ARTICLE pubs.acs.org/Langmuir
Surface Structuration (Micro and/or Nano) Governed by the Fluorinated Tail Lengths toward Superoleophobic Surfaces Herve Bellanger, Thierry Darmanin, and Frederic Guittard* Laboratoire de Chimie des Materiaux Organiques et Metalliques, Equipe Chimie Organique aux Interfaces, Universite de Nice-Sophia Antipolis, Equipe chimie organique aux interfaces, 06108 Nice Cedex 2, France
bS Supporting Information ABSTRACT: As compared to superhydrophobic surfaces, the challenge to obtain superoleophobic properties, surfaces against low-surface-tension probe liquids such as hexadecane, is very important because of their high tendency to wet. From the molecular design of the monomer, it is possible to obtain in one step superoleophobic surfaces by electrodeposition. Hence, we report the synthesis and the characterization of an original series of fluorinated 3,4-ethylenedioxypyrrole (EDOP) derivatives. The electrodeposited polymer films are characterized by contact angle measurements (static and dynamic with various probe liquids), optical profilometry, and scanning electron microscopy. In the view toward reaching superoleophobic properties, a common approach is to increase the number of fluoromethylene units of the surface post-treatment agent. Here, surprisingly, it is possible, in one step, to reach more efficient antioil surface properties by decreasing the length of the fluorinated tail (F-octyl to F-hexyl). This fact can be explained by a double scale of structuration (micro and nano) induced using only F-hexyl tails.
’ INTRODUCTION The very high tendency of oils to spread, as induced by their low surface tension, leads to great difficulty in obtaining superoleophobic surfaces, also named super-oil-repellent surfaces.16 If two parameters (surface roughness and intrinsic hydrophobicity) are sufficient to reach superhydrophobic surface properties,79 then in most of the cases a third parameter should be added for superoleophobicity: surface morphology that is able to impede oil penetration. For example, in the case of surfaces made by lithography, superoleophobic surfaces were fabricated by changing the classical crenelated surface morphology by a reentrant one.36 However, such surfaces are difficult and expensive to produce and explain the small number of publications as compared to those dedicated to superhydrophobic properties.1012 Electrochemical methods have many advantages, including their cost, ease of manipulation, reproducibility, and process control with many parameters. Surfaces with adapted morphology can be produced using these methods. For instance, fractal surfaces with liquid-repellency properties were shown by the anodic oxidation of aluminum and silicon electrodes.1315 Other electrochemical processes include the deposition of metals and metal oxides such as gold,1618 silver,19 copper,20 and ZnO.21 Conducting polymers such as polypyrroles or polythiophenes can also be electrochemically deposited to form structured films.1,2,2225 The possible incorporation of a functional substituent leads to a very versatile method. In the case of the fabrication of antiwetting surfaces, the grafting of hydrocarbon or fluorocarbon tails onto the polymerizable moiety allowed us to obtain surfaces with various liquid-repellent properties. r 2011 American Chemical Society
Many parameters could be used to modify the surface wettability, such as the deposition charge, the salt, and the substrate,2 but one of the more promising parameters is the chemical structure of the monomer. 3,4-Ethylenedioxypyrrole (EDOP) is an exceptional platform in the development of electrodeposited films because of its extremely low oxidation potential combined with its high stability and the electrochromic properties of the polymer films.26,27 Previously, the wettabilities of electrodeposited films obtained from fluorinated EDOP and 3,4-propylenedioxypyrrole (ProDOP) derivatives containing the same fluorinated chain length and using the same electrochemical parameters were compared.1 The modification of the alkylenedioxy bridge by one methylene unit brought about a drastic change in the surface oleophobicity. This surface property was induced by the presence of surface nanoporosity observed only in fluorinated polyEDOP films. Here, the modification of the spacer between the 3,4-ethylenedioxypyrrole heterocycle and the oxy-carbonyl connector was modified in order to reach a gain in mobility of the fluorinated tail. We report the synthesis and characterization of original fluorinated EDOP derivatives (Scheme 1, EDOPC3Fn) following the chemical method represented in Scheme 2. The monomers were electrodeposited, and the surface properties, roughness, and antioil properties were analyzed. Received: September 1, 2011 Revised: November 28, 2011 Published: November 28, 2011 186
dx.doi.org/10.1021/la2034356 | Langmuir 2012, 28, 186–192
Langmuir
ARTICLE
’ EXPERIMENTAL SECTION
anhydrous dichloromethane. After the solution was stirred for 30 min at room temperature, EDOPC3OH (1.0 equiv) was added. After a day, the solvent was removed and the crude was purified by column chromatography (silica gel, dichloromethane eluent) to yield the products. The characterization of EDOPC3F8 is given below whereas those of EDOPC3F6 and EDOPC3F4 are given in the Supporting Information.
