110Rev.Adv.Mater.Sci. 5 (2003) 110-116 Ken P. Chong NANO SCIENCE AND ENGINEERING IN MECHANICS AND MATERIALS Ken P. Chong Directorate for Engineering, National Science Foundation, Arlington, VA 22230, USA Abstract. The transcendent technologies include nanotechnology, microelectronics, information technology and biotechnology as well as the enabling and supporting mechanical and civil infrastructure systems and materials. These technologies are the primary drivers of the twenty first century and the new economy. Mechanics and materials are essential elements in all of the transcendent technologies. Research opportunities, education and challenges in mechanics and materials, including nanomechanics, carbon nano-tubes, bio-inspired materials, coatings, fire-resistant materials as well as improved engineering and design of materials are presented and discussed in this paper. 1. INTRODUCTION 10-6 m ELASTICITY; PLASTICITY; DISLO- CATION... Nanotechnology is the creation of new materials, 10-3 m MECHANICS OF MATERIALS devices and systems at the molecular level - phe- 10-0 m STRUCTURAL ANALYSIS nomena associated with atomic and molecular in- MULTI-SCALE ANALYSES & SIMULATIONS teractions strongly influence macroscopic material properties [according to I. Aksay, Princeton]; with The National Science Foundation has supported significantly improved mechanical, optical, chemical, basic research in engineering and the sciences in electrical... properties. Nobelist Richard Feynman the United States for a half century and it is ex- back in 1959 had the foresight to indicate there is pected to continue this mandate through the next plenty of room at the bottom. National Science century. As a consequence, the United States is Foundation [NSF] Director Rita Colwell in 2002 de- likely to continue to dominate vital markets, because clared nanoscale technology will have an impact diligent funding of basic research does confer a pref- equal to the Industrial Revolution. erential economic advantage (Wong, 1996). In the education area in order to do competitive Concurrently over this past half century, technolo- research in the nanotechnology areas, engineers gies have been the major drivers of the U. S. should also be trained in quantum mechanics, economy, and as well, NSF has been a major sup- molecular dynamics, etc. The following lists some porter of these technological developments. Accord- of the key topics across different scales. The au- ing to the former NSF Director for Engineering, Eu- thor has been advocating a summer institute to train gene Wong, there are three transcendental tech- faculty and graduate students to be knowledgeable nologies: in scales at and less than the micrometer (see: · Microelectronics Moores Law: doubling the http://tam.northwestrn.edu/summerinstitute/ capabilities every two years for the last 30 years; Home.htm) unlimited scalability; nanotechnology is essen- 10-12 m QUANTUM MECHANICS [TB, DFT, tial to continue the miniaturization process and HF ]* efficiency. 10-9 m MOLECULAR DYN. [LJ ]; *TB = TIGHT BINDING METHOD; DFT = DENSITY FTNAL NANOMECHANICS; MOLECULAR BIOLOGY; THEORY; HF = HATREE-FOCK APPROX.; LJ = LENNARD BIOPHYSICS JONES POTENTIAL Corresponding author: Ken P. Chong, e-mail: [email protected] © 2003 Advanced Study Center Co. Ltd. Nano science and engineering in mechanics and materials 111 · Information Technology [IT] NSF and DARPA as single-electron transistor; logic gate started the Internet revolution more than three as RAM on/off do not affect memory storage - decades ago; the confluence of computing and no booting needed. communications. Sources: · Biotechnology unlocking the molecular secrets CARBON NANOTUBES THE FIRST 10 YEARS, NATURE, of life with advanced computational tools as well 2001. as advances in biological engineering, biology, MECHANICAL ENGINEERING, ASME, NOV. 2000 chemistry, physics, and engineering including TECHNOLOGY REVIEW, MIT, MAR. 2002 mechanics and materials. Considerable NSF resources and funding will be Efficient mechanical and civil infrastructure sys- available to support basic research related to nano tems as well as high performance materials are science and engineering technologies. These op- essential for these technologies. By promoting re- portunities will be available for the individual search and development at critical points where investigator, teams, small groups and larger inter- these technological areas intersect, NSF can fos- disciplinary groups of investigators as well as cen- ter major developments in engineering. The solid ters. Nevertheless, most of the funding at NSF will mechanics and materials engineering (M&M) com- continue to support unsolicited proposals from indi- munities will be well served if some specific link- vidual