Wetting of Composite Surfaces - American Chemical Society

Subscriber access provided by Otterbein University

Article

Wetting of Composite Surfaces: When and Why the Area Far from The Triple Line is Important?" Edward Bormashenko, and Yelena Bormashenko J. Phys. Chem. C, Just Accepted Manuscript • DOI: 10.1021/jp407171v • Publication Date (Web): 26 Aug 2013 Downloaded from http://pubs.acs.org on August 31, 2013

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

The Journal of Physical Chemistry C is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 20

The Journal of Physical Chemistry

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Wetting of Composite Surfaces: When and Why the Area Far from The Triple Line is Important?

Edward Bormashenko*, Yelena Bormashenko Ariel University, Physics Faculty, P.O.B. 3, 40700, Ariel, Israel

Corresponding author: Ed. Bormashenko E-mail: [email protected] Postal address: Ariel University, P.O.B. 3, 40700, Ariel, Israel Tel.: +972-3-9066134 Fax: +972-3-9066621

ACS Paragon Plus Environment


Page 2 of 20

2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract Apparent contact angles are totally governed by the area of solid surface adjacent to the triple (three-phase) line. However, apparent contact angles do not describe the wetting situation exhaustively. The wetting regime is characterized by both apparent contact angle and the energy of adhesion. The energy of adhesion in turn depends on the physical and chemical properties of the entire area underneath the droplet. We demonstrate this experimentally by preparing rough surfaces exhibiting high apparent contact angles accompanied with the high energy of adhesion leading to the high contact angle hysteresis. A droplet deposited axisymmetrically

on

the

superhydrophobic

surface

comprising

non-

superhydrophobic spot holds “sticky” wetting attended with high apparent contact angles. Keywords: apparent contact angle; energy of adhesion; Cassie wetting; Wenzel wetting; contact angle hysteresis; rose petal effect.


Page 3 of 20


3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Introduction The wetting of composite solid surfaces has been subjected to intensive and hot scientific discussion, started recently by Gao and McCarthy in their paper, entitled "How Wenzel and Cassie Were Wrong?" The discussion was concentrated on the question: is the wetting of a composite surface a 1D or 2D affair?1–12 In other words: is the wetting of a composite surface influenced by a total surface underneath the droplet, or only the area adjacent to the triple (three-phase) line is important? The use of the notions of “1D” and “2D” wetting scenarios needs care. The triple line is a physical object, hence it has certain thickness and width; the last was estimated experimentally recently as 2-5 µm.13-14 However, the use of these notions is justified for distinguishing of situations, when the wetting regime is governed by an area of substrate close to the triple line from those when it is dictated by an entire area underneath the droplet. An accurate variational treatment of the problem demonstrates explicitly that equilibrium apparent contact angles are influenced by the three-phase adjacent area of solid only.11 This prediction coincides with the experimental findings reported by Gao and McCarthy.1 The fact that apparent contact angles are governed by physical and chemical peculiarities of the solid surface close to the triple line may lead to the misleading conclusion that wetting of composite or rough surface is exhaustively characterized by considering the solid area in the nearest vicinity of the triple line. This paper shows that not only apparent contact angle but also energy of adhesion are important for the correct characterization of the wetting situation. The energy of adhesion in turn is dictated by the total area of solid surface wetted by a droplet.



4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Experimental Composite surfaces were manufactured as follows. At the first stage superhydrophobic surfaces were prepared by the hot embossing of low density polyethylene (LDPE) films. LDPE films were fabricated by extrusion with a single screw extruder (RCP-0750). The thickness of the extruded films was of about 1 mm. The obtained films were exerted to hot embossing with the manually operated heated hydraulic Press P/N 15011/25011 under the pressure of about 10 MPa. The temperature of embossing was 105 °C. The hot embossing process is illustrated in Figure 1. Hot embossing was carried out with micro-scaled stainless steel wire gauzes used as stamps. Gauzes were supplied by A. D. Sinun (Israel). The SEM image of the gauze is presented in Figure 2. The gauzes have been glued to 10 cm×10 cm steel plates with the use of the heat-proof epoxy adhesive. The SEM images of reliefs produced by hot embossing are depicted in Figure 3A–B. SEM imaging was carried out with high resolution SEM (JSM-6510 LV). The “hairy” surfaces depicted in Figure 3A-B demonstrated pronounced superhydrophobicity; apparent contact angles as high as 150±3° and sliding angles as low as 10° for 10 µl water droplets were registered on these surfaces. The 4 µl water droplet deposited on the “hairy” superhydrophobic surface is depicted in Figure 4.