3,4-Ethylenedioxypyrrole (EDOP) was synthesized in eight steps from iminodiacetic acid.28 The chemical procedures to obtain 2-(tertbutyldimethylsilyloxy)propanol (M1) and 2-tert-butyldimethylsilyloxypropyltosylate (M2) are given in the Supporting Information.
Synthesis of 2-(2,3-Dihydro-[1,4]dioxino[2,3-c]pyrrol-6-yl)propanol (EDOPC3OH). To a solution of EDOP (170 mg, 1.37 mmol) in anhydrous THF was added dry sodium hydride (40 mg, 1.64 mmol). After being stirred for 30 mn, 2-tert-butyldimethylsilyloxypropyltosylate (561 mg, 1.64 mmol) was added and the reaction mixture was refluxed for 24 h. After the solution was cooled and the solvent was evaporated, aqueous ammonium chloride was carefully added and the solution was extracted with diethyl ether and dried over Na2SO4. The removal of the solvent and purification by column chromatography (silica gel, dichloromethane eluent) gave a mixture of the product protected by a silyl group (at rt, 15.6 mn) and 2-tert-butyldimethylsilyloxypropyl tosylate. To this mixture was added tetrabutylammonium fluoride in THF to release the hydroxyl group. After the solution was stirred for 24 h at 60 °C and the solvent was evaporated, purification by column chromatography (silica gel, dichloromethane eluent) afforded the product as a colorless liquid at rt, 11.8 min. 1H NMR (200 MHz, CDCl3, δH): 6.08 (s, 2H), 4.18 (s, 4H), 3.82 (t, 3JHH = 6.7 Hz, 2H), 3.61 (m, 3H), 1.91 (quint, 3JHH = 6.1 Hz, 2H). Synthesis of EDOPC3Fn. DMAP (30 mg) and N-(3-(dimethylaminopropyl)-N0 -ethylcarbodiimide hydrochloride (EDC) (1.2 equiv) were added to a solution of the corresponding semifluorinated acid (1.2 equiv) in
EDOPC3F8: 3-(2H-[1,4]Dioxino[2,3-c]pyrrol-6(3H)-yl)propyl 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-heptadecafluoroundecanoate. Yield 29% at rt, 17.5 min; white powder; mp 4748 °C.
