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03.06.2013
Feature> Matters of Substance
Bill Millard plumbs the field of materials science in search of the next transformative technology.
Jenny Sabinns myThread Pavilion for Nikees FlyKnit Collective explores biodynamic models and data sets to illiuminate new ways of thinking about material structures.
Courtesy Jenny Sabin

If, as Louis Kahn said, a brick wants to be part of an arch, what does a biopolymer molecule, a block of aerogel, or a slab of metallic foam want to be? The empirical basis for inferring bricks’ intentions is well established, comprising building traditions that have evolved over millennia. For newer materials, the chance of moving from laboratories to construction sites can be a crapshoot. The successful ones not only capture markets but transform behavior.

The most promising approaches, materials specialists agree, emphasize integration rather than isolation. “We don’t just create materials or products; we create information systems,” says architect/author Blaine Brownell, who co-directs the MS in Sustainable Design program at the University of Minnesota and whose most recent book, Material Strategies: Innovative Applications in Architecture (Princeton Architectural Press, 2012), links innovations in minerals, concrete, wood, metal, glass, and plastics to prominent case studies. Using the term hypermaterial to denote the convergence of materials and information processing, Brownell looks to the management of light, energy, and data as the leading edge of materials research.

 
Courtesy Jenny Sabin
 

Jason O. Vollen, associate director of the Center for Architecture Science and Ecology (CASE), a joint project of Rensselaer Polytechnic Institute and SOM, heralds “a fundamental paradigm shift from moving energy mechanically, which is how we do it now, to moving energy materially.” Instead of multiple layers of a structure performing different functions, Vollen says, as in Mike Davies’ concept of the polyvalent wall, “We think one layer should do multiple things; we think a potential solution is the multivalent material. That’s not so far off; it’s speculative fiction rather than science fiction.” Citing the “holy grail” of Lawrence Berkeley National Laboratory’s Stephen Selkowitz—a material optimizing both daylight and insulation—Vollen says “what exists now won’t do that, but what exists around the corner might.” Nanotechnology, where categories blend and “metals can become more like glasses, glasses become more like ceramics,” he continues, is yielding unprecedented control over properties such as heat flow and daylight transmittance. With high-performance ceramics in particular offering properties that answer climate-change-driven imperatives, he is convinced, “the industry is poised for a revolution.”

Materials research is often a matter of systematic biomimicry, invoking a parallel understanding of natural processes occurring over time on multiple scales, from the nanoscale to the visible to the ecosystemic. “It’s not about translating shape, or a static image of a biological behavior,” says Jenny E. Sabin, assistant professor of architecture at Cornell and a founding member of Cecil Balmond’s Nonlinear Systems Organization. As the architectural member of the National Science Foundation-sponsored ESkin interdisciplinary team, which also includes a materials scientist, a cell biologist, and a systems engineer, Sabin investigates homologies in materials, geometries, and forms. She describes her challenge as “thinking about how those properties could work across scales” and replicating them in “highly engineered, sustainable materials that have very sophisticated responses to environmental cues.”

Courtesy Jenny Sabin
 

Generative models based on cellular activity inform her “Branching Morphogenesis” installation at Linz, Austria’s 2009 Ars Electronica (comprising 75,000 cable zip ties in tension, organized according to microscale cellular forces) and her all-knitted myThread Pavilion for Nike’s Flyknit Collective, produced with New Jersey-based fabricator Shima Seiki USA. “It’s not just that we can produce complex organic form,” she continues, but that designers can “directly interact with manufacturing technologies...Working with soft textile-based materials at a large scale is only possible through really cutting-edge fabrication technologies.” Strategies that arise from these investigations include “embedding a more nonlinear lifespan” into a material, so that products pass usefully through multiple life cycles; porosity, allowing lightness and transmissibility as well as strength; geometries that repel or absorb water, a high priority in materials that must endure sea-level rise; and self-organizing properties on nano-to-macro scales.

The technological transition suggested by business consultant David Morris, vice president of the Institute for Local Self-Reliance—replacing the hydrocarbon-based economy, with all its externalities, costly extractive processes, and resource-availability constraints, with an older, cleaner system, “the once and future carbohydrate economy”—calls for more use of lifelike materials, Brownell suggests: those derived from agriculture and those deriving knowledge from living systems. A brick may want to be thick, but contemporary materials want to be smart.

Resource maximizers, beginning with light

Andrew H. Dent, PhD, vice president of library and materials research at Material ConneXion, sees two broad questions driving research in the field: what does Earth have in abundance, and what are we running out of? To the extent that materials and processes based on ample, readily available resources (from sunlight to silicon) replace those with sources in short supply (petroleum, gold, copper, clean air, and water), materials research represents a critical adaptation to emergent conditions.