Page 4 of 20

Page 5 of 20


5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

heated dies of the press

moving die with gauze сетка

LDPE film embossed film

Figure 1. Scheme of the preparing of superhydrophobic surfaces by hot embossing process.

Figure 2. SEM image of the stainless steel wire gauzes used for hot embossing of polymer (LDPE) films. The scale bar is 200 µm.

The non-superhydrophobic spots were produced on the “hairy” surfaces shown in Figure 3A-B. The surfaces were carefully pressed with a metallic needle at ambient conditions, thus “hairy” structures shown in Figure 3A-B were destroyed and



6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

rough surface reliefs such as depicted in Figure 5A-B were produced. Spots with a characteristic size of 500 µm comprising destroyed “hairy” reliefs, shown in Figure 5A-B structures were produced. Large-area rough non-superhydrophobic surfaces with a relief, shown in Figure 5A-B were manufactured for the purpose of characterization of their wetting regime.

A

B


Page 6 of 20

Page 7 of 20


7 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 3. SEM images of hairy superhydrophobic LDPE reliefs produced with the hot embossing process utilizing metallic gauzes shown in Figure 2 as templates. A. Scale bar is 100 µm, B. Scale bar is 50 µm.

2-4 µl water droplets were carefully deposited with use of micro-syringe mounted on precise XYZ stage axisymmetrically on the superhydrophobic surfaces including non-superhydrophobic rough spots, as shown in Figure 6.

Figure 4. 4 µl water droplet deposited on hairy superhydrophobic surface depicted in Figure 3.

A

B



Page 8 of 20

8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 5. Rough surfaces obtained when a metallic needle was introduced into “hairy” reliefs depicted in Figure 3A-B. A. Scale bar is 100 µm. B. Scale bar is 50 µm.

liquid

superhydrophobic relief

non-superhydrophobic spot Figure 6. Scheme showing axisymmetric deposition of a droplet on a composite superhydrophobic surface comprising non-superhydrophobic spot.

Apparent contact angles were measured by Ramé-Hart Advanced Goniometer Model 500-F1. Advancing, receding and sliding angles were measured using a labmade supplement to the goniometer, allowing gradual tilting of the surface with a step of one degree.

Results and Discussion Hairy LDPE structures, manufactured as described in the Experimental Section and depicted in Figure 3A-B, demonstrated pronounced superhydrophobicity i.e. high apparent contact angles 150 ± 3° (shown in Figure 4) and low contact angle hysteresis, accompanied by low sliding angles (~10° for 10 µl droplets). The observed


Page 9 of 20


9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

superhydrophobicity of “hairy” LDPE surfaces is due to the pronounced CassieBaxter air trapping wetting regime resulting in the so-called “lotus effect”.15–24 Large area non-superhydrophobic rough surfaces depicted in Figure 5 demonstrated moderate hydrophobicity. i.e. apparent contact angles of 120 ± 5° and high contact angle hysteresis, illustrated with Figure 7. The 4 µl droplet remained attached to these surfaces, when they were tilted at arbitrary angle, and even when they were turned upside down, as also shown in Figure 7. The advancing contact angle established on these surfaces was 122 ± 5° , and the receding contact angle was 102 ± 5°.

Figure 7. 4 µl droplet deposited on the large area rough non-superhydrophobic surface. The droplet is attached to the surface even when the surface is turned upside down.

The most interesting wetting behavior was observed when a droplet was deposited axisymmetrically on the superhydrophobic surface comprising nonsuperhydrophobic central spot. In this case high apparent contact angles of 150 ± 3° were accompanied by the high contact angle hysteresis, as shown in Figuer 8. The 2 µl droplet remained adhered to the surfaces even when they turned upside down as depicted in Figure 8. Thus, we conclude that the composite surface containing non-



10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

superhydrophobic blemishes demonstrated manifestation of the so-called “rose petal effect”, reported first by Jiang et al. (Ref. 25) and exposed to intensive experimental and theoretical research recently.25–29 The heavier 10 µl droplet deposited on these surfaces (demonstrating high contact angle hysteresis) slides at the sliding angle of 20°. The advancing contact angle established on these surfaces was 165 ± 3° , and the receding contact angle was 129 ± 2°.

