Great Lakes Webinar. Marty Mulvihill July 11 th A Greener Approach to Nanotechnology

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1 Great Lakes Webinar Marty Mulvihill July 11 th 2012 A Greener Approach to Nanotechnology

2 Sustainability and Green Chemistry Sustainability Meeting the needs of the present without compromising the ability of future generations to meet their needs Our Common Future, Report of the Brundtland Commission, Oxford University Press 1987 Green Chemistry Sustainability at the molecular level The science behind the discovery and implementation of safer, cleaner, and more efficient chemical processes and products Entails design of chemical products and processes that aim to eliminate the use and generation of hazardous substances Seek to minimize: Waste Energy use Resource use (maximize efficiency) Use renewable resources Berkeley Center for Green Chemsitry

3 Natural Synergy between Green Chemistry and Nanotechnology Dematerialization and Transmaterialization use less Cradle to Cradle thinking Mulvihill, et al. Annu. Rev. Environ. Resour : Berkeley Center for Green Chemsitry

4 Horizontal technologies Nanotechnology and Green Chemistry Water Energy Health Food Berkeley Center for Green Chemsitry

5 What would Green Nanotechnology look like? 1. Green Process 2. Green Product JEAN FRANCOIS PODEVIN, Berkeley Center for Green Chemsitry

6 Room for Improvement in nanotechnology Process Eckelman. et al, J. Indust. Ecol. 2008, 12, 316. Berkeley Center for Green Chemsitry

7 Principles of Greener Nanoscience Hutchison, J. et al, Chem. Rev. 2007, Berkeley Center for Green Chemsitry

8 Greener and safer products Mohit Joshi, Berkeley Center for Green Chemsitry

9 Modes for Biological Interaction Andre Nel, et al. Science 311, 622 (2006);

10 Modes for Cellular Uptake Diffusion-Passive Transport Perforation-Cytoxic Active Transport Endocytosis

11 How are we going to get there? BUSINESS AND GOVERNMENT Policy Public Health Business UNIVERSITY Chemistry Engineering Identify Opportunities Use Greener Materials and Methods Evaluate Progress Emerging Concerns Characterized Concerns Toxicology Environmental Science Public Health Everyone will Contribute Berkeley Center for Green Chemsitry

12 Berkeley Center for Green Chemistry: A life Cycle Approach College of Engineering Developing more efficient processes Hass School of Business Characterizing the Business drivers Labor and Occupational Health Program Implementing understanding College of Chemistry Using more efficient and less impactful chemicals & process School of Public Health and Toxicology Ensuring safer materials selection College of Natural Resources Understanding the impacts of chemical products on the environment Berkeley Center for Green Chemsitry 11

13 Three Examples of Greener Nanoscience Synthesis Environmental Sensing Environmental Stability Berkeley Center for Green Chemsitry 12

14 Example 1: Arsenic Sensor Development Both chronically and acutely poisonous million people are exposed to Arsenic levels of 10 ppb or greater. Need for rapid detection. Meeting the needs of the present. Berkeley Center for Green Chemsitry

15 Surface Enhanced Raman Spectroscopy Traditional Raman Scattering Surface Enhanced Raman Scattering hv O As HO O O hv arsenate stretching energy Concentrates light near analytes. SERS Enhancements EF = (I surface )/(I solution ) x N solution /N surface Only 1 in 100,000,000 photons Typical Enhancement Factors (EF) for non-resonant analytes are Detection limits ~100 ppm. Berkeley Center for Green Chemsitry 2012 Detection limits in ppb (10-8 M) or even ppt (10-10 M) range. 14

16 Making a Good SERS Substrate Field Enhancement at sharp corners Field Enhancement particle junctions Halas et al. Nano Letters 2005, Naumov, I. et al. Applied Physics Letters 2010, Berkeley Center for Green Chemsitry

17 Chemically Induced Shape Control Ag(NO 3 ) + Ag o + HNO 3 + A.Tao et al, Angewandte 2006, Berkeley Center for Green Chemsitry

18 What Makes This Green Chemistry? One-pot synthesis. Tunable reaction. No purification needed. Moderate temperatures: 190 o C Benign capping agent: PVP Reasonably safe reagents and solvents. E-factor: 105 (320 with purification) Still room for improvement, but a good start. Berkeley Center for Green Chemsitry

19 Shape Dependent Properties Scanning Electron Microscopy (SEM) Particle Morphology Darkfield Optical Microscopy Particle color UV-Vis Spectroscopy Particle Absorption. Berkeley Center for Green Chemsitry

20 Langmuir Blodgett Assembly Increasing Surface Pressure High surface area Control over packing density A. Tao, et. al, Nat. Nanotech. 2008, Berkeley Center for Green Chemsitry

