Demonstration of the flexibility of cellulose–silica composite aerogel. Credit: J. Cai et al.; Angewandte Chemie.

This sounds like the type of breakthrough aerogel fans have yearning for.

A newly published paper in Angewandte Chemie reports on an Asian group’s success at using cellulose fibers as a scaffold/template for a resultant silica aerogel that delivers a product that has great mechanical strength and flexibility, while retaining a large surface area and semitransparency.

Aerogel has been something of a tease for many years. It has incredible insulating abilities, but the one enormous problem for silica aerogel is that it is frustratingly brittle and difficult to work into practical applications. Some developers have found limited success via hybridization techniques with support materials such as polyurethane, polystyrene or even nanofibrillar bacterial cellulose and microfibrillated cellulose gel.

However, with support from the Japan Society for the Promotion of Science’s Foreign Researcher Fund of Japan and the National Basic Research Program of China, researchers at Wuhan University, China, and University of Tokyo, took a different cellulose-based route. They already knew that they could exploit “cellulose II” crystallinity  (dissolution and then regeneration/reassembly of fibrils) to form aerogels with good mechanical strength, light transmittance and high porosity — characteristics that they suspected would make it an effective substrate for silica aerogel.

In brief, the group, led by Lina Zhang, impregnated a sample of nanoporous cellulose gel (with its interconnected nanofibrillar network) with a silica precursor, tetraethyl orthosilicate. According to the paper, “The resulting composite gels were dried with supercritical CO₂ to give cellulose–silica aerogels with low density, moderate light transmittance, a large surface area, high mechanical integrity and excellent heat insulation.”

They then went one step farther and used calcination to remove the cellulose matrix, leaving a silica-only aerogel. The key point here is that this silica aerogel’s structure is much different than pure silica aerogel. In the latter, primary silica nanoparticles form and then randomly coagulate resulting in an isotropic 3D network. “In contrast,” again quoting from the paper, the authors say, “the formation of silica nanoparticles in the cellulose gel seems to cause their deposition onto the cellulose fibrils. As a result, removal of cellulose by calcination results in the nanofibrillar silica network.”

The group compared a variety of aerogels, including silica-only and cellulose-only aerogels; cellulose-silica composites, with varying levels of silica; and cellulose-templated silica aerogel.

What they found at the macroscopic level is that the composite aerogels didn’t inherit the fragility of the silica, but instead seem to inherit the flexibility and strength of the cellulose network (see knotted sample of one of the composites, above).

While the tensile modulus and strength of the cellulose–silica aerogel were less than pure cellulose aerogel, “the compression modulus of the composite (7.9MPa) is more than two orders of magnitude higher than that of silica aerogel, and about 50 times higher than that of the aerogel prepared from bacterial cellulose.”

Because of the cellulose content, the composite aerogels break down when used above 300°C. However, below that temperature, the cellulose-silica aerogel retained strong heat insulating properties. Thermal conductivity of the prepared samples ranged from 0.025 W m^-1 K^-1 to 0.045 W m^-1 K^-1.

These numbers compare favorably with polystyrene foam (0.030 W m^-1 K^-1), however, the researchers note that the ability of the cellulose–silica aerogels to perform up to 300°C give it a leg up on insulation materials made of polymer that soften and breakdown at similar temperatures.

“Thus,” according to the authors,”the cellulose–silica composite is potentially useful as heat insulating material with high mechanical stability, together with processability to form sheets, fibers, or beads. … [They] retained the mechanical strength and flexibility, large surface area, semitransparency, and low thermal conductivity of the cellulose aerogels. The ease of preparation and wide tuneability of composition/properties with this method are expected to form the basis for the development of various advanced nano-porous materials.”

The paper, ”Cellulose-silica nanocomposite aerogels by in situ formation of silica in cellulose gel,” (doi:10.1002/ange.201105730) is written by Jie Cai, Shilin Liu, Jiao Feng, Satoshi Kimura, Masahisa Wada, Shigenori Kuga, and Lina Zhang.

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Framework for new report by a committee of the National Research Council for the National Academies. Credit: NRC.

Nano environmental health and safety is clearly an important topic and one that is frequently referenced at materials conferences I have attended. But despite all the balloon juice, it seems to me that work over the last few years on research, documentation and development of databases on the safety and health of various nanomaterials hasn’t gone very far.

Good people at NIST, NIH and other institutions have been working for at least five year on trying to get some momentum going, and I do get that the nano EHS work is complicated (and that there yet seems to be even a common language among various researchers and between the research and industry communities) and expensive, but unfortunately, it feels like there is little substantial progress being made.

