Jeff Brinker, a senior scientist at Sandia National Labs and a University of New Mexico professor, has discovered a new way of detecting mechanical, chemical, and thermal stress. Brinker uses intelligent nanostructures made from conjugated polymers that change from blue to red when changes in mechanical stress and temperature are introduced. The polymers change back to their original color when the stress and temperature changes are removed. The structures also change color in the presence of different solvents and chemicals. This colorful feat occurs at the nano level and involves linking monomers into polymers in an orderly fashion. "We have patents in progress on the general idea of self-assembly of nanocomposite materials," says Brinker. "We use surfactants both to direct the formation of the inorganic silica nanostructure and as monomers that become polymers in situ within the nanostructure to form the conjugated polymer," he explains. Conjugated polymers are typically similar to a bowl of entangled spaghetti, but Brinker found a way of organizing them. The materials are prepared by simple evaporation-driven processes like spin-coating, dip-coating, and ink-jet printing. Brinker notes the materials are easily integrated into devices, especially in thin-film form. By controlling interactions between the polymers, he effects the materials' electric and optical properties. The smart materials also serve mechanical functions such as protective coatings and permeation barriers. "Also, it is now recognized that to get better efficiency and function from conjugated polymers, it is necessary to organize them so as to control energy and electron transfer," says Brinker, adding that NASA, a sponsor of his work, is interested in thin films of the smart material for inflatable structures.
An in-depth survey of 700 current and future users of 3D printing holds few surprises, but results emphasize some major trends already in progress. Two standouts are the big growth in end-use parts and metal additive manufacturing (AM) most respondents expect.
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