21 The Arsenic Sensor Laser Water Nanoparticles As(V) As(III) As(V) PVP SO 4 PO 4 PVP Berkeley Center for Green Chemsitry

22 Sensing at ppb in ground water Shape Effect Both Shape and PVP improve the sensitivity of particle assemblies. M. Mulvihill, Angew. Chem. Int. Ed. 2008, Berkeley Center for Green Chemsitry 2012 Sensitivity Linear over three orders of magnitude. Well below WHO limits. 21

23 A recipe for improvement? 1 parts 30% H 2 O 2 5 parts conc. NH 4 OH 0.08 parts CrO 3 in HCl Etches pits in dislocations on (111) and (100) silver surfaces Levinstein and Robinson, Journal of Applied Physics. 1962, Berkeley Center for Green Chemsitry

24 Selective, but not interesting The diagonal of the resulting 150 nm cube is about 270 nm, which is the face to face distance in the starting octahedra. Berkeley Center for Green Chemsitry

25 Improved Selectivity and Sustainability To determine the driving force of the reaction: ΔG = -nfe. H 2 O 2 + 2H + + 2Ag NH 3 OH + 2H + + 2Ag 2Ag + + 2H 2 O 2Ag + + NH H 2 O E = V E = V CrO H 2 O + 3Ag 3Ag + + Cr(OH) 3 + 5OH - E = V The CrO 3 was removed and the etching improved. M. Mulvihill, JACS. 2010, 268. Berkeley Center for Green Chemsitry

26 Chemically Induced Shape Control H 2 O 2 + 2H + + 2Ag NH 3 OH + + 2H + + 2Ag 2Ag + + 2H 2 O NH Ag + + H 2 O Berkeley Center for Green Chemsitry

27 Improved Sensing Berkeley Center for Green Chemsitry

28 Sensing on a single Nanoparticle Benzene thiol 20mM in EtOH Drop Cast Map Berkeley Center for Green Chemsitry

29 What Makes This Green Chemistry? 1 Continual Improvement 2 Safer Starting Materials 3 Self Assembly 4 Efficient Material utilization Berkeley Center for Green Chemsitry

30 Implications of Nanotechnology 1. Large market 2. New properties 3. Unknown impacts on health 4. Unknown impacts on the environment 5. Lack of regulation Berkeley Center for Green Chemsitry

31 Fate of Nanoparticles Nanoparticle Characteristics Size between nm Molecular weights very high 100,000 1,000,000 g/mol Vapor pressure not relevant Aerosols need to be characterized. Water/soil partitioning will depend on surface coatings Water transport depends on stability of nanoparticle suspensions Berkeley Center for Green Chemsitry

32 Influence of Nanoparticle Shape Berkeley Center for Green Chemsitry

33 Surface Coating Characterization MUA MHA MPA Surface charge density is 35 (±5) mv for all particles. Surface charge density is 35 (±5) mv for all of the carboxylic acid ligands. Berkeley Center for Green Chemsitry

34 Aggregation Rates for Various Shapes Berkeley Center for Green Chemsitry

35 Shape and Surface Area Nanoparticle surface area is directly related to CCC. This predicts greater stability for 1-D and branched materials. Supports the primary role of electrostatic screening for NP stabilization. M. Mulvihill, Chem Mater. 2010, Berkeley Center for Green Chemsitry

36 Effect of Surface Coating Berkeley Center for Green Chemsitry

37 Ligand instability Ligand shells are dynamic Shorter chain ligands are less stable + k 11 -k 11 Berkeley Center for Green Chemsitry

38 Excess Ligands Stabilize Particles CCC can be controlled with the addition of excess ligand. M. Mulvihill, Chem Mater. 2010, Berkeley Center for Green Chemsitry

39 Conclusions Shape and Size Surface area is the most important predictor of stability Surface Coating Ligand binding is dynamic Longer chain ligands lend stability Berkeley Center for Green Chemsitry

40 What Makes This Green Chemistry? Basic science to help Design for degradation Design safer materials Berkeley Center for Green Chemsitry

41 Acknowledgements Advisers- John Arnold & Peidong Yang Collaborators- Andrea Tao, Jean Benjauthri, Joel Henzie, Xing Yi Ling Advisers- Jamin Wan and Taleb Mokari Collaborators- Emory Chan, Susan Habas, Delia Millron, Yongman Kim, Saeed Torkzaban, Tetsu Tokunaga Collaborators- John Arnold, Meg Schwarzman, Mike Wilson, Alastair Iles, Chris Vulpe, Chris Rosen, Avi Ringer, Akos Kokai Berkeley Center for Green Chemsitry

42 Thank You! Berkeley Center for Green Chemsitry