H NMR (200 MHz, CDCl3, δH): 6.05 (s, 2H), 4.17 (s, 2H), 4.08 (t, 3JHH = 6.2 Hz, 2H), 3.76 (t, 3JHH = 6.7 Hz, 2H), 2.64 (t, 3JHH = 7.0 Hz, 2H), 2.47 (tt, 3JHH = 7.0 Hz, 3JHF = 18.7 Hz, 2H), 2.02 (quint, 3JHH = 6.4 Hz, 2H). 13C NMR (50 MHz, CDCl3, δC): 170.96, 132.11, 101.08, 65.79, 62.19, 46.67, 30.25, 26.48 (t, 2JCF = 21.8 Hz), 25.41 (t, 3JCF = 3.8 Hz). MS (70 eV): m/z (%): 657 (34) [M+], 475 (8) [C11H4OF17+•], 182 (35) [C9H12NO3+], 139 (100) [C7H9NO2+•]. FTIR (main vibrations): ν = 2925, 2857, 1730, 1203, 1149 cm1. 1
’ RESULTS AND DISCUSSION Electrochemical Polymerization. The electropolymerization experiments were performed by adding 0.1 M tetrabutylammonium hexafluorophosphate and 10 mM monomer to anhydrous acetonitrile. The monomer oxidation potentials, determined by cyclic voltammetry, were 0.93 V versus SCE for EDOPC3F4 and EDOPC3F8 and 0.90 V for EDOPC3F6. Then, 10 scans were performed until a potential slightly lower that the monomer oxidation potential was reached in order to confirm the polymerizability of each monomer and to identify the polymer redox systems. The cyclic voltammograms for the three monomers are given in Figure 1. Previously, we demonstrated1a that the presence of a peak at about 0.40.5 V versus SCE in the voltammograms of EDOP derivatives (bipolaronic forms) may be responsible for the nanoporosity formation
Scheme 1. Studied Monomers: EDOPC3Fn (n = 4, 6, 8)
Scheme 2. Synthesis Route to the EDOPC3Fn Monomers
187
dx.doi.org/10.1021/la2034356 |Langmuir 2012, 28, 186–192
Langmuir
ARTICLE
Figure 1. Cyclic voltammograms of the EDOPC3Fn series (0.01 M) recorded on a Pt electrode and in 0.1 M Bu4NPF6/CH3CN.
Figure 3. Static contact angles of hexadecane as a function of the deposition charge.
Figure 2. Infrared spectra of polyEDOPC3F6 obtained by infrared imaging.
and, as a consequence, the superoleophobic properties. Here, for EDOPC3F8 and EDOPC3F6, a decrease in this peak was observed as the alkyl spacer (ethyl1 to propyl). For EDOPC3F4, the doping process was not the same during the polymer growth: a large increase in the first peak (0.21 V during the forward scan) during the first scans and then the intensity of this peak decreased and the second peak increased (0.38 V during the forward scan). Indeed, the mobility of F-butyl chains is much more important than that of F-octyl chains as observed by Takahara et al. by comparing the molecular aggregation states and surface properties of poly(fluoroalkyl acrylate) with various fluorinated chain lengths.29 The higher mobility of F-butyl may reduce the π stacking of the polymer chains and modify the intra- and intermolecular interactions and, as a consequence, the doping process. Electrodeposited Film Characterization. For surface analyses, polymer films were electrodeposited on large gold plates by an imposed potential using various deposition charges (Qs). The arithmetic roughness (Ra) and rms roughness (Rq) were measured using a WYKO NT1100 optical profilometer on an area of 182 239 μm2. The surface morphology was investigated by scanning electron microscopy (SEM) using a JEOL 6700F. The surface wettability was characterized by static contact angle measurements (CAx, where x is the probe liquid) with 2 μL droplets and dynamic contact angle measurements (sliding angle, αx, and hysteresis, Hx) with 6 μL droplets using the tilted-drop method. The polymer was characterized by infrared spectroscopy using a spectrum spotlight 300. The presence of the polymer was confirmed by the ester band at 1735 cm1 and the broad band centered at 1193 cm1 attributed to CF bonds from the fluorinated chains. Example spectra are given in Figure 2. Liquid-Repellency Properties. The antiliquid properties were evaluated with various probe liquids. First, the superhydrophobic properties were measured with water droplets (γL = 72.8 mN/m). PolyEDOPC3F6 showed the best antiwetting properties. Indeed,
