Toward Greener Nanotechnology: Lessons from Functionalized Nanoparticle Synthesis Jim Hutchison hutch@uoregon.edu Department of Chemistry, University of Oregon Director, ONAMI Safer Nanomaterials and Nanomanufacturing Initiative (SNNI)
Merging green chemistry and nanoscience Green nanoscience - Applying the principles Examples from nanoparticle synthesis Research challenges New research to address challenges A proactive approach: Design and manufacture it right the first time! Gain/maintain public support Gain competitive advantage: Higher performance, cheaper and greener Real solutions, right now
Nanotechnology promises exciting breakthroughs for a thriving, sustainable future A clean, sustainable world for all future generations Abundant clean energy from the sun Drinkable water for everyone around the world Rapid, point-of-care medical diagnostics and treatment Novel therapeutics - A cure for cancer by 2020? http://www.nanospectra.com/
Growing concerns about nanotechnology stem from new, unknown properties and manufacturing challenges Will the products of nanotechnology. be harmful to human health? pose risks to the environment? Numerous studies and reports that suggest a need to address the hazards of these materials directly Lessons from GMOs - public acceptance as a barrier to commercialization Will the manufacture of these products generate new hazardous (toxic) wastestreams? Hazardous reagents Toxic solvents and high solvent usage Low yields of material (poor materials use)
Applying green chemistry to nanomaterials and nanomanufacturing Higher performance Cheaper More convenient Greener Green chemistry applied to nanoscience: Design nanomaterials that provide new properties and performance, but do not pose harm to human health or the environment Manufacture complex nanomaterials efficiently, without using hazardous substances Assemble/interface nanomaterials using bottom-up approaches and selfassembly to enhance performance and reduce waste McKenzie and Hutchison Green nanoscience, Chemistry Today, 2004, 30.
Applying the 12 principles to nanoscience Adapted from Dahl, J.A.; Maddux, B. L. S.; Hutchison, J. E. Toward Greener Nanosynthesis, Chem. Rev., 2007, In press.
Applying the 12 principles to nanoscience
Applying the 12 principles to nanoscience
Example 1: A greener synthesis of a key nanoparticle building block ethanol AuCl(PPh 3 ) C 6 H 6 B 2 H 6 PPh 3 HAuCl 4 + PPh 3 NaBH 4 (10 eq) toluene/water/toabr (1 eq) Using the new method: Safer, easier Schmid, preparation G.Inorg. Synth. 1990, 27, 214. Eliminates >600 cu. ft. of diborane/pound of NPs and 1,100 pounds of benzene /pound of NPs Rapid synthesis of gram quantities Cheaper (~ $500/g vs. $300,000/g ) Ph 3 P Cl Ph 3 P Au-TPP Cl Cl PPh 3 PPh 3 Narrow dispersity (d = 1.5 +/- 0.4 nm) PPh 3 Weare, Reed, Warner, Hutchison J. Am. Chem. Soc. 2000, 122, 12890. Hutchison, et al. Inorg. Syn. 2004, 34, 228.
Example 2: Greener purification of functionalized nanoparticles Nanomaterials purification Traditional: 15L solvent per gram NP 3 days work Diafiltration: No organic solvent (eliminates > 10,000 pounds/pound NPs ) 15 minutes work Diafiltration reduces solvent consumption and provides cleaner, well-defined building blocks Sweeney, Woehrle, Hutchison J. Am. Chem. Soc. 2006, 128, 3190.
Where has purity influenced performance? Optical Synthesize Nanoparticles Electronic Properties Toxicology Redesign Material Structure Function Assess Properties = Monodispersity Purity Functionalization Self Assembly Diafilter Thiol
Example 3: Biomolecular Nanolithography SiO 2 TEM Grid silanize n-octyltrichlorosilane DNA Solution Molecular Combing 20µm Pulled DNA Bensimon et al. Science 1994, 265, 2096. Incubate with nanoparticles Kearns et al. Anal. Chem. 2006, 78, 298-303; Warner et al. Nature Mater., 2003, 2, 272-277.