investigator on innovative blue sky ideas in ages or alignments are made toward these tech- all areas including nano science and engineering nologies. technologies. Some thoughtful examples for the M&M and other engineering communities are: 2. NANOTECHNOLOGY · Bio-mechanics/materials Nanomechanics Workshop · Simulations/modeling Initiated by the author, with the organization and help · Thin-film mechanics/materials of researchers from Brown [K. S. Kim, et al.], · Micro-electro-mechanical systems (MEMS) Stanford, Princeton and other universities, a NSF · Wave Propagation/NDT Workshop on Nano- and Micro-Mechanics of Sol- · Smart materials/structures ids for Emerging Science and Technology was held · Nano-mechanics/materials at Stanford in October 1999. The following is ex- · Nano-electro-mechanical systems(NEMS) tracted from the Workshop Executive Summary. · Designer materials Recent developments in science have advanced · Fire Retardant Materials and Structures. capabilities to fabricate and control material sys- MEMs can be used as platforms for NEMS. tems on the scale of nanometers, bringing problems Another product of the nanotechnology is carbon of material behavior on the nanometer scale into the nano-tubes [CNT] which are self-assembled in depo- domain of engineering. Immediate applications of sition from C-rich vapors, consisted of honeycomb nanostructures and nano-devices include quantum lattices of carbon rolled into cylinders; nm in diam- electronic devices, bio-surgical instruments, micro- eter, micron in length. CNT have amazing proper- electrical sensors, functionally graded materials, and ties: many others with great promise for commercializa- 1/6 the weight of steel; 5 times its Youngs modu- tion. The branch of mechanics research in this lus; 100 times its tensile strength; 6 orders of emerging field can be termed nano- and micro-me- magnitude higher in electrical conductivity than chanics of materials, highly cross-disciplinary in copper; CNT strains up to 15% without breaking character. A subset of these, which is both scien- 10 times smaller than the smallest silicon tips tifically rich and technologically significant, has in Scanning Tunnel Microscope - STM [CNT is mechanics of solids as a distinct and unifying theme. the worlds smallest manipulator] The presentations at the workshop and the open CNT may have more impact than transistors discussion precipitated by them revealed the emer- ideal material for flat-screen TV [~2003] gence of a range of interesting lines of investigation similar diameter as DNA built around mechanics concepts that have poten- bridge different scales in mesoscale - useful as tial relevance to microelectronics, information tech- bldg. blocks ~ e.g. nanocomposites; gases stor- nology, bio-technology and other branches of age nanotechnology. It was also revealed, however, that metallic or semiconducting the study of complex behavior of materials on the nanometer scale is in its infancy. More basic re- 112 Ken P. Chong Fig. 1. Instruments and techniques for experimental micro and nano mechanics [courtesy of K. S. Kim of Brown University] where HRTEM High Resolution Transmission Electron Microscopy, SRES Surface Roughness Evolution Spectroscopy, CFTM Computational Fourier Transform Moire, FGLM Fine Grating Laser Moiré, AFM Atomic Force Microscopy, LSI Laser Speckle Interferometry, SEM Scanning Electron Microscopy, DIC Digital Image Correlation, LDLM Large Deformation Laser Moire. search that is well coordinated and that capitalizes To improve the speed and performance of the on progress being made in other disciplines is atomic force microscope, more optimal control of needed if this potential for impact is to be realized. the cantilever and more robust software to acquire Recognizing that this area of nanotechnology is and process the data as well as other improvements in its infancy, substantial basic research is needed are needed. A portable AFM has also been devel- to establish an engineering science base. Such a oped by IBM recently. commitment to nano- and micro-mechanics will lead The potential of various concepts in to a strong foundation of understanding and nanotechnology will be enhanced, in particular, by confidence underlying this technology based on exploring the nano- and micro-mechanics of coupled capabilities in modeling and experiment embody- phenomena and of multi-scale phenomena. Ex- ing a high degree of rigor. The instruments and tech- amples of coupled phenomena discussed in this niques available for experimental micro- and nano- workshop include modification of quantum states of mechanics are depicted in Fig. 1, courtesy of K. S. materials caused by mechanical strains, ferroelec- Kim of Brown University. tric transformations induced by electric