Introduction to Nanoscience & Molecular Engineering (NME) René M. Overney Department of Chemical Engineering University of Washington Seattle, Washington 98195 [email protected] http://depts.washington.edu/nanolab/ R.M. Overney University of Washington Birth of Interfacial and Molecular Sciences • Colloid Science (early 1800s) Products: Aerosols of liquid droplets or solid particles Foams Emulsions Sols or suspensions Micelle Solid foams, emulsions or suspensions a surfactant aggregate Thomas Graham • Surface Science (early 1900s) Sub-disciplines: Surface Chemistry Surface Physics Analytical Techniques Irvin Langmuir & Katharine Blodgett 1 R.M. Overney University of Washington Colloidal Process: Flocculation Water Purification: 1) Addition of calcium chloride and flocculation agent 2) Initiation via shear Flocculation of a clay suspension bridging flocculation Commercial flocculant: Muddy Water polyacrylamide-random- (acrylic acid) copolymer Bob Gilbert (University of Sydney, Australia) R.M. Overney University of Washington Functional Materials With increasing sophistication in molecular synthesis, material could be designed from the “bottom-up” for specific applications. Functional Materials Definition: Materials of rational molecular design tailored towards specific - electronic (i) from macro- molecules - magnetic (iii) to devices - optical Electro-Optical (E-O) Switches - thermal (ii) with unique structures and - mechanical Properties if “assembled” or other properties, to attain performance matrices that are/were conventionally unattainable are referred to as functional materials. 2 R.M. Overney University of Washington Bottom-up Approach Inorganic material synthesis from atoms by means of “atomistic self-assembly”. • Molecule: Ultra-small clusters: 10 – 100 atoms show strongly deviating molecular structures from the bulk. Si13 E.g.: Si13 (metallic-like close packing) Si45 (distorted diamond lattice) • Quantum Dot: Small clusters: ~103 -106 atoms (bulk-like structure) but possess discrete excited electronic states if cluster diameter Si45 less than the bulk Bohr radius, ao, (typically < 10 nm) 2 U. Rothlisberger, et al., ⎛ h ⎞ Phys. Rev. Lett. 72, ⎜ ⎟ π 665 (1994). = ⎝ 2 ⎠ ao 2 me R.M. Overney University of Washington Molecular Self-Assembly involving organic materials Lipid Bilayer (LB Technique) Self-assembly of C18ISA on on silicon oxide surface HOPG surface R.M. Overney, Phys. Rev. Lett. 72, 3546-3549 (1994) S. De Feyter et al. in Organic Mesoscopic Chemistry, Ed. H. Masuhara et al., Blackwell Science 1999 3 R.M. Overney University of Washington Birth of Nanoscience and Nanotechnology Seeing makes believing: The invention of the Scanning Tunneling Microscope (STM) in Zurich (Switzerland) in 1981 marked the birth of nanoscience and nanotechnology. Nobel Prize in Physics 1986 The prize was awarded by one half to: ERNST RUSKA for his fundamental work in electron optics, and for the design of the first electron microscope. GERD BINNIG and HEINRICH ROHRER for their design of the scanning tunneling microscope. G. Binnig H. Rohrer Quantum Choral Xenon Atoms on Nickel Surface (D.M. Eigler et al., IBM Almaden) R.M. Overney University of Washington Scanning Probe Microscopy (SPM) – the Nanoscience Tool Tools that operate in real space with Ångstrom to nanometer spatial resolution, in contrast to scattering techniques, such as for instance the SEM (scanning electron microscope), that operate in the reciprocal space. In principle, SPM systems consist of Probe Sensors that are nanosized (accomplished microlithographically), SPM Probe Scanning and Feedback Mechanisms that are accurate to the subnanometer Feedback Field or level (achieved with piezoelectric Signal Perturbation material), and Sample Highly Sophisticated Computer Piezo Material Controls (obtained with fast DACs Scanner (digital analog converters, etc.). 4 R.M. Overney University of Washington Scanning Force Microscopy (SFM) - the most widely used SPM system Photodiode LASER Topography PIEZO Friction CANTILEVER 100 µm SAMPLE A 32.33 µm 50 µm B 16.17 µm 0 µm 0 µm 50 µm 100 µm 0 µm Tg = 374K 0 µm 16.17 µm 32.33 µm Material Distinction Elasticity Glass Transition SFM R.M. Overney University of Washington Nanoscience and Molecular Engineering Molecular Sciences Nanoscience Surface Sciences and T e c h n o l o g i e s NanoScience & Molecular Engineering - Cognitive engineering based on molecular designs and external constraints. • Health • Materials Expectations/Impact: • Energy • Environment • Consumer goods 5 R.M. Overney University of Washington Nanoscience and Molecular Engineering NME Achieve a fundamental understanding of Engineering Molecular and Nanoscience Internal Constraints External Constraints and utilize this knowledge Nanoscience towards