Figure 8. 2 µl droplet deposited on the superhydrophobic surface comprising nonsuperhydrophobic central blemish (see Scheme, presented in Figure 6).

High adhesion of droplets accompanied with high apparent contact angles could be explained easily in our case. Apparent contact angles are dictated by the superhydrophobic “hairy” area of the solid surface adjacent to the triple line, shown in Figure 3 (see Ref. 11). At the same time the energy of adhesion of a droplet is influenced by the entire area of the wetted solid. Consider for sake of simplicity a droplet with the radius of the contact area r deposited axysimmetrically on the flat composite surface, comprising a spot with the radius a, depicted in Figures 9–10A. It


Page 10 of 20

Page 11 of 20


11 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

is supposed that the difference r–a is much larger than the “width” of the triple line, i.e. r − a >> 5 µm takes place (see Ref. 13–14). Let the specific surface energies (interfacial tensions) of the solid/air and solid/liquid interfaces of the central spot be γ SA1 , γ SL1 and the specific surface energies of the solid/air and solid/liquid interfaces of the external circle be γ SA2 , γ SL 2 (see Figures 9-10). The energy of adhesion which is necessary for disconnection of the droplet could be calculated according to: Wad = GSA + G L − GSL ,

(1)

where GSA is the free surface energy of the “dry” solid/air interface, G L is the free surface energy of the liquid/air interface of the basal plane of the disconnected droplet (shown in Figure 10B), and GSL is the free surface energy of the solid/liquid interface in the situation, depicted in Figure 10A. Thus, the energy of adhesion of a droplet is given by:

Wad = γ SA1πa 2 + γ SA2π ( r 2 − a 2 ) + γπr 2 − γ SL1πa 2 − γ SL 2π ( r 2 − a 2 ) .

(2)

Involving the Young equations (the composite surface is supposed to be flat), i.e.: γ SA1 − γ SL1 = γ cos θ1 ; γ SA2 − γ SL 2 = γ cos θ 2 (where θ1 , θ 2 are the Young contact angles of central spot/liquid and surrounding circle/liquid pairs respectively) yields a more compact expression for the adhesion energy:

Wad = γπ ( r 2 + a 2 cosθ1 + ( r 2 − a 2 ) cosθ 2 ) .

(3)

~ For the specific energy of adhesion related to the unit area of solid W we have: a2 a2 ~ W W = ad2 = γπ (1 + 2 cos θ1 + (1 − 2 ) cos θ 2 ) . r r πr

(4)

It is recognized from Eqs. (3)–(4) that the adhesion energy of a droplet deposited on the flat chemically heterogeneous surface depends on the wetting



Page 12 of 20

12 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

properties of an entire area, wetted by a droplet. Physical and geometrical parameters characterizing both a central blemish and a surrounding circle appear explicitly in Eqs. (3)–(4).

ߛௌ஺ଵ a ߛௌ஺ଶ Figure 9. Flat chemically heterogeneous surface characterized by the specific surface energy γ SA 2 comprising round blemish, possessing specific surface energy γ SA1 (top view).

If a droplet is deposited on the rough composite surface (the central spot and surrounding circle possess roughness f1 and f2 respectively as depicted in Figure 11), Eqs. (3)–(4) could be easily generalized for the Wenzel wetting regime [30, 31]:

Wad = γπ ( r 2 + a 2 cosθ1* + ( r 2 − a 2 ) cosθ 2* ) ,

(5)

a2 a2 ~ W W = ad2 = γπ (1 + 2 cos θ1* + (1 − 2 ) cos θ 2* ) , πr r r

(6)

where θ1* ,θ 2* are the Wenzel apparent contact angles supplied by: cos θ1* = f 1 cos θ1 ; cos θ 2* = f 2 cos θ 2 (recall that the roughness f is defined as the ratio of the real surface in contact with liquid to its projection onto the horizontal plane). It is distinctly seen from Eqs. (5)–(6) that the energy of adhesion of droplet is influenced by a surface energy and roughness of both wetted central spot and a surrounding circle.


