National Nanomanufacturing Network

Natural nanocrystals shown to strengthen concrete

National Nanomanufacturing Network - April 2, 2015 - 11:07am
Cellulose nanocrystals derived from industrial byproducts have been shown to increase the strength of concrete, representing a potential renewable additive to improve the ubiquitous construction material. The cellulose nanocrystals (CNCs) could be refined from byproducts generated in the paper, bioenergy, agriculture and pulp industries. They are extracted from structures called cellulose microfibrils, which help to give plants and trees their high strength, lightweight and resilience. Now, researchers at Purdue University have demonstrated that the cellulose nanocrystals can increase the tensile strength of concrete by 30 percent. "This is an abundant, renewable material that can be harvested from low-quality cellulose feedstocks already being produced in various industrial processes," said Pablo Zavattieri (http://engineering.purdue.edu/~zavattie), an associate professor in the Lyles School of Civil Engineering (https://engineering.purdue.edu/CE). The cellulose nanocrystals might be used to create a new class of biomaterials with wide-ranging applications, such as strengthening construction materials and automotive components. Research findings were published in February in the journal Cement and Concrete Composites. The work was conducted by Jason Weiss (https://engineering.purdue.edu/CE/People/view_person?resource_id=2284), Purdue's Jack and Kay Hockema Professor of Civil Engineering and director of the Pankow Materials Laboratory (https://engineering.purdue.edu/~concrete/weiss/index.html); Robert J. Moon (http://www.fpl.fs.fed.us/people/bios/employee_level_bio.php?employee_id=185), a researcher from the U.S. Forest Service's Forest Products Laboratory; Jeffrey Youngblood (https://engineering.purdue.edu/MSE/People/ptProfile?id=11541), an associate professor of materials engineering; doctoral student Yizheng Cao; and Zavattieri. One factor limiting the strength and durability of today's concrete is that not all of the cement particles are hydrated after being mixed, leaving pores and defects that hamper strength and durability. "So, in essence, we are not using 100 percent of the cement," Zavattieri said. However, the researchers have discovered that the cellulose nanocrystals increase the hydration of the concrete mixture, allowing more of it to cure and potentially altering the structure of concrete and strengthening it. As a result, less concrete needs to be used. The cellulose nanocrystals are about 3 to 20 nanometers wide by 50-500 nanometers long - or about 1/1,000th the width of a grain of sand - making them too small to study with light microscopes and difficult to measure with laboratory instruments. They come from a variety of biological sources, primarily trees and plants. The concrete was studied using several analytical and imaging techniques. Because chemical reactions in concrete hardening are exothermic, some of the tests measured the amount of heat released, indicating an increase in hydration of the concrete. The researchers also hypothesized the precise location of the nanocrystals in the cement matrix and learned how they interact with cement particles in both fresh and hardened concrete. The nanocrystals were shown to form little inlets for water to better penetrate the concrete. The research dovetails with the goals of P3Nano (http://www.usendowment.org/p3nano.html), a public-private partnership supporting development and use of wood-based nanomaterial for a wide-range of commercial products. "The idea is to support and help Purdue further advance the CNC-Cement technology for full-scale field trials and the potential for commercialization," Zavattieri said. This research was funded by the National Science Foundation. Reference: The influence of cellulose nanocrystal additions on the performance of cement paste (http://dx.doi.org/10.1016/j.cemconcomp.2014.11.008), Yizheng Cao, Pablo Zavaterri, Jeff Youngblood, Robert Moon, Jason Weiss. Cement and Concrete Composites, Volume 56, February 2015, Pages 73–83 Source: Purdue University News (https://www.purdue.edu/newsroom/releases/2015/Q1/natural-nanocrystals-shown-to-strengthen-concrete-.html)