if the three polymers were superhydrophobic, with static contact angles of water higher than 157°, then the lower hysteresis and sliding angle values were measured with polyEDOPC3F6 (Hw = 20.9° and αw = 12.0° for polyEDOPC3F4; Hw = 2.0° and αw = 1.1° for polyEDOPC3F6; and Hw = 11.0° and αw = 5.5° for polyEDOPC3F8). Then, to determine the superoleophobic properties, hexadecane (γL = 27.6 mN/m) was used as standard probe liquid. Figure 3 shows the influence of the contact angles of hexadecane as a function of the deposition charge for each polymer. The best values were measured with hexadecane for Qs = 400 mC/cm2 (CAh = 131.4° for polyEDOPC3F4, CAh = 150.0° for polyEDOPC3F6, and CAh = 145.2° for polyEDOPC3F8). Dynamic contact angle measurements revealed that hexadecane droplets can roll off the surface only for polyEDOPC3F6 and that the hysteresis and sliding angle were minimal for Qs = 400 mC/cm2 (CAh,advancing = 152.2 °, CAh,receding = 130.3°, Hh = 21.9°, and αh = 11.1°). Thus, the super-oil-repellent properties of polyEDOPC3F6 films were more efficient than those of the previously reported films.1 This is also the first time that a decrease in the surface wettability was observed as the increase in the number of perfluorinated chains. To evaluate the influence of the surface tension of the probe liquid on the superoleophobic properties, apolar probe liquids with various surface tension values were chosen: diiodomethane (γL = 50.8 mN/m), dodecane (γL = 25.4 mN/m), decane (γL = 23.8 mN/m), octane (γL = 21.6 mN/m), and hexane (γL = 18.4 mN/m). The influence of the liquid surface tension on the oleophobic properties is schematized in Figure 4 (Qs = 225 mC/cm2). Two regimes could be clearly identified. The contact angle decreased dramatically for liquids with surface tension values lower than that of hexadecane. For hexadecane, polyEDOPC3F6 becomes more oleophobic than polyEDOPC3F8, which was unexpected. However, the ability to repel liquids of surface 188
dx.doi.org/10.1021/la2034356 |Langmuir 2012, 28, 186–192
Langmuir
ARTICLE
from the Wenzel to the CassieBaxter state by the plot of cos(θapparent) versus cos(θYoung) because of the impossibility of measuring the CA on a flat surface. Finally, polar probe liquids of different surface tensions were also chosen to evaluate the ability of these films to repel all types of liquids: DMF (γL = 37.1 mN/m) and ethanol (γL = 22.1 mN/m). The contact angles of these two polar liquids were lower than 90° even if the surface tension of DMF is much higher than that of hexadecane, showing the importance of the polar and apolar parts of the liquid surface tension on the liquid-repellent properties. Hence, the liquid-repellent ability of these surfaces is higher for apolar liquids than for polar ones. To understand the effect of the fluorinated chain on the superoleophobic properties, the surface morphology was investigated by scanning electron microscopy and optical profilometry.
tension lower than that of hexadecane is better with polyEDOPC3F8. We can thus assume that the surface geometry is predominant here in the wetting properties and that a metastable Cassie Baxter state is possible.30,31 For liquids of surface tension lower than that of hexadecane, the surface structuration is not sufficient to create a large airliquid interface. Thus, the liquid may be in a Wenzel state and the surface chemistry becomes predominant, which explains the increase in the contact angle with the fluorinated chain length.32 Unfortunately, we cannot confirm the transition
Table 1. Roughness Data in Nanometers as a Function of Qs Obtained by Optical Profilometry polyEDOPC3F8
polyEDOPC3F6
polyEDOPC3F4
Qs (mC/cm )
Ra
Rq
Ra
Rq
Ra
Rq
50 100
76 281
139 431
114 353
200 587
132 442
222 635
2
Figure 4. Static contact angles as a function of the surface tension of apolar probe liquids on polyEDOPC3Fn for n = 4 (square), n = 6 (crosses), and n = 8 (triangles) with Qs = 225 mC/cm2.
225
590
907
1652
2869
1726
2951
400
1819
2721
2928
4428
4655
5388
Figure 5. SEM images of the three polymers at two different magnifications ( 250 and 2000) and in cross section. Qs ≈ 225 mC/cm2. 189
dx.doi.org/10.1021/la2034356 |Langmuir 2012, 28, 186–192
Langmuir
ARTICLE
Figure 6. (a) Plot of intensity vs time during the potentiostatic deposition of polyEDOPC3F4, polyEDOPC3F6, and polyEDOPC3F8 and (b) the normalized plot.