Page 13 of 20


13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The presented analysis supplies one of the possible qualitative explanations to the “rose petal effect”; indeed, high apparent contact angles do not necessarily provide an easy sliding of droplets. There exist various experimental situations, when “sticky” wetting is attended with high apparent contact angles.25–29,

32, 33

We report

one of such possibilities, when a superhydrophobic surface contains nonsuperhydrophobic blemish.

2r

γSL2

γSL1

γSL2

2r γSA1

γSA2

2a

2a

AAA

B

γSA2

Figure 10. A. Droplet with the radius of the contact area r deposited axisymmetrically on a flat composite surface, comprising a spot with the radius a (side view). Interfacial tensions γ SA1 , γ SA 2 , γ SL1 , γ SL 2 are depicted. B. Droplet disconnected from a composite surface.

droplet 2r 2a

f2

f1

f2



Page 14 of 20

14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 11. Scheme of a drop deposited axisymmetrically on a rough surface possessing roughness f2 and comprising the round spot of radius a possessing roughness f1.

The experimental situation discussed in Ref. 32, when high apparent contact angles were accompanied by high adhesion of a droplet is noteworthy. Liu et al. reported the reverse Wenzel-to-Cassie transitions observed for heated droplets deposited on superhydrophobic surfaces.32 In this case, the droplet demonstrated a high apparent contact angle, governed by the Cassie (vapor trapping) wetting in the vicinity of the triple line, and has been simultaneously sticky due to Wenzel water “bridges” connecting the droplet with the central area of the substrate underneath the droplet.33 Our derivation of the energy of adhesion is based on the traditional YoungDupre approach when the energy of droplet wetting the surface is compared to the energy of the liquid cap (see Figure 10). It is latently supposed that the shape of a droplet is not changed when it is disconnected from the surface. Shrader suggested that the droplet detached from the substrate obtains its natural spherical shape and supplied the corrected equation for the net energy of the droplet adhesion.34 When the “spherical drop” is taken as the reference state, the energy of adhesion for the situation, depicted in Figures 9, 10A will be given by:

Wad = Gsphericaldrop − Gsessiledrop ,

(7)

where Gsphericaldrop is the free energy of formation of the spherical drop from its saturated vapor, and Gsessiledrop is the free energy of formation of the sessile drop on a surface.34 The calculations according to Eq. (7) lead to somewhat cumbersome


Page 15 of 20


15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

expressions, however Gsessiledrop obviously depends on the physical and chemical composition of the solid surface, hence the general conclusion remains the same: the energy of adhesion depends on the entire surface wetted by a droplet, as it was already suggested by Tadmor et al.35-36 It is noteworthy that the process of hot embossing of polyethylene films with micro-scaled stainless steel gauzes reported in our paper allows manufacturing of not only superhydrophobic but also superoleophobic surfaces. Superoleophobicity is achieved, when hot embossing is followed by tetrafluoromethane plasma treatment.37

Conclusions Contact angles are important and easily measured macroscopic physical values describing the wetting of flat and rough, chemically homogeneous and heterogeneous solid surfaces. However, the complete macroscopic description of a wetting regime is achieved when not only the apparent contact angles but also the energy of adhesion are known. Apparent and Young contact angles are dictated by the area of a solid surface adjacent to the triple (three-phase) line, whereas the energy of adhesion depends on the surface energy and roughness of the entire area wetted by liquid. The paper discusses wetting of the superhydrophobic surface comprising a nonsuperhydrophobic blemish. A water droplet with the radius larger than this of a blemish, deposited on a blemish axisymmetrically, demonstrates the high apparent contact angle and remains in a “sticky” (high adhesion) wetting state. This observation can be explained easily with the use of the Dupre equation applied to the composite surface, showing explicitly that the energy of adhesion of a droplet is influenced by a surface energy and roughness of both the wetted central spot and the



16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

surrounding circle. The composite surface reported in the manuscript demonstrates a manifestation of the “rose petal effect”.