Nanomanufacturing: Building a Community of Practice

National Nanomanufacturing Network - March 27, 2015 - 4:58am
Establishment of a sustainable nanomanufacturing ecosystem faces numerous challenges due to the inherent nature of nanotechnology, which intersects multiple industries, involves multidisciplinary scientific researchers, while encompassing an extensive range of highly unique technologies including materials, processes, and equipment. As such, building a community of practice entails a broad range of activities from standards, education and workforce development, technology roadmaps, best practices, informatics, environmental health and safety, to commercialization. To ensure progress on all of these fronts, community involvement is essential for providing broad perspectives from a range of stakeholders in industry, government, and academia in order to better understand where fundamental and applied research intersects emerging and established regulatory and commercialization activities and roadmaps. While these issues may be relatively clear cut for specific segments of nanotechnology commercialization, it is not always clear where best practices translate to adjacent application and industry roadmaps. An important activity for building the nanomanufacturing community of practice is thematic workshops involving a group of experts and practitioners in the field. To this end, the NNN has sponsored several thematic workshops since inception including collaborative workshops with NSF (2008 Research Challenges for Integrated SystemsNanomanufacturing (http://eprints.internano.org/49/)), NNIN (2010 Synergies in Nanoscale Manufacturingand Research (http://eprints.internano.org/2230/)), NIST (2012 Nanofabrication Technologies forRoll-to-Roll Processes (http://eprints.internano.org/1842/)), and a series of workshops on Nanoinformatics (2007-present). The essence of these workshops is to incorporate different viewpoints on topics relevant to the workshop theme in order to better understand methods, challenges, emerging R D, and gaps in research activities towards addressing the associated challenges. The NNN has strived to enhance these workshops by convening a balance of industry, academic, and government participants which, when combined with topical questionnaires distributed prior to the workshop assist in focusing the content of the presentations, discussions, and breakout sessions thereby enabling a productive event with measurable outcomes. Typical work products for these workshops include reports, roadmaps, publications, collaborations amongst participants, proposals, and broader initiatives or funding opportunities. With the goal of contributing towards the establishment of a nanomanufacturing roadmap, as well as formulating a NNN 2.0 initiative, the NNN solicits comments, suggestions and ideas for future topical workshops in nanomanufacturing from our members and stakeholders. Along with suggestions for topics and subtopics, further details including suggested experts and participants, relevant gaps and questions to be addressed in the workshop with respect to the nanomanufacturing enterprise. These activities are an essential component of the NNN and it is critical to our mission that we consider these activities with input from the community as a whole, as well as reach out to the relevant stakeholders, industry and government agencies having significant stake in the topic of interest to obtain their contributions or involvement. We look forward to receiving ideas and suggestions for potential workshops, and will provide feedback in the future in order to prioritize the topics.

EPA proposes reporting and record keeping requirements on nanomaterials

National Nanomanufacturing Network - March 27, 2015 - 3:58am
For the first time the agency will use TSCA authority to collect health and safety information on nanoscale chemicals already in use The U.S. Environmental Protection Agency (EPA) is proposing one-time reporting and recordkeeping requirements on nanoscale chemical substances in the marketplace. Nanotechnology holds great promise for improving products, from TVs and vehicles to batteries and solar panels,” said Jim Jones, EPA’s Assistant Administrator for Chemical Safety and Pollution Prevention. “We want to continue to facilitate the trend toward this important technology. Today’s action will ensure that EPA also has information on nano-sized versions of chemicals that are already in the marketplace.” EPA currently reviews new chemical substances manufactured or processed as nanomaterials prior to introduction into the marketplace to ensure that they are safe. For the first time, the agency is proposing to use TSCA to collect existing exposure and health and safety information on chemicals currently in the marketplace when manufactured or processed as nanoscale materials. The proposal will require one-time reporting from companies that manufacture or process chemical substances as nanoscale materials. The companies will notify EPA of: certain information, including specific chemical identity; production volume; methods of manufacture; processing, use, exposure, and release information; and, available health and safety data. Nanoscale materials have special properties related to their small size such as greater strength and lighter weight, however, they may take on different properties than their conventionally-sized counterpart. The proposal is not intended to conclude that nanoscale materials will cause harm to human health or the environment; Rather, EPA would use the information gathered to determine if any further action under the Toxic Substances Control Act (TSCA), including additional information collection, is needed. The proposed reporting requirements are being issued under the authority of section 8(a) under TSCA. The agency is requesting public comment on the proposed reporting and recordkeeping requirements 90 days from publication in the Federal Register. EPA also anticipates holding a public meeting during the comment period. The time and place of the meeting will be announced on EPA’s web page at: http://www.epa.gov/oppt/nano/ (http://www.epa.gov/oppt/nano/) Additional information and a fact sheet on the specifics of the proposed rule and what constitutes a nanoscale chemical material can be found at: http://www.epa.gov/oppt/nano/ (http://www.epa.gov/oppt/nano/) Source: EPA (http://yosemite.epa.gov/opa/admpress.nsf/d0cf6618525a9efb85257359003fb69d/36465ec76a3b4efd85257e13004e8c95!opendocument)

National Nanotechnology Initiative publishes report assessing the status of EHS risk science