Assembling from the bottom up offers green chemistry advantages + Eliminates processing steps Incorporates more raw materials in product Reduces water and solvent use Provides access to smaller structures Greener - Higher performance - Cheaper - More convenient
Research Needs - Part 1 1. Structure-Activity Relationships to predict biological impacts, ecological impacts and degradation at end-of-life - need diverse populations of nanostructures for investigation, must have well-defined structures and purity profiles 2. New transformations and reagents that are more efficient, safer, and useful in a wider range of reaction media/solvents - must produce materials of high quality and purity and allow one to access the composition, size, shape, and functionality - must be scaleable. 3. Improved understanding of product distributions, nanoparticle formation mechanisms, and reaction stoichiometries - to assess atom economy, develop new synthetic and purification methods 4. Analytical techniques that permit the routine analysis of nanoparticles - real-time, in situ monitoring to optimize production processes, minimizing waste and energy costs, provide mechanistic information
Research Needs - Part 2 5. Alternatives to surfactants, templates, or other auxiliary substances to stabilize and control nanoparticle shape during synthesis - incorporate shape-controlling molecule as a function component of final product 6. Alternative solvents and reaction media - requires assessment to determine the implications with respect to chemical and energy utilization associated with production and use of the new reaction media. 7. Convenient purification methods that provide access to pure nanomaterials without generating large amounts of solvent waste 8. Metrics to compare the greenness of competing approaches that consider the relative hazards and efficiencies across the life cycle Adapted from Dahl, J.A.; Maddux, B. L. S.; Hutchison, J. E. Toward Greener Nanosynthesis, Chem. Rev., 2007, In press.
Designing safer nanoparticles Anticipate broad application (and distribution) in medicine, cosmetics, environmental remediation Nanomaterial synthesis Redesign Material Test Properties Structure/Property Relationships Diverse libraries Precisely engineered materials Appropriate bioassays
A diverse family of functionalized nanoparticles has been prepared for 1.5-nm (and 0.8-nm) core sizes R = ) 17 CH 3 ) 15 CH 3 ) 11 CH 3 ) 9 CH 3 ) 8 CH 3 ) 7 CH 3 ) 5 CH 3 CH 3 Si(OMe) 3 SO 3- Na + ) 3 SO 3- Na + N + HMe 2 Cl - N + Me 3 Cl - O(CH 2 N + Me 3- OTs O(CH 2 ) 2 O(CH 2 N+ Me 3- OTs O(CH 2 ) 2 O(CH 2 N+ Et 3- OTs -CH 2 COO - Na + COOH ) 11 COOH OH PO(OH -[(CH 2 O] 2 (CH 2 OH O(CH 2 OH -[(CH 2 O] 2 CH 2 COOH -(CH2)2COGlyGlyOH CONH(CH 2 ) 14 CH 3 OH Solubility Interparticle spacing Functionality J. Am. Chem. Soc. 2005, 127, 2172 and Inorg. Chem. 2005, 44, 6149
Scaling? Nanoparticle production in integrated microreactor systems? Rapid mixing Precise process control In situ monitoring Facile scale-up Reduced waste Improved yields New precursors and approaches Point-of-use production
Microcapillary system for continuous production of NPs Continuous flow system for Au11(PPh3)8Cl3 synthesis At least 10-fold increase in production rate (g/hour) At least five-fold decrease in solvent waste
Green nano in action PPh 3 Ph 3 P Cl Au-TPP Cl PPh 3 PPh 3 Ph 3 P Cl PPh 3 Synthesis/production Purification Customization Higher performance Bottom-up Assembly Less hazard Less waste Lower cost
Green chemistry - A driver for innovation?
Acknowledgements Greg Kearns Evan Foster Lallie McKenzie Mike Jespersen Scott Sweeney Shuji Goto Dr. Marvin Warner Dr. Gerd Woehrle Dr. Scott Reed Dr. Leif Brown Walter Weare Shinichi Uesaka Support: National Science Foundation; Dreyfus Foundation; Sloan Foundation; SONY Corporation; Air Force Research Laboratory; ONAMI