Surface Roughness and Morphology. SEM images are given in Figure 5, and the roughness parameters are given in Table 1. First, as shown in Figure 5a,d,g, the microstructuration of the films increased as the fluorinated chain length decreased. This very important observation was confirmed by surface roughness analyses (Table 1). However, by increasing the magnification, the surface nanoporosity seemed to decrease as the fluorinated chain length decreased (Figure 5b,e,h). We can see in cross-sectional SEM images (Figure 5c,f,i) that the nanoporosity is limited at the extreme surface and the microstructures are filled. It also seems that depositions of polyEDOPC3F8 and polyEDOPC3F6 are more compact than that of polyEDOPC3F4, which looks like branching growth. These differences in compacity can explain the differences in surface wettability observed between polyEDOPC3F4 and the two others. Surface nanoporosity had already been observed in the previously reported films.1 Thus, polyEDOPC3F4 was microstructured and polyEDOPC3F8 was nanoporous. If in previous publications the second peak (0.40.5 V vs SCE) observed in the voltammogram could be attributed to the presence of surface nanoporosity in the electrodeposited films,1 here the second peak (∼0.40 V vs SCE) observed in the voltammogram of EDOPC3F4 (Figure 1) does not seem to be the sign of surface nanoporosity. By contrast, polyEDOPC3F6 was both microstructured and nanoporous. This peculiar double surface structuration imparted to polyEDOPC3F6 films the best antiwetting properties with hexadecane. Indeed, the nanoporosity observed here can be assimilated to the nanoscale re-entrant structure with rounded edges identified on superoleophobic surfaces recently produced because the porosity is formed here by cylindrical fibrils. This type of structure has been determined to be a necessary condition for superoleophobic surfaces.33 However, the microstructure, another important morphological characteristic, has to be considered here. Indeed, nanoporosity was observed for deposition charges of 225 and 400 mC/cm2, but a very high sliding angle with hexadecane was observed with the first one, suggesting a Wenzel predominant state, and a low sliding angle and hysteresis were observed with the second one, suggesting a predominant CassieBaxter state. We can thus assume here that the microstructure reached at 400 mC/cm2 plays an important role in dynamic CA and seems to be ideal here, in terms of geometrical parameters, to repel hexadecane. This assumption is supported by the work of Extrand, where critical values of spacing and dimensions of micropillars were
identified to switch the water behavior from a collapsed (Wenzel) state to a suspended (CassieBaxter) state on superhydrophobic surfaces.34 The pinning effect due to the shape of the top of the microstructure may also be involved here in the variation of hysteresis.35 However, it is somewhat difficult here to identify the nano- and microstructure portions involved in wetting properties because of the random character of these structures and the impossibility of measuring the contact angle on a flat surface. This work also confirms previous conclusions on the importance of the microstructuration on the superoleophobic properties.1b