National Nanomanufacturing Network - March 27, 2015 - 3:38am
The National Nanotechnology Initiative (NNI) today published the report from the workshop, “Stakeholder Perspectives on Perception, Assessment,and Management of the Potential Risks of Nanotechnology” (R3 Workshop), which was held September 10-11, 2013, in Washington, D.C. The goal of the workshop was to assess the status of nanotechnology environmental, health, and safety (EHS) risk science three years after the development of the 2011 NNI EHS Research Strategy and to identify the tools and best practices used by risk assessors to address the implications of nanotechnology. A wide range of stakeholders including Federal and State regulators, small and large businesses, insurance companies, academic researchers, occupational safety specialists, and public and environmental advocacy groups shared their perspectives on the risk management process; discussed strategies and approaches for improving risk science methods; and examined ways that NNI agencies can assist stakeholders in the image002.jpgresponsible development of nanotechnology. Stakeholders participating in the workshop presented their perspectives and methods used to assess and manage the potential risks of nanotechnology. Research presented at the workshop shows that technical risk data alone will not enable decisions; risk evaluations by different stakeholders with varying biases, values, and stances can affect the perceptions and behaviors (e.g., investment or personal safety decisions) of consumers, regulators, developers, manufacturers, and insurers. Following a robust dialogue among participants, including a variety of stakeholder perspectives, participants identified needs in four areas. (The following list is not prioritized): Communication Resources, including improved transparency in reporting the presence of engineered nanomaterials (ENMs) and continued collaboration among diverse stakeholder groups.Decision Tools, such as improved detection and characterization tools; improved methods for assessing both actual exposure to and potential risk from ENMs; tools to address nanotechnology-related environmental, health, and safety (“nanoEHS”) issues sooner in the product life cycle.Data Resources, such as repositories or databases to facilitate access to or organization of existing information on nanoEHS; methods for accessing and investigating potentially protected information; and continued toxicology studies on the effects of ENMs.Standards and Guidance Resources, in order to facilitate navigation of nanotechnology-enabled applications through the regulatory process and improved data quality and methods for reporting data used in nanomaterial risk assessment. You can download full document from the InterNano Library (http://eprints.internano.org/2229/) Source: National Nanotechnology Initiative (http://www.nano.gov/node/1350)

Solar Cells with Tunable Colors

National Nanomanufacturing Network - March 26, 2015 - 5:27am
With rising levels of atmospheric carbon dioxide and indicators for global climate change increasingly apparent, the search has intensified for more sustainable and renewable alternative energy sources. Photovoltaic (PV) energy has been of interest for the last 40 years; however, the cost of Si-based solar panels is still not cost-effective for widespread usage. In addition to the overall cost, consumer adoption of this technology has been slow due to the unattractive aesthetics of traditional solar panels. Building integrated photovoltaics (BIPVs) such as Dow PowerhouseTM Solar Shingles have reached the market, but have not yet been widely adopted. In order for PV technology to be widely accepted, it will need to be seamlessly incorporated into existing infrastructures such as building and automotive materials, and be available in a variety of colors. Among the various types of emerging PV technologies such as dye-sensitized solar cells (DSSCs), organic cells, and quantum dots (QDs), perovskite solar cells represent one of the most promising sectors. In a span of only 5 years, the efficiency of perovskite PVs has increased from ca. 3% to a current level in excess of 20%. This efficiency is now comparable to that of crystalline Si and semiconductor thin films (e.g., copper indium gallium selenide (CIGS), CdTe) that have been in development since the 1970’s. Perovskite solar technology utilizes a hybrid inorganic-organic halide perovskite (e.g., CH3NH3MI3 where M = Sn, Pb) in combination with n- and p-type charge collection layers. In a promising step toward aesthetically attractive solar panels, Zhang and coworkers describe the fabrication of perovskite photovoltaic devices that are color-tunable. In order to maximize the refractive index contrast among the layers in the device, nanoparticulate films of porous SiO2 (50% porosity) and dense TiO2 (4% porosity) were deposited by simple spin-coating. The combination of the photonic properties of the oxide nanoparticle films and absorptive properties of the overlying perovskite material was used to fine-tune the observed color range from orange to blue. Interestingly, the strategy employed by these researchers may be considered as a biomimetic approach, since beetles and butterflies also employ reflective and absorptive layers that yield a characteristic and often tunable color. Many gemstones such as opals also utilize the photonic crystal effect to give rise to iridescent colors. The use of a photonic phenomenon for color generation in this multilayered PV device is preferred rather than using dyes or pigments, since the latter would likely fade over time. The best power conversion efficiency observed in this work was 8.8% for blue-colored cells. While this is low relative to traditional perovskite-based PV devices, this may be compared to 9.5% for a reference cell employing mesoporous SiO2. Hence, the operating efficiency of the device is not significantly deteriorated by the reflective processes occurring in the photonic component of the device, which is responsible for the observable colors. Further fine-tuning of the perovskite layers, interfaces, and nanoparticle sizes and porosities will likely improve the overall efficiency, while expanding its color palette. It would be interesting to extend this approach to other emerging technologies and thin film semiconductors to introduce other options for colorful solar panels. As decorative options become more plentiful and efficiencies continue to rise, consumers will more likely adopt this technology to power their homes and begin to wean themselves from nonrenewable fossil fuels. Electric and hybrid vehicles employing solar panels that match the color of the exterior paint would also be much more attactive to consumers relative to traditional solar panels already used by some vehicles (e.g., Fisker Karma). Reference: Zhang W, Anaya M, Lozano G, Calvo ME, Johnston MB, Míguez H, Snaith HJ. Highly Efficient Perovskite Solar Cells with Tunable Structural Color. Nano Letters. 2015; 15 (3): 1698-1702 doi: 10.1021/nl504349z (http://pubs.acs.org/doi/abs/10.1021/nl504349z) Image reprinted with permission from American Chemical Society.