Much of this work is economic optimization rather than new discovery, Dent adds. Methods of developing biopolymers from a wide range of plants harvested in different regions and conditions (corn, castor, switch grass, sugar cane, potatoes, and others) are already known. “The issue is how to beat out oil,” he says, which “even at a high price is still significantly cheaper.” Tradeoffs of this sort are inevitable. A material may be lightweight enough that its production and transport save energy and yield an admirable overall ecological footprint, but its components pose toxicity concerns, as with ethylene tetrafluoroethylene (ETFE, the transparent insulating “pillow” material seen in the 2008 Olympic Water Cube and other buildings worldwide). Biopolymers for construction, consumer products, or fuel, likewise involve edible crops and thus compete with food production. “Back in 2006 and early ’07,” Brownell recalls, “when there was so much excitement about biofuels and ethanol...states like Iowa were promising all kinds of fuel-making capacity without taking a hard look at how a lot of this corn that we make goes to developing countries in order to feed the world.” Vollen frames this starkly as “a political and regulatory issue: ‘if we replace oil with corn, what do we eat?’”

Sensitile’s light-piping panels harvest and manipulate light through optical channels embedded in concrete and resin substrates.
Courtesy Sensitile
 

In this regard, viewing solar energy as the ultimate free resource, Brownell is particularly enthusiastic about products that harvest and manipulate light, such as Sensitile’s light-piping panels, embedding optical channels in concrete and resin substrates, or a recent breakthrough at Duke University’s Pratt School of Engineering, scattering silver nanocubes on a gold film to “help the substrate absorb virtually all the light...so incredibly efficiently that nothing leaves the surface” and improving the efficiency of sensors. Another promising use of multiwall carbon nanotubes, he says, is field-induced polymer electroluminescent (FIPEL) technology, which generates a warm, nonflickering wavelength resembling sunlight­—“that spectrum that clearly influences human behavior and productivity in workplaces and learning places.” These flat lighting panels offer a distinct improvement over harsh compact fluorescents and heat-inefficient incandescents, with efficiency approaching that of LEDs.  Developed at Wake Forest University and licensed for commercial development to CeeLite Technologies, the panels can be integrated with flexible substrates and incorporated into windows or even textiles.

 
Courtesy Sensitile
 

Brownell also cites the engineer/designer Akira Wakita’s work with “conductive threads to make thermochromic and photochromic textiles that can act as computer monitors.” The importance of lighting in the developing world, he emphasizes, makes it a promising field for leapfrogging technologies that address “the good but tough 99 percent question” about new materials’ relevance to global populations, as well as a generally fertile field for disruptive technologies. “I’m still marveling at how LEDs have transformed the whole lighting field,” Brownell says. “It wasn’t that long ago [that] it was kind of hard to find an LED.”

Concrete, the most widely used construction material on Earth, is ripe for innovation. Its Portland cement component accounts for an estimated 5 percent of the global carbon footprint; by weight, concrete is environmentally friendlier than metals or polymers, Brownell says, but its sheer prevalence means that improving its performance has considerable ecological effects. Strategies include reducing cement volume with additives like blast furnace slag or rice husk ash (practiced by the Canadian firm EcoSmart). Then there is Calera’s carbonate mineralization by aqueous precipitation, which diverts preheated flue gas into seawater, combines energy production, cement manufacture, and carbon sequestration, and enhances CO absorption by using magnesium silicate, iron carbonate, or other alternative components. This process is done by TecEco in Tasmania, Novacem in London, and CarbonCure in Nova Scotia. (“Concrete strikes me as something like molé,” Brownell comments: “Every family has their own recipe.”)

Tensile strength is a concern with any concrete; among various high-performance crack-resistant concretes that use silica fume, superplasticizers, ground quartz, or mineral fibers, Victor Li’s work at the University of Michigan with fiber-reinforced, bendable concrete stretches the category’s definition altogether. Lafarge’s Ductal is another high-performance concrete that bridges the border between concretes and composites. A novel self-repair strategy developed at Newcastle University, BacillaFilla, programs a Bacillus subtilis strain to create calcium carbonate and a “microbial glue” when it is injected into cracks; it then cures to the same strength as the surrounding material (finally stopping, thanks to a genetic “kill switch” that keeps the bugs from surviving once they detect a surface; this feature relieves hypothetical sci-fi concerns about an uncontrollable Bill Joy-style gray goo).