’ DISCUSSION To understand the effect of the fluorinated cain length on the surface micro- and nanostructuration, it was absolutely necessary to separate its effect on the surface nanostructuration from its effect on the surface microstructuration. The mechanism that underlies the impact of the fluorinated chain length on the surface nanostructuration was previously demonstrated.1a We showed that the increase in the 3,4-alkylenedioxy bridge by one methylene unit could lead to drastic changes in the surface morphology (the presence or absence of nanoporosities) and, as a consequence, in the superoleophobic properties. We demonstrated by cyclic voltammetry that these differences were due to a complex doping process in the case of the nanoporous surfaces. Indeed, the increase in the 3,4-alkylenedioxy bridge induces higher mobility inside the polymer, which leads to a distortion of the polymer backbone and as a consequence limits the π-stacking interactions necessary for the intra- and intermolecular electronic exchanges. Here, it is known that the mobility of F-butyl chains is much higher than that of F-octyl chains because of the presence of interactions between long fluorinated tails.29 Hence, the fluorinated chain length decrease can have the same effect as the 3,4-alkylenedioxy bridge increase, which explains the presence of nanoporosities only in the polymer films containing F-octyl and F-hexyl chains. The influence of fluorinated chains on the surface microstructuration seems to be something more general in the electrodeposited conducting polymers. In the domain of electrodeposited conducting polymers, it is known that the surface morphology can be controlled by changing various electrochemical conditions.2,36 Recently, the group of Bendikov37 studied the effect of the solvent and the supporting electrolyte on the surface morphology of electrodeposited EDOT (nonsubstituted). They demonstrated that 190
dx.doi.org/10.1021/la2034356 |Langmuir 2012, 28, 186–192
Langmuir the major differences in surface morphology (structured or nonstructured surfaces) can be explained by differences in the oligomers electroformed during initial electropolymerization stages. More precisely, they underlined that the surface structuration increases as the oligomer insolubility increases. In the case of fluorinated conducting polymers, the presence of the fluorinated substituent may increase the polymer insolubility, and its presence can also lead to various surface morphologies by self-assembly between the fluorinated substituents.1,2,22,25 The literature shows that the fluorinated chain length may, in certain cases, decrease the size of the electrodeposited structures, as observed here. For example, the possibility to electrodeposit fluorinated 3,4-ethyleneoxythiathiophene polymer fibers with control over their dimensions by changing the fluorinated chain length (from micrometric with F-butyl chains to nanometric with F-octyl chains) has been previously demonstrated.22a To explain the influence of the fluorinated chain length effect on the surface microstructuration, we assume that the fluorinated chain length increase makes the polymer more insoluble (the more insoluble the polymer, the more quickly it is electrodeposited) and strengthens its self-assembly properties. Hence, with F-octyl chains, the polymer particles electroformed in the first instance probably do not have the time to grow to form 3D structures because of their electrodeposition speed. Furthermore, the plot of I versus t during electropolymerization in Figure 6a shows that the increase in intensity responsible of the first nuclei occurred after more than 10 s for polyEDOPC3F8, indicating that the nucleation and growth mechanism (NGM) is very different from polyEDOPC3F6 and polyEDOPC3F4 NGMs.38 Furthermore, these curves were correlated to theoretical curves of nucleation and growth used in the literature (Figure 6b). It was found that the NGM of polyEDOPC3F6 agreed well with the theoretical 3D instantaneous model during the first seconds, confirming the ability of EDOPC3F6 to form large 3D structures. NGM of polyEDOPC3F4 is meanwhile probably a combination of 2D and 3D contributions. 39