Handwritten Patterning of Single-Walled Carbon Nanotubes

National Nanomanufacturing Network - March 19, 2015 - 4:29am
Although there are many potential applications for carbon nanotubes (CNTs), their wide scale consumer applications to date have been limited to serving as polymer additives to yield higher-strength composites. Even though bulk nanotubes exhibit tensile strengths much less than individual nanotubes (especially single-walled varieties), bulk CNT additives have been shown to enhance the strength:weight ratio of a variety of sporting equipment such as bicycles, skies, baseball bats, hunting arrows, and surfboards. Beyond their high-strength properties, the extraordinary electrical conductivity of CNTs makes these nanostructures ideal for microelectronics circuitry applications. Using advanced techniques such as near-field electrospinning (NFES), it is now possible to generate conductive nanotube fibers that span up to a few hundred meters. However, current fiber processing techniques are difficult to scale up, and often experience difficulties with nanotube alignment during fiber spinning. This latter limitation is an important consideration for microelectronics applications, since unaligned nanotubes would deleteriously affect the conductivity of the deposited fibers. The recent report by Huang et al. describes an improved fiber-drawing technique that consists of simple handwriting of conductive fibers using a common pen tip. Patterns may easily be placed onto both planar and non-planar substrates using this strategy. The fiber drawing speed is reported to be ca. 10 cm/s, which represents a large improvement relative to other techniques that are much too slow for commercial scale up, with patterning speeds of < 1 mm/s (most often in the mm/s range). Patterning consists of using poly(ethylene oxide), PEO, in the presence of surfactants and carbon nanotubes, which forms a polymeric ‘ink’. The choice of PEO was due to its desirable viscoelastic properties, which allowed for the continuous pulling of fibers from the solution without breakage. In contrast, fibers drawn from solutions of poly(methyl methacrylate), PMMA, commonly used in other patterning techniques, have much larger diameters and inconsistent conductivities due to less effective alignment of nanotubes comprising the fiber. Whereas PEO in the absence of CNTs dried to form nanofibers with diameters of ca. 60 nm, the diameter range of PEO-CNT composite fibers was ca. 300 nm – 3 mm. One is able to vary the diameter of the composite PEO-CNT fibers, based on the solution concentration and volume used in the pen tip. Fiber lengths in excess of 50 cm were achieved using this technique, and featured a high degree of nanotube alignment – especially for low-diameter fibers. Consequently, the conductivity of the fibers were significantly higher than isotropic CNT thin films. In contrast to other techniques that require the use of micro/nanomanipulators to appropriately position fibers into electronic circuitry, this direct-writing procedure is able to place the conductive fibers directly into desired positions with submicron control. The fibers may also be transferred to other substrates after drying without changing their morphologies or electrical conductivities. With a surge in flexible and wearable electronic devices on the horizon, it is essential that techniques exist for the fabrication of flexible conductive wires. This work represents an attractive strategy, and results in fibers that may be easily fabricated using a common pen tip and placed onto a variety of surfaces. Furthermore, the conductivity of the fibers is not altered by repeated bending tests, which should enable this technique to be used for the next generation of flexible touchscreens, wearable electronics, and the batteries or supercapacitors that will be needed to power these devices. Further testing is needed to assess the adsorption of the PEO-CNT fibers to textiles, LCDs, and other surfaces. However, this technique shows promise for the fast assembly and precise placement of conductive fibers into electronic circuits. Reference: Huang S, Zhao C, Pan W, Wu H. Direct Writing of Half-Meter Long CNT Based Fiber for Flexible Electronics. Nano Letters. 2015; 15 (3): 1609-1614 doi: 10.1021/nl504150a (http://pubs.acs.org/doi/abs/10.1021/nl504150a) Image reprinted with permission from American Chemical Society.