The prospect that concrete could move from carbon-positive to carbon-negative strikes many commentators as an achievable goal—provided the newer variants gain market share, despite contractors’ comfort level with current recipes. “What we need,” suggests Dent, “are some high-profile architects to use some of [the new] material and show its advantages by being part of a high-profile, near-carbon-zero building.”

Victor Li at the University of Michigan has been experimenting with fiber-reinforced bendable concrete.
Courtesy University of Michigan
 

Material moneyball

Untested novelties face market resistance, particularly in areas where suboptimal technologies are entrenched, easily available, and (as Vollen points out) insurable. The factors that add up to successful technology transfer are far from systematic; for some materials, decades passed between their invention and commercialization. Dent hails Gorilla Glass, the ultra-strong, scratch-resistant surface that allows durability and interactivity in smartphones, as a transformative material that could also be useful in architecture. Yet when Corning developed the similar Chemcor glass in the early 1960s, it mothballed the product after about a decade, only to revive the idea on request from Apple in the mid-2000s. Serendipity and a suitable niche among related technologies appear essential for promising ideas to migrate from laboratory R&D to the Sweets catalog or the shelves of Home Depot.

One of nature’s recurrent strategies for economizing on material bulk—porous forms—characterizes several materials whose properties have drawn attention. Metallic foams, often aluminum or zinc, combine strength with lightness and thermal resistance; one such product, an aluminum foam marketed by the Canadian firm Cymat as SmartShield, was originally developed as a blast barrier on the undersides of military vehicles that encounter roadside bombs. “An individual at Cymat who had an architectural background recognized that, in addition to having the extreme technical properties, the material was aesthetically interesting,” reports Kelly Thomas, spokesperson for its distributor, Stone Source. Slightly altered in cell structure and slab thickness, rebranded as Alusion, the foam (80 percent air by volume) is now available to serve as walls, partitions, decorative fixtures, acoustic drop ceilings, or exterior cladding. Currently a specialty material, Alusion could conceivably gain increased prominence after the opening of the 9/11 Museum, where it will appear on the undersides of the twin fountains.

   
Lafarge’s Ductal is a high performance concrete reinforced by organic, reinforced metallic fibers that increases the material’s compression resistance, ductility, and longevity (left) Alusion, an aluminum foam that’s 80 percent air, was derived from Cymat, a material used as glass shielding on military vehicles (center, right).
Courtesy Lefarge; Courtesy Cymat
 

A class of even more ethereal materials, aerogels, has existed since the 1930s: they are exceptionally light (often called “frozen smoke”) and highly rated as thermal insulators. Brittleness limits their practical uses, though one aerogel, Kalwall+ Lumira, has found use as a translucent wall and skylight material. Recent work at NASA’s Glenn Research Center (GRC) in Cleveland, however, has generated polymer-based aerogels robust enough to resist crumbling and flexible enough for use in building insulation, clothing, autos, and elsewhere. About 500 times as strong as silica aerogels, with R values up to ten times those of polymer-foam insulation, NASA’s polyimide aerogel has attracted about 70 commercial inquiries since last August, reports GRC technology transfer specialist Amy B. Hiltabidel, with five possible U.S. manufacturers currently negotiating to license it.

It is too early to tell whether initial costs will drop enough for this material to catch on commercially, but Hiltabidel reports that on the GRC’s Technology Readiness Level scale, where a basic-research project rates a 1 and a 10 is already on the space shuttle, polyimide aerogel, “one of the first materials that has attracted such a varied interest” outside the aerospace/defense sector, is currently about a 6. “Because it’s more developed” than the average, she says, “it will have a faster time to market, and I would say well within five years, probably closer to two to three.”

Conceivably, either of these materials could become what every product wants to be: a market-maker that changes people’s expectations. Or both could end up in narrow niches. With any new technology, Vollen suggests, “what you probably want is not to bet on one horse; what you probably want to do, which is what nature has done, is bet on many horses. Within the larger ecosystem of material ecology and construction ecology, there will always be a place for new things to survive, and the longer each one of these things survives, the more fit it is, and the more it’s going to solve the problem, long-term.”

He analogizes commercial ecosystems to earthly ones: “In the ecological model, you think about what fills the void when something leaves: there’s always a gap... We think they’ll all find a place in the ecosystem, and we should encourage them. What’s really critical, I think now, is to encourage the process by which we use each building as an experiment, as a demonstration site, and see which one is going to be the model of fitness in the future.”

Bill Millard

Bill Millard is a New York City based writer and a frequent contributor to AN.