ARTICLE
’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ ACKNOWLEDGMENT T.D. and H.B. thank Jean-Pierre Laugier of the Centre Commun de Microscopie Appliquee (CCMA, University of Nice Sophia Antipolis) for the SEM images. ’ REFERENCES (1) (a) Darmanin, T.; Guittard, F. J. Am. Chem. Soc. 2009, 131, 7928–7933. (b) Darmanin, T.; Guittard, F.; Amigoni, S.; Taffin de Givenchy, E.; Noblin, X.; Kofman, R.; Celestini, F. Soft Matter 2011, 7, 1053–1057. (2) Darmanin, T.; Guittard, F. J. Mater. Chem. 2009, 19, 7130–7136. (3) Tuteja, A.; Choi, W.; Ma, M.; Mabry, J. M.; Mazzella, S. A.; Rutledge, G. C.; McKinley, G. H.; Cohen, R. E. Science 2007, 318, 1618–1622. (4) Joly, L.; Biben, T. Soft Matter 2009, 5, 2549–2557. (5) Marmur, A. Langmuir 2008, 24, 7573–7579. (6) Ahuja, A.; Taylor, J. A.; Lifton, V.; Sidorenko, A. A.; Salamon, T. R.; Lobaton, E. J.; Kolodner, P.; Krupenkin, T. N. Langmuir 2008, 24, 9–14. (7) Li, X.-M.; Reinhoudt, D.; Crego-Calama, M. Chem. Soc. Rev. 2007, 36, 1350–1368. (8) Taffin de Givenchy, E.; Amigoni, S.; Martin, C.; Andrada, G.; Caillier, L.; Geribaldi, S.; Guittard, F. Langmuir 2009, 25, 6448–6453. (9) Amigoni, S.; Taffin de Givenchy, E.; Dufay, M.; Guittard, F. Langmuir 2009, 25, 11073–11077. (10) (a) Liu, K.; Jiang, L. Nanoscale 2011, 3, 825–838. (b) Liu, K.; Yao, X.; Jiang, L. Chem. Soc. Rev. 2010, 39, 3240–3255. (c) Liu, M.; Jiang, L. Adv. Funct. Mater. 2010, 20, 3753–3764. (11) (a) Shirtcliffe, N. J.; McHale, G.; Newton, M. I. J. Polym. Sci., Part B: Polym. Phys. 2011, 49, 1203–1217. (b) Crick, C. R.; Parkin, I. P. Chem.—Eur. J. 2010, 16, 3568–3588. (12) (a) Liu, M.; Zheng, Y.; Zhai, J.; Jiang, L. Acc. Chem. Res. 2010, 43, 368–377. (b) Guo, Z.; Liu, W.; Su, B.-L. J. Colloid Interface Sci. 2011, 353, 335–355. (13) (a) Tsujii, K.; Yamamoto, T.; Onda, T.; Shibuichi, S. Angew. Chem., Int. Ed. 1997, 36, 1011–1012. (b) Shibuichi, S.; Yamamoto, T.; Onda, T.; Tsujii, K. J. Colloid Interface Sci. 1998, 208, 287–294. (14) Wang, M.-F.; Raghunathan, N.; Ziaie, B. Langmuir 2007, 23, 2300–2303. (15) Gu, C.; Zhang, T.-Y. Langmuir 2008, 24, 12010–12016. (16) Zhang, X.; Shi, F.; Yu, X.; Liu, H.; Fu, Y.; Wang, Z.; Jiang, L.; Li, X. J. Am. Chem. Soc. 2004, 126, 3064–3065. (17) (a) Jiang, Y.; Wang, Z.; Yu, X.; Shi, F.; Xu, H.; Zhang, X.; Smet, M.; Dehaen, W. Langmuir 2005, 21, 1986–1990. (b) Yu, X.; Wang, Z.; Jiang, Y.; Zhang, X. Langmuir 2006, 22, 4483–4486. (18) Li, Y.; Shi, G. J. Phys. Chem. B 2005, 109, 23787–23793. (19) Zhao, N.; Shi, F.; Wang, Z.; Zhang, X. Langmuir 2005, 21, 4713–4716. (20) Wang, S.; Feng, L.; Liu, H.; Sun, T.; Zhang, X.; Jiang, L.; Zhu, D. ChemPhysChem 2005, 6, 1475–1478. (21) Li, M.; Zhai, J.; Liu, H.; Song, Y.; Jiang, L.; Zho, D. J. Phys. Chem. B 2003, 107, 9954–9957. (22) (a) Darmanin, T.; Guittard, F. J. Am. Chem. Soc. 2011, 133, 15627–15634. (b) Darmanin, T.; Taffin de Givenchy, E.; Amigoni, S.; Guittard, F. Langmuir 2010, 26, 17596–17602. (23) (a) Darmanin, T.; Taffin de Givenchy, E.; Guittard, F. Macromolecules 2010, 43, 9365–9370. (b) Darmanin, T.; Guittard, F. Langmuir 2009, 25, 5463–5466. (24) Zenerino, A.; Darmanin, T.; Taffin de Givenchy, E.; Amigoni, S.; Guittard, F. Langmuir 2010, 26, 13545–13549.