a cognitive Inter- & Intra-Molecular Constraints Interfacial & Dimensional Constraints Fundamental Material Design Strategy Involving Constraints on the Molecular- and Nano- Scale to impact Nanoscale Processes Molecular Engineering Molecular & Novel Device Technologies R.M. Overney University of Washington Nanoscience and Molecular Engineering ~ 2000 ~ 2025 Dalton, Jen, Overney (UW) Mike Rocco (NSF), AIChE Journal, Vol. 50, 2004 6 R.M. Overney University of Washington Modern Technology - Engineering with Constraints - Engineering Applications - External Constraints To p – Do wn Membranes L ith og Fuel Cell rap hy HardDrive TeraBit Lubrication Recording - Inter- and Intramolecular Energetics ln(aT) Constraints ()x ( )y Bottom - Up Δ FF PS-CLD1#24.2kcal/mol Cooperativity O OO O O O F ( ) H3C N 3 F ( vo(T1) , FF,max(T1) ) F O F F F F F O O T1 F O F O CN T F O 2 O O CN Gray, Nano Lett. NC 14.5kcal/mol Self - Assembly 8, 754 (2008) ln(v) ln(v) S. Sills, PRL 91(9), 095501, 2003 R.M. Overney University of Washington Inter- and Intramolecular Constraints Example: Organic Self-Assembling Molecular Glasses Objective: Supramolecular interactions TΔS * to create long-range molecular order large Ph-PhF 3D Quadrupolar Network ΔG* = ΔH * −TΔS * = o + Δ * Ea Ea T S TΔS * ΔF ≈ − F φ' Face-to-Face Arene/Pentafluorophenyl Interactions Anthryl phenyl IFA Stabilization Energy Stabilization Energy E = 4-6 kcal/mol E = 7.3 kcal/mol D. Knorr, et al., J. Phys. Chem. B, 113, 14180-14188 (2009) 7 R.M. Overney University of Washington External Constraints - Interfacial Constraints Dewetting Velocity - Field Constraints/Gradients ~ 100 nm Overney, J. VST B 14, (1996) 0 100 200 300 400 500 PEP thickness [nm] Glass Transition Glass Interfacial Cooling ~ 2 nm M. He, PRL (2000) S. Sills, Chem. Phys Lett. 120, 5334(2004) - Dimensional Constraints Polymer Nanorods Size Selective Spontaneous precursor film Sorption Selective ~ 10 nm 3.0 Low viscosity precursor 2.8 N Before 2 N After 2.6 2 He Before t1 t2 He After 2.4 CO2 Before CO After 2 2.2 t0 Pressure (cm Hg) High viscosity precursor 2.0 0 5000 10000 15000 20000 25000 Gas Permeation t2 t1 Time (s) R.M. Overney University of Washington NME Research in Overney’s Lab Interfacial and Dimensional Intra- and Intermolecular Constraints Constraints Fundamentals – Side-chain and local backbone – Relaxations, glass transition, relaxations, critical energy barriers crystallization (polymers) – Self-assembly – Molecule-molecule interaction during – Glass forming process structuring process (molecular glasses) – Local mass transport properties – Cooperativity and energy consumption, (membranes) cooperative length scale –… –… – Condensed organic materials – Ultrathin polymer films Materials – Polymers (polyelectrolytes, conjugated – Membranes polymers, dendritic-chromophore – Nanocomposites polymers, …) – Organic LED materials – Molecular glasses – Simple alkane liquids – Organic NLO materials –… –Proteins –… – Understanding phenomenological – LED spectral stability Impact properties and processes (e.g., glass – Material phase control (amorphous vs. transition) crystalline) – Origin of frictional energy dissipation – Low frictional dissipation interfaces – Cognitive approach to material – Origin for transport properties (e.g., engineering (e.g., towards increase in PEM fuel cells, reverse selective electro-optical activity in photonics) membranes) –… –… 8 R.M. Overney University of Washington Minor in Nanoscience and Molecular Engineering (NME) NSF 0938558 Undergraduate Minor in Nanoscience and Molecular Engineering in departments across CoE and CoA&S http://depts.washington.edu/nanolab/NUE_NME/NUE_NME.htm Minor in Nanoscience and Molecular Engineering NME Mission Statement To establish an undergraduate, discipline- tailored Minor in Nanoscience and Molecular Engineering within the University of Washington’s College of Engineering (CoE) and College of Arts and Sciences (CoA&S) with integration of the wider community that empowers students for subsequent workforce or educational advancement. 10/2009 http://depts.washington.edu/nanolab/NUE_NME/NUE_NME.htm R.M. Overney 9 Minor in Nanoscience and Molecular Engineering NME Current Stakeholders UW Stakeholders Colleges: Engineering (CoE) Arts & Sciences (CoA&S) Departments: BioEngineering (BioE) Chemical Engineering (ChemE) Chemistry (Chem) Electrical Engineering (EE) Mechanical Engineering (MechE) Materials Science & Engineering (MSE) Physics (Phys) Centers: Center for Nanotechnology (CNT) Gen Eng Mat Sci & Eng Cntr (GEMSEC) Community Stakeholders: Edmonds Community College (EdCC) North Seattle Community College (NSCC) 10/2009 http://depts.washington.edu/nanolab/NUE_NME/NUE_NME.htm R.M. Overney Minor in Nanoscience and Molecular Engineering Example: Minor