I think the National Academies agrees:

The committee that wrote the [a new report from the National Research Council] found that over the last seven years there has been considerable effort internationally to identify research needs for the development and safe use of nanotechnology, including those of the National Nanotechnology Initiative, which coordinates US federal investments in nanoscale research and development. However, there has not been sufficient linkage between research and research findings and the creation of strategies to prevent and manage any risks. For instance, little progress has been made on the effects of ingested nanomaterials on human health and other potential health and environmental effects of complex nanomaterials that are expected to enter the market over the next decade. Therefore, there is the need for a research strategy that is independent of any one stakeholder group, has human and environmental health as its primary focus, builds on past efforts, and is flexible in anticipating and adjusting to emerging challenges, the committee said.

The committee recommends four research categories “which should be addressed within five years:”

• Identify and quantify the nanomaterials being released and the populations and environments being exposed;
• Understand processes that affect both potential hazards and exposure;
• Examine nanomaterial interactions in complex systems ranging from subcellular to ecosystems; and
• Support an adaptive research and knowledge infrastructure for accelerating progress and providing rapid feedback to advance research.

Will Washington fund such efforts? It’s hard to know given the political environment, and the NRC warns, “[A]ny reduction in the current funding level of approximately $120 million per year over the next five years for health and environmental risk research by federal agencies would be a setback to nanomaterials risk research.”

NRC also says other public, private and global resources will be needed in the areas of “informatics, nanomaterial characterization, benchmarking nanomaterials, characterization of sources and development of networks for supporting collaborative research.”

I haven’t had a chance to read the 200+ page report, but the summary seems to contain a fairly thorough strategy, with one exception: It’s not very helpful in suggesting how to implement the strategy, which always has seemed to me to be the weakness in these discussions. Someone logically has to be given the power and resources to wrangle all of the stakeholders.

What about the NNI? Can it spearhead the effort? The committee astutely puts the kybosh on that notion, at least with the current configuration of NNI agencies:

The committee said that the current structure of the NNI — which has only coordinating functions across federal agencies and no top-down budgetary or management authority to direct nanotechnology-related environmental, health, and safety research — hinders its accountability for effective implementation. In addition, there is concern that dual and potentially conflicting roles of the NNI, such as developing and promoting nanotechnology while identifying and mitigating risks that arise from its use, impede application and evaluation of health and environmental risk research. To carry out the research strategy effectively, a clear separation of management and budgetary authority and accountability between promoting nanotechnology and assessing potential environmental and safety risks is essential.

Its not clear to me if the NRC/NAS has an alternative to the NNI leadership in mind, or just a restructuring of NNI, but the committee says whatever group is in charge will require “sufficient management and budgetary authority to direct development and implementation of a federal EHS strategy across NNI agencies and to ensure integration of federally supported EHS research with research undertaken by the private sector, the academic community and international organizations.” In other words, the dual NNI responsibilities of simultaneously promoting nanomaterials and assessing their EHS effects generates lots of conflicts and therefore accountability for the two should be clearly separated.

Addendum from Eileen: The Danish have taken a first stab at addressing exactly this issue, according to a press release published today. The Danish Environmental Protection Agency, the Technical University of Denmark and the National Research Centre for the Working Environment collaborated on developing a database concept for cataloging and evaluating the risks associated with nanomaterials. The Executive Summary of the report (pdf) explains:

Through this project, DTU Environment and the National Research Centre for the Working Environment have initiated the development of a screening tool, NanoRiskCat (NRC), that is able to identify, categorize and rank expo- sures and effects of nanomaterials used in consumer products based on data available in the peer-reviewed scientific literature and other regulatory relevant sources of information and data. The primary focus was on nanomaterials relevant for professional end-users and consumers as, as well as nanomaterials released into the environment.

They used nanosized TiO₂ (used in sunscreens) and C₆₀ (used in lubricants) as demonstration materials for the database.

To make it easy to evaluate risks quickly, a color coded five-dot system was developed, where the first three dots “refer to potential exposure of professional end-users, consumers and the environment,” and the last two dots “refer to the hazard potential for humans and the environment.”

The color code scheme is the universally recognized red, yellow and green, corresponding to high, medium and low risks. In cases where the risk is unknown, the dot is grey.

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Some of the German delegation of participants in the first Global Young Investigators Forum at ICACC. Thomas Fisher (third from left) was the principle organizer of the forum.

The 36th convening of the International Conference and Exposition on Advanced Ceramics and Composites is in its second day in Daytona Beach, Fla. This year’s meeting attracted over 1,000 engineers and scientists from 41 countries, who will be presenting about 850 papers. According to the organizers, this year, for the first time, the number of foreign attendees has surpassed the number of US attendees.

Two factors are contributing to the strong international participation: the first European Union–USA Ceramics Summit and the first Global Young Investigators Forum. The EU-USA summit is taking place on Monday and Tuesday and attracted about 25 talks with participants from Germany, Italy, Sweden, Czech Republic, Finland, Belgium, Poland and Spain.

The Global Young Investigators Forum starts tomorrow and runs through the end of the week. The GYIF is a new innovation this year, and all indications are that it’s an idea that is long overdue. Thomas Fisher, PhD candidate at the University of Cologne, Germany, organized the Forum, which will have 45 presentations from PhD candidates and post-docs from more than 14 countries. I’ll have more to tell about the Forum later.

