Liquid droplets atop both isotropically and anisotropically patterned substrate surfaces are investigated experimentally. The patterns are realized by means of elastic wrinkling/buckling of a thin layer of gold coated atop polystyrene shape memory polymer. Static contact angles are measured, and images showing the shapes of droplets are captured. The results obtained from isotropically patterned substrates suggest that surface roughness has no apparent effect on the static contact angles in this study. However, atop anisotropically patterned substrates, both the static contact angles and shapes of droplets vary with the direction of wrinkles and size of droplets.
SharpeR. B. A.BurdinskiD.HuskensJ.ZandvlietH.J.W.ReinhoudtD.N.PoelsemaB.Spreading of 16-mercaptohexadecanoic acid in microcontact printing. Langmuir, 2004, 20, 8646–8651.
2.
YangY.-S.KimH.-Y.ChunJ.-H.Spreading and solidification of a molten microdrop in the solder jet bumping process. IEEE Trans. Compon. Packag. Technol., 2003, 26, 215–221.
3.
KimC.KangS. C.BaldwinD. F.Experimental evaluation of wetting dynamics models for Sn63Pb37 and SnAg4.0Cu0.5 solder materials. J. Appl. Phys., 2008, 104, 1–13 033537.
4.
YangA.-S.YangM.-T.HongM.-C.Numerical study for the impact of liquid droplets on solid surfaces. Proc. IMechE, Part C: J. Mechanical Engineering Science, 2007, 221, 293–301 DOI: 10.1243/0954406JMES488.
5.
YoshimitsuZ.NakajimaA.WatanabeT.HashimotoK.Effects of surface structure on the hydrophobicity and sliding behavior of water droplets. Langmuir, 2002, 18, 5818–5822.
6.
MoritaM.KogaT.OtsukaH.TakaharaA.Macroscopic-wetting anisotropy on the line-patterned surface of fluoroalkylsilane monolayers. Langmuir, 2005, 21, 911–918.
7.
PrabhuK. N.FernadesP.KumarG.Effect of substrate surface roughness on wetting behaviour of vegetable oils. Mater. Des., 2009, 30, 297–305.
8.
DrelichJ.The effect of drop (bubble) size on contact angle at solid surfaces. J. Adhes., 1997, 63, 31–51.
9.
DrelichJ.MillerJ. D.HupkaJ.The effect of drop size on contact angle over a wide range of drop volumes. J. Colloid Interf. Sci., 1993, 155, 379–385.
10.
DrelichJ.MillerJ. D.KumarA.WhitesidesG. M.Wetting characteristics of liquid drops at heterogeneous surfaces. Colloids Surf. A Physicochem. Eng. Asp., 1994, 93, 1–13.
11.
DrelichJ.MillerJ. D.GoodR. J.The effect of drop (bubble) size on advancing and receding contact angles for heterogeneous and rough solid surfaces as observed with sessile-drop and captive-bubble techniques. J. Colloid Interf. Sci., 1996, 179, 37–50.
12.
AmirfazliA.NeumannA. W.Status of the three-phase line tension. Adv. Colloid Interf. Sci., 2004, 110121–141.
13.
BrandonS.HaimovichN.YegerE.MarmurA.Partial wetting of chemically patterned surfaces: The effect of drop size. J. Colloid Interf. Sci., 2003, 263, 237–243.
14.
BliznyukO.VereshchaginaE.KooijE. S.PoelsemaB.Scaling of anisotropic droplet shapes on chemically stripe-patterned surfaces. Phys. Rev. E, 2009, 334, 041601.pp. 1–6.
15.
ShikhmurzaevY.Moving contact lines in liquid/ liquid/solid systems. J. Fluid Mech., 1997, 334, 211–249.
16.
FanH.Liquid droplet spreading with line tension effect. J. Phys. Condens. Matter, 2006, 18, 4481–4488.
17.
XuL.FanH.YangC.HuangW. M.Contact line mobility in liquid droplet spreading on rough surface. J. Colloid Interf. Sci., 2008, 323, 126–132.
18.
LiuN.HuangW.M.PheeS.J.TongT.H.The formation of micro-protrusions atop a thermo-responsive shape memory polymer. Smart Mater. Struct., 2008, 17, 057001. pp. 1–6.
19.
VolynskiiA. L.BazhenovS.LebedevaO. V.BakeevN.F.Mechanical buckling instability of thin coatings deposited on soft polymer substrates. J. Mater. Sci., 2000, 35, 547–554.
20.
GenzerJ.GroenewoldJ.Soft matter with hard skin: From skin wrinkles to templating and material characterization. Soft Matter, 2006, 2, 310–323.
21.
BowdenN.BrittainS.EvansA. G.HutchinsonJ. W.WhitesidesG. M.Spontaneous formation of ordered structures in thin films of metals supported on an elastomeric polymer. Nature, 1998, 393, 146–149.