NNI Publishes Report on Carbon Nanotube (CNT) Commercialization

National Nanomanufacturing Network - March 13, 2015 - 4:35am
The National Nanotechnology Initiative today published the proceedings of a technical interchange meeting on “Realizing the Promise of Carbon Nanotubes: Challenges, Opportunities, and the Pathway to Commercialization" (http://www.nano.gov/node/1339) held at the National Aeronautics and Space Administration (NASA) Headquarters on September 15, 2014. This meeting brought together some of the Nation’s leading experts in carbon nanotube materials to identify, discuss, and report on technical barriers to the production of carbon nanotube (CNT)-based bulk and composite materials with properties that more closely match those of individual CNTs and to explore ways to overcome these barriers. A number of common themes and potential future research and development priorities emerged: Increased efforts devoted to manufacturing, quality control, and scale-up.Improvements in the mechanical and electrical properties of CNT-based bulk materials to approach the properties of individual CNTs.More effective use of simulation and modeling to provide insight into the fundamentals of the CNT growth process.Improved understanding of the properties of bulk CNT-containing materials at longer length scales.Standard materials and protocols to guide the testing of CNT-based products for commercial applications.Life cycle assessments for gauging commercial readiness.Use of public-private partnerships or other collaboration vehicles to leverage resources and expertise to solve these technical challenges and accelerate commercialization. The outcomes of this meeting, as detailed in this report, will help inform the future directions of theNNI Nanotechnology Signature Initiative “Sustainable Nanomanufacturing: Creating the Industries of the Future,” (http://nano.gov/NSINanomanufacturing) which was launched in 2010 to accelerate the development of industrial-scale methods for manufacturing functional nanoscale systems. You can download full document from the InterNano Library (http://eprints.internano.org/2228/) .

U.S. National Nanotechnology Initiative 2016 funding brings total to $22 billion

National Nanomanufacturing Network - March 12, 2015 - 5:53am
The President’s Budget for Fiscal Year 2016 provides $1.5 billion for the National Nanotechnology Initiative (NNI), a continued Federal investment in support of the President’s priorities and innovation strategy. Cumulatively totaling more than $22 billion since the inception of the NNI in 2001, this funding reflects nanotechnology’s potential to significantly improve our fundamental understanding and control of matter at the nanoscale and to translate that knowledge into solutions for critical national needs. Nearly half of the requested budget is dedicated to applications-focused R D and support for the Nanotechnology Signature Initiatives (NSIs), reflecting an increased emphasis within the NNI on accelerating the transition of nanotechnology-based discoveries from lab to market. The NSIs are multiagency initiatives designed to accelerate innovation in areas of national priority through enhanced interagency coordination and collaboration. Furthermore, the NNI has continued to grow its hallmark environmental, health, and safety (EHS) activities, which now account for more than 10% of the NNI’s total budget (7% in dedicated EHS investments, as shown in the figure at left, plus approximately 3% in additional EHS-related investments within the NSIs). “Right now, the NNI is focused on innovations that support national priorities, while maintaining a strong foundation of fundamental research in nanoscience,” says Dr. Michael Meador, Director of the National Nanotechnology Coordination Office. “Our goal is to create an environment to foster technology transfer and new applications today, while supporting the basic research that will provide a continuing pipeline of new discoveries to enable future revolutionary applications tomorrow.” The President’s 2016 Budget supports nanoscale science, engineering, and technology R D at 11 agencies; another 9 agencies have nanotechnology-related mission interests or regulatory responsibilities. The NNI Supplement to the President’s 2016 Budget documents activities of these agencies in addressing the goals and objectives of the NNI. You can download full document from the InterNano Library (http://eprints.internano.org/2227/).Source: nano.gov (http://nano.gov/node/1326)