I’m told the weather in Daytona Beach in January can be hit or miss, and since Sunday, it’s been all “hit,” with temperatures in the upper 70s and sunshine.

Here is a catalog of some of the things I’ve been seeing.

George Wicks, ACerS president, and Sanjay Mathur, program chair.

ICACC'12 kicked off with a lively reception on Sunday.

Colleagues and friends met at the reception. Pictured from the left, Lise Schioler, George Quinn and Eileen De Guire.

Jay Singh presented the Society with a gift on behalf of the Indian Ceramic Society. Pictured with Jay are Charlie Spahr (ACerS executive director), George Wicks and Megan Bricker (ACerS director of membership).

Monday's plenary session drew a rapt audience.

David Marshall delivered the first plenary talk and was awarded the James I. Mueller Award.

The beach was no distraction for these attendees.

Andrew Portune of Nottingham, Md., is enjoying the meeting.

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The Florida-based Boca Bearing Co., a maker of ceramic ball bearings, announced that it will celebrate its 25th year in business by giving away over $20,000 in cash and prizes in an international innovation contest. Besides being a way to highlight its anniversary and show its appreciation to customers, the company says it hopes the contest will support those eager to push the limits of new technologies that will drive the future economy.

Boca Bearing officials say entrants must have a project that involves ball bearings, roller bearings or linear bearings. Winners will be chosen based on a video submission of that should emphasize how the project is innovative, progressive or overall “cool.”

The company says that one finalist will be chosen by the voting public each month in 2012, with that monthly winner winning an iPad2. Finally, a grand prize winner will be chosen by the company and he or she will receive a grant check for $10,000.

The two runners up will also be chosen from among the monthly winners and each win their own 3D printer from MakerBot Industries (~$2,500 value each).

For inspiration of what might be submitted as an entry, the company suggests that any mechanical device that requires either linear or rotary motion generally also requires a bearing to make that motion more efficient.  Some suggestions: unmanned autonomous vehicles, robots, kinetic art sculptures, engine hacks, performance racing applications, sustainable energy projects and much more.

A concrete lathe, an example of one of the submissions to contest.

Boca Bearings has set up a special web page for the contest that includes more detailed information about the submission process, rules, FAQs and the judging process. The public can also use the page to vote for monthly winners.

The company also reports that it is going to continue its support for the 10,000-year-clock project. This is a specially engineered clock designed to run for ten millennia with little maintenance, powered by solar energy and mechanical energy from the people who visit it. The primary materials used in the clock are marine grade 316 stainless steel, titanium and dry running ceramic ball bearings supplied by Boca Bearings.

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Beautiful weather in Orlando, Fla. beckoned these attendees at the Electronic Materials and Applications meeting.

The 2012 Electronic Materials and Applications meeting opened yesterday in Orlando, Fla. This is the third consecutive year for the event organized by ACerS’ Electronics Division and Basic Science Division, and this year’s gathering attracted just under 200 participants.

The program focuses on electronic ceramics for energy generation, conversion and storage applications. There are eight symposia covering advanced dielectrics, piezoelectrics, materials for batteries, thermoelectrics, metamaterials and microwave materials, as well as a symposium dedicated to sustainability and green materials processing.

Yesterday’s plenary speaker was Tony Gozdz, principle scientist at A123 Systems, pinch-hitting for Bart Riley one of the cofounders of A123, who was unable to come at the last minute. Gozdz, a polymer chemist by training, really knows batteries and set the tone for the conference by outlining the materials science and engineering successes, ambitions and challenges that are yet to be overcome.

The talk, “Advances in Lithium-ion Technology for Automotive and Grid Application,” started with a brief history of battery technology and quickly focused in on the development of lithium-containing batteries beginning in the 1960s. Observing, “The chemistry of batteries is the chemistry of interfaces, basically,” Gozdz went on to describe how solutions to surface and interface problems drove the evolution of lithium batteries, and continues to do so. He outlined A123’s work developing nanophosphate cathode materials, and offered some thoughts on nascent energy storage ideas and on the energy paradigm shift underway in this country. I’ll have more on the three plenary talks in a later post.

Meanwhile, enjoy this photoblog from Orlando!

Amit Goyal, chair of the Electronic Division, welcomes attendees to EMA 2012

Tony Gozdz of A123 Systems delivered the opening plenary talk on lithium batteries for automotive and grid applications.

Students polish their talks during the mid-morning coffee break.

A special symposium gave students the opportunity to present their work. Here, Manuel Rivas, a senior at U. Texas-Pan American, presents his work on doped barium titanate.

Christopher Turner, PhD candidate at U. Florida, fields questions during the poster session and reception.

Alp Sehirlioglu and Geoff Brennecka at the reception.

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