1. Superwetting nanowire membranes for selective absorption Authored by Jikang Yuan, Xiaogang Liu, Ozge Akbulut, Junqing Hu, Steven L. Suib, Jing Kong and Francesco Stellacci Presented by Bryce Smith, Neal Mistry, Elliot Young, and Kyle Hamaker

2. Problem ●Need new ways to combat water pollution o Oil spills o Industrial pollution o Water contaminants Source: http://www.freedrinkingwater.com/images-new/education-page/image/algae-lake.jpg

3. Purpose Construction method of nanoporous membranes for: ●Catalyst Supports ●Filters for Biomolecule Purification ●Seawater desalination Construct a nanowire membrane that is: ●thermally stable ●controlled wetting behaviour ranging from superhydrophilic to superhydrophobic

4. What has been done? BP Oil Spill - Chemical Dispersants ●Breaks down oil into smaller droplets Magnets and Nanotechnology ●water-repellent nanoparticles that contain iron Cloth Coated with Chemical Polymer ●both hydrophilic and oleophobic http://upload.wikimedia.org/wikipedia/commons/6/61/C- 130_support_oil_spill_cleanup.jpg

5. Image: Yuan, J., Laubernds, K., Villegas, J., Gomez, S. & Suib, S. L. Spontaneous formation of inorganic paper-like materials. Adv. Mater. 16, 1729–1732 (2004). ●3D porous nanostructures ○capillary action ● Oleophobic ●Cryptomelane pore size = 10nm, 44 m 2 g -1 Procedure 1:2:1 ●Manganese Oxide Autoclave manganese sulfate, potassium sulfate, potassium persulfate DI water Teflon

6. Procedure ●Coating of silane = superhydrophobic o Vapor deposition Polydimethysiloxane (PDMS) Cooling 234°C, 30min Heating 390°C Silicone coating Image: Barron, Andrew R. "Chemical Vapor Deposition." OpenStax CNX. Rice University, n.d. Web. 21 Sept. 2014.

7. Non-Coated Membrane a)Optical image of membrane b)SEM image of cross-sectional area c)SEM image of surface morphology of membrane d)SEM image of nanowire networks e)Close up SEM of nanowire bundle f)TEM of single cryptomelane nanowire g)Close-up view of f) h)Wetting time vs. # water droplets deposited over a time interval Figure adapted from reference 1.

8. Water contact angle Figure adapted from http://www.funsci.com/fun3_en/exper2/exper2.htm

9. Silane-coated membrane Figure adapted from reference 1 a)Water contact angle b)SEM image of nanowires coated in silicone c)TEM image of modified nanowires d)High-magnification TEM image of silicone coating on nanowire e)EDS spectrum Cryptomelane: K(Mn 4+,Mn 2+ ) 8 O 16 PDMS: (C 2 H 6 OSi) n

10. Surface wetting switchability Figure adapted from reference 1 a)Representation of reversible wettability b)Contact angle and hysteresis measurements taken after each transition cycle

11. Wettability a)Absorption capacities for different organic solvents and oils b,c)Layer of blue-dyed gasoline being removed by membrane Figure adapted from reference 1

12. Analysis ●Wettability is highly switchable ●Mechanically robust - resists repeated ultrasonic treatment ●Silane coating not the only reason for superhydrophobic behavior ●Highly effective selective superabsorbance ●Reusable

13. Applications 1.Removal of oil from water in case of oil spills 2.Detection of solutes with similar polarities in a solution http://www.safety4sea.com/ship-execs-in-trouble-over-oil-spill-13790

14. Oil Spill ●Absorbs oil while leaving water behind ●Using ultrasonic washing, the membrane releases the oil and allows for reuse of both oil and material

15. Chromatography The massive surface area of the nanotube membrane magnifies the difference in polarity of similar solutes in a solution Leads to better detection of pollutants

16. Example Solutes TOLUENE BENZENE http://iaspub.epa.gov/tdb/pages/contaminant/contaminantOverview.d o?contaminantId=10140 http://commons.wikimedia.org/wiki/File:Toluene.png

17. Chromatography Data Figure adapted from Reference 1

18. References 1.Yuan, Jikang, Xiaogang Liu, Ozge Akbulut, Junqing Hu, Steven L. Suib, Jing Kong, and Francesco Stellacci. Superwetting Nanowire Membranes for Selective Absorption (2008): 332-36. Web. 19 Sept. 2014. 2.Barron, Andrew R. "Chemical Vapor Deposition." OpenStax CNX. Rice University, n.d. Web. 21 Sept. 2014. 3. Levitt, Tom. "Cleaning up Oil Spills with Nanotechnology and Magnets." CNN. CNN, 21 Sept. 2012. Web. 21 Sept. 2014. 4.Rutherglen, Chris, Dheeraj Jain, and Peter Burke. "Nanotube Electronics for Radiofrequency Applications." Nature.com. Nature Publishing Group, 29 Nov. 2009. Web. 19 Sept. 2014. 5."Seven Technologies Used to Clean the Gulf Oil Spill." CBSNews. CBS Interactive, 5 May 2010. Web. 21 Sept. 2014.