’ CONCLUSIONS Here, we have synthesized an original series of fluorinated EDOP derivatives as monomers for the elaboration of superoleophobic surfaces by electrochemical polymerization. We pointed out that the introduction of one methylene unit into the alkyl spacer between the EDOP heterocycle and the fluorinated chain can significantly influence the wettability properties and turn on/off micro- to nanostructuration according to the lengthening of fluorinated tails. Surprisingly, the double scale (micro/nano) of structuration was obtained for F-hexyl tails between two limiting states (F-butyl w micro and F-octyl w nano) and is favorable to superoleophobic surface properties. Furthermore, the decrease in the number of fluorinated tail (F-octyl to F-hexyl) is favorable to obtaining less toxic materials because of the bioaccumulation of F-octyl tails described in PFOA and PFOS derivatives.4043 This work highlights that the decrease in the number of F-alkyl tails is possible to achieve efficient surfaces and opens new synthesis routes to bioinspired antiwetting materials with a favorable ecotoxic approach. ’ ASSOCIATED CONTENT
bS
Supporting Information. Monomer mass spectra. This material is available free of charge via the Internet at http://pubs. acs.org. 191
dx.doi.org/10.1021/la2034356 |Langmuir 2012, 28, 186–192
Langmuir
ARTICLE
(25) (a) Yan, H.; Kurogi, K.; Mayama, H.; Tsujii, K. Angew. Chem., Int. Ed. 2005, 44, 3453–3456. (b) Kurogi, K.; Yan, H.; Mayama, H.; Tsujii, K. J. Colloid Interface Sci. 2007, 312, 156–163. (c) Yan, H.; Kurogi, K.; Tsujii, K. Colloids Surf., A 2007, 292, 27–31. (26) (a) Beaujuge, P. M.; Reynolds, J. R. Chem. Rev. 2010, 110, 268–320. (b) Walczak, R. M.; Reynolds, J. R. Adv. Mater. 2006, 18, 1121–1131. (c) Thomas, C. A.; Zong, K.; Schottland, P.; Reynolds, J. R. Adv. Mater. 2000, 12, 222–225. (27) (a) Walczak, R. M.; Jung, J.-H.; Cowart, J. S., Jr.; Reynolds, J. R. Macromolecules 2007, 40, 7777–7785. (b) Gaupp, C. L.; Zong, K.; Schottland, P.; Thompson, B. C.; Thomas, C. A.; Reynolds, J. R. Macromolecules 2000, 33, 1132–1133. (28) Merz, A.; Schropp, R.; D€otterl, E. Synthesis 1995, 7, 795–800. (29) Honda, K.; Morita, M.; Otsuka, H.; Takahara, A. Macromolecules 2005, 38, 5699–5705. (30) Cassie, A. B. D.; Baxter, S. Trans. Faraday Soc. 1944, 40, 546–551. (31) Wolfs, M.; Darmanin, T.; Guittard, F. Macromolecules 2011, 44, 92869294 (32) Wenzel, R. N. Ind. Eng. Chem. 1936, 28, 988–994. (33) Joly, L.; Biben, T. Soft Matter. 2009, 5, 2549–2557. (34) Extrand, C. W. Langmuir 2004, 20, 5013–5018. (35) Kurogi, K.; Yan, H.; Tsujii, K. Colloids Surf., A 2008, 317, 592–597. (36) (a) Silk, T.; Hong, Q.; Tamm, J.; Compton, R. G. Synth. Met. 1998, 93, 59–64. (b) Mammone, R. J.; Binder, M. J. Electrochem. Soc. 1990, 137, 2135–2139. (c) Wood, G. A.; Iroh, J. O. Polym. Eng. Sci. 1996, 36, 2389–2395. (37) Poverenov, E.; Li, M.; Bitler, A.; Bendikov, M. Chem. Mater. 2010, 22, 4019–4025. (38) (a) Soto, J. P.; Diaz, F. R.; del Valle, M. A.; Velez, J. H.; East, G. A. Appl. Surf. Sci. 2008, 254, 3489–3496. (b) Hwang, B.-J.; Santhanam, R.; Lin, Y.-L. Electroanalysis 2003, 15, 115–120. (39) Wang, Y.; Northwood, D. O. M. Thin Solid Films 2008, 516, 7427–7432. (40) Conder, J. M.; Hoke, R. A.; de Wolf, W.; Russell, M. H.; Buck, R. C. Environ. Sci. Technol. 2008, 42, 995–1003. (41) Houde, M.; Martin, J. W.; Letcher, R. J.; Solomon, K. R.; Muir, D. C. G. Environ. Sci. Technol. 2006, 40, 3463–3473. (42) Giesy, J. P.; Kannan, K. Environ. Sci. Technol. 2001, 35, 1339–1342. (43) Kudo, N.; Kawashima, Y. J. Toxicol. Sci. 2003, 28, 49–57.
192
dx.doi.org/10.1021/la2034356 |Langmuir 2012, 28, 186–192
