Student Project Abstracts 2005 - Pluto - University of Washington

throughout the work period. Five surfaces were angles and a continuous water flux for dynamic angle measurements for all diamond surfaces wasnanocrystalline, had a thickness range of about 2- contact angles were manipulated using a water between 71°-90°. The range of contact anglehysteresis for all diamond surfaces was quite3 m, and had diamond grain in the scale ofsyringe suspended above the platform. Thelarge, between 8°-74°. The range of grain density100nm. The nanocrystalline surfaces were grown syringe was attached to an apparatus on the for CAM all diamond surfaces was between 7-15 m -2 ;CONTACT ANGLE MEASUREMENTS ON DIAMOND SURFACESthe range forFORroughnessAwasSTUDYbetween 5.2-41nm.with varying concentrations of methane, which that would allow for adjustment in height of theON HYDROPHOBIC FORCESgrain density recording.affected the grain size. The other four surfacessyringe by a winding, spindle-like metal rod.were two by polycrystalline a winding, disks, spindle-like having a metal rod.DynamicDynamiccontactcontactangle measurementsanglewerethickness of around 180 m and totaling 11mm recorded by adjusting the metal platform so thatin diameter. measurements Both sides of the were polycrystalline recorded by adjusting the water the syringe metal was nearly platform touching a samplesurfaces so were that used the for research; water syringe one side wassurface. Therefore, the water flux could be betterwas nearly touching a sample surface.deemed smoother due to being polishedadjusted so that a droplet could grow or shrink formechanically Therefore, before being the sent water for flux this particular could be better advancing adjusted contact so that angle a and droplet receding contactresearch could use. The grow nanocystalline or shrink surfaces for wereangle measurements, respectively. After takingadvancing contact angle and recedingsignified from al25-al29, and the polycrystalline an image of a single water droplet, camera framessurfaces contact sd1u, sd1d, angle sd2u, and measurements, sd2d, respectively. respectively. and corresponding After taking data were an image exported from theCAM software into Microsoft Excel software toof a single water droplet, camera frames and corresponding dataProcedureplot graphs and chart pertinent data. The samewere Contact exported angle measurements from the were CAM taken software format into Microsoft was followed Excel for multiple softwareto plot graphs and chart pertinent data. The same formatimages of ausing a CAM 100 contact angle machine with a water droplet growing or shrinking on a sample50mm USB camera. For static contact anglesurface.measurements, the metal platform of the machinewas followed for multiple images of a water droplet growing orshrinking on a sample surface.The grain density and roughness wereinadvertently omitted for all the polycrystallinesamples except one, surface sd1u, which had aroughness of sample recording of 5.2 nm sans aWater syringe placing water droplet on sample surfaceWater syringe placing water droplet on sample surfaceANALYSISGenerally, advancing and receding contact angle graphs followedthe definition described previously. The peaks for contactangles and plateaus for baseline length were observed accordingly.The average range of advancing contact angle measurements forall diamond surfaces was between 70°-89°; the range of advancingbaseline lengths averaged between 3.8-5.2mm. The averagestandard error for advancing contact angles was around ± .394,and the average standard error for advancing baseline lengthswas around ± .002. The average range between receding contactangle measurements for all diamond surfaces was between 22°-66°; the range of receding baseline lengths averaged between 4.4-4.28mm. The average standard error for receding contact anglemeasurements was around ± 2.95, and the average standard errorfor receding contact angle measurements was around ± .14. Therange for static contact angle measurements for all diamond surfaceswas between 71°-90°. The range of contact angle hysteresisfor all diamond surfaces was quite large, between 8°-74°. Therange of grain density for all diamond surfaces was between 7-15μm -2 ; the range for roughness was between 5.2-41nm.The grain density and roughness were inadvertently omittedfor all the polycrystalline samples except one, surface sd1u,which had a roughness of sample recording of 5.2 nm sans a graindensity recording.RESULTS/CONCLUSIONSurface sd1u, as shown above, had the lowest recorded measurementfor roughness; it also had the lowest recorded measurementout of all the surfaces for contact angle hysteresis (8°). Generally, itwasResults/Conclusionobserved that the surfaces with high hysteresis seemed to haveGenerally,Generally,ititwaswasobservedobservedthatthatthethesurfacessurfaceswithwithSurfacehigh roughness Surface sd1u,sd1u,asasrecordings. shownshownabove,above,hadhadSurfaces thethewithhighhighhysteresishysteresishighseemedseemedroughnesstotohavehavehighhighrecordingsroughnessroughnesslowestlowestrecordedrecorded measurementmeasurementforforroughness;roughness;itit recordings.recordings.SurfacesSurfaceswithwithhighhighroughnessroughnessalsoalso seemedhadhadthethe lowestlowestto recordedrecordedhave measurementmeasurementhigh static outoutofofcontact recordingsrecordingsangle alsoalsomeasurements.seemedseemedtotohavehavehighhighstaticstaticcontactcontactall all the the surfaces for for contact contact angle angle hysteresis hysteresis (8°). (8°).Static Contact Angle of ofSurfaces(degrees)Static Contact Angle ofSurfaces(degrees)angle angle measurements.measurements.Roughness of of Surfaces Surfaces vs. vs. Static Static Contact ContactAngleAngleSeries1 Series18684al27 al27al28 al28828078sd1ual29 al2976al25 al25al26 al2674720 5 10 15 20 20 25 25 30 30 35 35 40 40 45 4586848280787674Roughness of of Surfaces(nRoughness of Surfaces vs. Static Contact Angleoosd1ual27 al27al29 al29720 5 10 10 15 15 20 20 25 25 30 30 35 35 40 40 45 45RoughnessRoughnessofofSurfaces(nSurfaces(nReferences[1][1]J.J. Israelachvili,Israelachvili,IntermolecularIntermolecular &SurfacesSurfacesForces,Forces,AcademicAcademicPress.Press.2 nd 2Ed., nd Ed.,20032003REFERENCESal25 al25al28 al28Series1al26 al26[1] J. Israelachvili, Intermolecular & Surfaces Forces, AcademicPress. 2 nd Ed., 200310 CMDITR Review of Undergraduate Research Vol. 2 No. 1 Summer 2005