also improving their thermal insulation performance and mechanical strength. Their magnetic feature can be useful for several applications including magnetic separation and drug delivery. As a second example, amine and thiol-functionalized aerogels were used as adsorbents to capture heavy metals from wastewater by complexation, and the preparation of these materials could be accomplished using a combination of silanes, including hydrophobic moieties for a compromise to ensure material stability and good adsorption capacities. Removal percentages of heavy metals reaching 90% were found for metal concentrations of environmental relevance. The amine functionality in aerogels is also useful for other purposes, for example to improve the rate capability of silica aerogels to remove carbon dioxide from gaseous streams or environments.

Aerogels are a promising material for aerospace applications and have recently been explored for biomedical applications also. In both environments, exposure to radiation is inevitable, such as from radiation in space or, radiation-based sterilization and tracking of implants. X-ray radiation, in particular, is of a concern. Here, polyurea-crosslinked silica aerogel (PCSA) samples were exposed to approximately 170- and 500-Gy X-irradiation at room temperature under varying environmental conditions and characterized using electron spin resonance (ESR) technique. Results obtained for PCSA were compared with those from polyether-ether ketone (PEEK) and ultra-high molecular weight polyethylene (UHMWPE) which served as benchmarks for this study. PEEK is known to be very radiation resistant, while UHMWPE is known to be less radiation resistant. All materials (PCSA, PEEK, and UHMWPE) were exposed to the same treatments and exposure conditions. Two exposure times were tested: 10 min and 30 min which corresponded to “low” and “high” conditions, as well as comparisons of nitrogen vs. air environments during exposure and post-exposure storage. Results showed significant quantities of free radicals produced in PCSA after exposure to X-irradiation which scaled with radiation dosage; quantities were in-between those produced in PEEK and UHMWPE. The storage conditions (air vs. nitrogen) also played an important role in the free radical levels detected and are reported in this study.

The interaction of laser radiation with low density aerogels is of crucial importance in areas such as the creation of coherent radiation sources in the X-ray range, simulation of astrophysical as well as nuclear fusion phenomena in laboratory and fundamental studies of the properties of soft condensed matter under dynamic pressure in the Mbar range. In the present paper, the experimental results on the X-ray emission of laser induced plasma in TEOS based, MTMS based aerogels and solid quartz targets, are reported. The aerogels were produced by the sol-gel processing of tetraethoxysilane (TEOS) and methyltrimethoxysilane (MTMS) followed by supercritical drying. Silica alcogels were produced using 0.001 M oxalic acid (C2H4O4), 0.5 M ammonium hydroxide (NH4OH) catalysts. Different densities of aerogels varying from 0.02 to 0.06 g/cm3 have been obtained using different molar ratios of TEOS, MTMS, ethanol and catalysts. The laser, with intensity up to 2 x 1014 W/m2, interaction with TEOS and MTMS based aerogels have been conducted using 30J/500 ps Nd : glass laser system. The resulting soft (0.8 – 1.56 Kev) and hard (>4 Kev) X-ray emissions have been measured using semiconductor photodiodes. It has been observed that the soft X-ray yield increases by a factor of two for the silica aerogel targets compared to the X-ray emission from the solid quartz target, whereas the hard X-ray yield reduces. The enhanced soft X-ray yield in silica aerogel targets is attributed to the large volume heating.

Determining what external stimuli influence cell differentiation, morphology, and growth continues to be a focus on many research groups to meet the healthcare Grand Challenges. While prior work has shown the influence of stiffness, surface chemistry and topography, these parameters often change in tandem, making it difficult to delineate the role of an individual component. This study examined the possible incorporation of microelectronic processing to produce reusable substrates for cell guidance studies. Subsequent plating of substrates cleaned with methods common in a microelectronic fabrication process showed complex responses including migration. Optical characterization of surfaces after cleaning showed remaining cellular debris that could be removed through the incorporation of a piranha solution. The micro patterned substrates did allow controlled comparison between dental pulp stem cells and osteoblast cells. The dental pulp cells did not show any cell alignment or cell proliferation (as indicated by cell density) with the isotropic or anisotropic micropatterns on the initial plating. The osteoblast cells (control) only aligned with the lines and not any of the other patterns (dots, holes or hexagons).

Polymer nanocomposites (PNC) include a copolymer or polymer which has nanoparticles dispersed in the polymer matrix at the nano-level. One of the most common types of polymer nanocomposites contain smectic clays as the nanoparticles. These clay minerals increase the mechanical properties of standard polymers and improve barrier properties. For optimum barrier properties, Layer-by-Layer assembly (LbL) is one of the most effective methods for depositing thin films. LbL methods however, are quite tedious and produce large quantities of waste. A newly discovered phenomenon of self-assembled polymer nanocomposites utilizes entropic forces to drive the assembly to spontaneously form a larger nanostructured film. This approach allows polymers and nanoparticles with high particle loadings to be mixed, and create the super gas barrier films. We have developed a coating technique which can be employed to make self-assembled gas barrier films via inkjet printing. This technique is industrially scalable and efficient. This is because it does not need any rinsing step and drying steps as required in LbL. The influence of different polymers Polyvinylpyrrolidone (PVP) and Poly (acrylic acid) PAA with Montmorillonite (MMT) nanoclay solutions on Polyethylene terephthalate (PET) substrate is examined to study their effectiveness as a gas barrier film. The results showing the excellent oxygen barrier behavior of a combination of PVP and MMT Nano clay nanocomposite with high transparency. These high barrier gas nanocomposite films are good candidates for a variety of food packaging applications.

Stabilization of surface supported fluid lipid multilayers for underwater characterization is an essential step in making them useful for scalable cell culture applications such as high throughput screening. To this end, we used tetraethyl orthosilicate (TEOS), recently shown to stabilize fluid lipid films while maintaining their fluidity and functionality under water, to stabilize lipid multilayer micropatterns of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). The treated multilayers were immersed under water and successfully imaged by atomic force microscopy (AFM), a difficult feat to perform on fluid lipid multilayers without TEOS treatment. The treated lipid multilayer showed an average swelling of approximately 18% in water but remained stable during the imaging process. The TEOS-treated lipid multilayers also proved compatible with cell culture as HeLa, MDCK, and HEK cell types all adhered and grew in high numbers over the multilayers. The results obtained here open the door to the use of fluid lipid multilayers in biotechnology applications such as microarray based high throughput cell assays.