Acknowledgements The authors are grateful to Dr. G. Whyman for extremely fruitful discussions. The authors are thankful to Dr. R. Grynyov for his inestimable help in preparing superhydrophobic surfaces and SEM imaging. The authors are indebted to Mrs. Natalya Litvak for her help in SEM imaging.

References (1)

Gao, L.; McCarthy, T. J. How Wenzel and Cassie Were Wrong. Langmuir

2007, 23, 3762- 3765. (2)

Gao, L.; McCarthy, T. J. An Attempt to Correct the Faulty Intuition Perpetuated by the Wenzel and Cassie “Laws”. Langmuir 2009, 25, 72497255.

(3)

McHale, G. Cassie and Wenzel: Were They Really So Wrong? Langmuir

2007, 23, 8200- 8205. (4)

Panchagnula, M. V.; Vedantam, S. Comment on How Wenzel and Cassie Were Wrong by Gao and McCarthy. Langmuir 2007, 23, 13242 -13242.

(5)

Nosonovsky, M. On the Range of Applicability of the Wenzel and Cassie Equations. Langmuir 2007, 23, 9919- 9920.

(6)

Marmur, A.; Bittoun, E. When Wenzel and Cassie Are Right: Reconciling Local and Global Considerations. Langmuir 2009, 25, 1277- 1281.


Page 16 of 20

Page 17 of 20


17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(7)

Marmur, A. A Guide to the Equilibrium Contact Angles Maze. In Mittal, K. L. (Ed.) Contact Angle Wettability and Adhesion, V. 6, Brill/VSP, Leiden, 2009, pp. 3–18.

(8)

Milne, A. J. B.; Amirfazli, A. The Cassie Equation: How It Is Meant to Be Used. Adv. Colloid and Interface Sci. 2012, 170, 48-55.

(9)

Erbil, H. Y.; Cansoy, C. E.

Range of Applicability of the Wenzel and

Cassie−Baxter Equations for Superhydrophobic Surfaces. Langmuir 2009, 25, 14135- 14145. (10)

Kwon, Y.; Cho, S.; Anantharaju, N.; Lee, L. Panchagnula, M. V.; Patankar, N. A. Is the Cassie−Baxter Formula Relevant? Langmuir 2010, 26, 1752817531.

(11)

Bormashenko, E. A Variational Approach to Wetting of Composite Surfaces: Is Wetting of Composite Surfaces a One-Dimensional or Two-Dimensional Phenomenon? Langmuir 2009, 25, 10451-10454.

(12)

Bormashenko, E. Wetting Transitions on Biomimetic Surfaces. Phil. Trans. R. Soc. A 2010, 368, 4695-4711.

(13)

Leh, A.; N’guessan, H. E.; Fan, J.; Bahadur, Pr.; Tadmor, R.; Zhao, Y. On the Role of the Three-Phase Contact Line in Surface Deformation. Langmuir

2012, 28, 5795−5801. (14)

Bormashenko, E.; Bormashenko, Ye.; Stein, T.; Whyman, G.; Pogreb R. Environmental Scanning Electron Microscopy Study of the Fine Structure of the Triple Line and Cassie−Wenzel Wetting Transition for Sessile Drops Deposited on Rough Polymer Substrates. Langmuir 2007, 23, 4378–4382.

(15)

de Gennes, P. G.; Brochard-Wyart, F.; Quéré, D. Capillarity and Wetting Phenomena, Springer, Berlin, 2003.



18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(16)

Cassie, A. B. D.; Baxter, S. Wettablity of Porous Surfaces. Trans. Faraday Soc. 1944, 40, 546-551.

(17)

Cassie, A. B. D. Contact Angles. Discuss. Faraday Soc. 1948, 3, 11-16.

(18)

Barthlott, W.; Neinhuis, C. Purity of the Sacred Lotus, or Escape from Contamination in Biological Surfaces. Planta 1977, 202, 1-8.

(19)

Koch, K.; Barthlott, W. Superhydrophobic and Superhydrophilic Plant Surfaces: an Inspiration for Biomimetic Materials. Philos. Trans. R. Soc. London A 2009, 367, 1487-1509.

(20)

Yoshimitsu, Z.; Nakajima, A.; Watanabe, T.; Hashimoto, K. Effects of Surface Structure on the Hydrophobicity and Sliding Behavior of Water Droplets. Langmuir 2002, 18, 5818-5822.

(21)

Nosonovsky, M.; Bhushan, B. Roughness-Induced Superhydrophobicity: a Way to Design Non-Adhesive Surfaces. J. Phys.: Condens. Matter 2008, 20, 225009.

(22)

Nosonovsky, M.; Bhushan, B. Biologically Inspired Surfaces: Broadening the Scope of Roughness. Adv. Funct. Mater. 2008, 18, 843-855.

(23)

Kietzig, A.-M.; Hatzikiriakos, S. G.; Englezos, P. Patterned Superhydrophobic Metallic Surfaces. Langmuir 2009, 25, 4821-4827.

(24)

Fernández-Blázquez, J. P.; Fell, D.; Bonaccurso, E.; del Campo, A. J. Colloid & Interface Sci. Superhydrophilic and Superhydrophobic Nanostructured Surfaces via Plasma Treatment. 2011, 357, 234-238.

(25)

Feng, L.; Zhang, Y.; Xi, J.; Zhu, Y.; Wang, N.; Xia, F.; Jiang, L. Petal Effect: A Superhydrophobic State with High Adhesive Force. Langmuir 2008, 24, 4114-4119.


Page 18 of 20

Page 19 of 20


19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(26)

Bormashenko, E.; Stein, T.; Pogreb, R.; Aurbach, D. “Petal Effect” on Surfaces Based on Lycopodium: High-Stick Surfaces Demonstrating High Apparent Contact Angles. J. Phys. Chem. C 2009, 113, 5568-5572.

(27)

Park, Y. M.; Gang, M.; Seo, Y. H.; Kim, B. H. Artificial Petal Surface Based on Hierarchical Micro- and Nanostructures. Thin Solid Films 2011, 520, 362367.

(28)

Bhushan, B.; Nosonovsky, M. The Rose Petal Effect and the Modes of Superhydrophobicity. Phil. Trans. Royal Society A 2010, 368, 4713-4728.

(29)

Samuel, B.; Zhao, N.; Law, K-Y. Study of Wetting and Adhesion Interactions between Water and Various Polymer and Superhydrophobic Surfaces. J. Phys. Chemistry C 2011, 115, 14852-14861.

(30)

Wenzel, R. N. Resistance of Solid Surfaces to Wetting by Water. Ind. Eng. Chem. 1936, 28, 988-994.

(31)

Bormashenko, E.

Young, Boruvka–Neumann, Wenzel and Cassie–Baxter

Equations as the Transversality Conditions for the Variational Problem of Wetting. Colloids & Surfaces A 2009, 345, 163-165. (32)

Liu, G.; Fu, L.; Rode, A. V.; Craig, V. S. J. Water Droplet Motion Control on Superhydrophobic Surfaces: Exploiting the Wenzel-to-Cassie Transition. Langmuir 2011, 27, 2595-2600.

(33)

Bormashenko, E. Comment on

Water Droplet Motion Control on

Superhydrophobic Surfaces: Exploiting the Wenzel-to-Cassie Transition. Langmuir 2011, 27, 12769-12770. (34)

Schrader, M. Young-Dupre Revisited. Langmuir 1995, 11, 3585–3589.



20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(35)

Tadmor, R.; Bahadur, Pr.; Leh, A.; N’guessan, H. E.; Jaini, R.; Dang, L. Measurement of Lateral Adhesion Forces at the Interface between a Liquid Drop and a Substrate. Phys. Rev. Lett. 2009, 103, 266101.

(36)

Tadmor, R. Approaches in Wetting Phenomena. Soft Matter 2011, 7, 1577– 1580.

(37)

Bormashenko, E.; Grynyov, R.; Chaniel, G.; Taitelbaum, H.; Bormashenko, Y. Robust Technique Allowing Manufacturing Superoleophobic Surfaces. Applied Surface Sci. 2013, 270, 98–103.

TOC Image


Page 20 of 20

Wetting of Composite Surfaces - American Chemical Society

Recommend Documents