From Hydrophilicity to Hydrophobicity: A Critical Review: Part I. Wettability and Surface Behavior


  • Cheng Piao
  • Jerrold E. Winandy
  • Todd F. Shupe


Hydrophobicity, hydrophilicity, wettability, surface tension, surface topography, contact angle, surface ageing, surface contamination


Surface properties of wood are important for both wettability and hydrophobic modification. Glueability of wood is related to wettability, while durability and decay resistance are affected by physical and chemical components. This review (Part I) discusses hydrophilic characteristics of surfaces. Surface theories, calculation methods for surface tension, topography, contamination, and aging are reviewed. It was found that surface tension data were often disparate; a standardized procedure for contact angle measurement would permit reproducible measurements and comparable data for surface characterization. Surface tension of wood can be estimated using Zisman's critical surface tension, geometric-mean, harmonic-mean, and acid-base approaches. To date, however, no procedures have been developed for determining absolute values of surface tension. Few controversies exist in the literature regarding effects of surface topographic characteristics on surface tension. However, there are disputes regarding mechanisms of surface contamination and aging. Further research on surface tension of wood is warranted. Hydrophobic modifications and superhydrophobic wood are discussed in Part II.


Adam NK (1949) The physics and chemistry of surfaces. 3rd ed. Oxford Univ. Press, London, UK. 436 pp.nAjuong EMA, Breese MC (1997) The role of extractives on short-term creep in compression parallel to the grain of Pai wood (Afzella Africana Smith). Wood Fiber Sci 29 (2):161-170.nArshadi M, Gref R (2005) Emission of volatile organic compounds from softwood pellets during storage. Forest Prod J 55(12):132-135.nBanks WB (1973) Water uptake by Scots pine sapwood, and its restriction by the use of water repellents. Wood Sci Technol 7:271-284.nBlanchard V, Blanchet P, Riedl B (2009) Surface energy modification by radiofrequency inductive and capacitive plasmas at low pressures on sugar maple: An exploratory study. Wood Fiber Sci 41(3):245-254.nBodig J (1962) Wettability related to gluabilities of fiber Philippine mahoganies. Forest Prod J 12(6):265-270.nBodig J, Jayne BA (1993) Mechanics of wood and wood composites. Krieger Publishing Company, Malabar, FL. 712 pp.nBuckton G (1995) Interfacial phenomena in drug delivery and targeting (Drug Targeting & Delivery Series). Harwood Academic Publishers, Chur, Switzerland. 304 pp.nButt HJ, Golovko DS, Bonaccurso E (2007) On the derivation of Young's equation for sessile drops: Nonequilibrium effects due to evaporation. J Phys Chem B 111:5277-5283.nCassie ABD (1948) Contact angles. Discuss Faraday Soc 3:11-15.nCassie ABD, Baxter S (1944) Wettability of porous surfaces. Trans Faraday Soc 40:546-551.nChen MJ (1970) Effect of extractive removal on adhesion and wettability of some tropical woods. Forest Prod J 20:36-41.nChen MJ (1972) Measuring the wetting of wood surfaces by adhesives. Mokuzai Gakkaishi 18(9):451-456.nChristiansen AW (1990) How overdrying wood reduces its bonding to phenol-formaldehyde adhesives: A critical review of the literature. Part I. Physical responses. Wood Fiber Sci 22(4):441-459.nChristiansen AW (1991) How overdrying wood reduces its bonding to phenol-formaldehyde adhesives: A critical review of the literature. Part II. Chemical reactions. Wood Fiber Sci 23(1):69-84.nDe Meijer M (2004) A review of interfacial aspects in wood coatings: Wetting, surface energy, substrate penetration and adhesion. Workshop Proceedings, High Performance Wood Coatings Symposium on Measurement Methods at Coating Consultancy, Copenhagen, February 16-17, 2004, Paris, France. 16 pp.nDe Moura LF, Hernández RE (2005) Evaluation of varnish coating performance for two surfacing methods on sugar maple wood. Wood Fiber Sci 37(2):355-366.nDougal EF, Wellons JD, Krahmer RL, Kanarek P (1980) Glueline characteristics and bond durability of Southeast Asian species after solvent extraction and planning of veneers. Forest Prod J 30(7):48-53.nDupre A (1869) Theorie mecanique de la Chaleur. Gauthier-Villars, Paris, France. 484 pp.nErbil HY (2006) Surface chemistry of solid and liquid interfaces. Blackwell Publ Ltd., Oxford, UK. 352 pp.nFeist WC, Mraz EA (1978) Wood finishing: Water repellents and water-repellent preservatives. Res. Note FPL-0124. USDA For Serv, Forest Products Laboratory, Madison, WI.nFowkes FM (1964) Attractive forces at interfaces. Ind Eng Chem 56(12):40-52.nFowkes FM (1972) Donor-acceptor interactions at inter-faces. J Adhesion 4:155-159.nFPL (1999) Wood handbook—Wood as an engineering material. Gen Tech Rep FPL-GTR. USDA For Serv Forest Products Laboratory, Madison, WI. 463 pp.nFreeman HA (1959) Properties of wood and adhesion. Forest Prod J 9(12):451-458.nFreeman HA, Wangaard FF (1960) Effect of wettability of wood on glue-line behavior of two urea resins. Forest Prod J 10(6):311-315.nGardner DJ (1996) Application of the Lifshtz-van der Waals acid-base approach to determine wood surface tension components. Wood Fiber Sci 28(4):422-428.nGardner DJ, Generalla NC, Gunnells DW, Wolcott MP (1991) Dynamic wettability of wood. Langmuir 7:2498-2502.nGindl M, Reiterer A, Sinn G, Stanzel-Tschegg SE (2004) Effects of surface ageing on wettability, surface chemistry, and adhesion of wood. Holz Roh Werkst 62:273-280.nGindl M, Sinn G, Gindl W, Reiterer A, Tschegg S (2001) A comparison of different methods to calculate the surface free energy of wood using contact angle measurements. Colloid Surface A 181:279-287.nGirifalco LA, Good RJ (1957) A theory for the estimation of surface and interfacial energies. I. Derivation and application to interfacial tension. J Phys Chem 61(7):904-909.nGood RJ (1979) Contact angles and the surface free energy of solids. Page 1 in RJ Good and RR Stromberg eds. Surface and Colloid Science. Vol VII. Plenum Press, New York.nGray VR (1962) The wettability of wood. Forest Prod J 12(9):452-461.nHalligan AF (1969) A review: Recent glues and gluing research applied to particleboard. Forest Prod J 19(1):44-51.nHerczeg A (1965) Wettability of wood. Forest Prod J 15(11):499-505.nHernández RE (2007) Moisture sorption properties of hardwoods as affected by their extraneous substances, wood density, and interlocked grain. Wood Fiber Sci 39(1):132-145.nHillis WE (1971) Distribution, properties and formation of some wood extractives. Wood Sci Technol 5:272-289.nHolmbom B (1998) Extractives. Analytical Methods. Pages 125-148 in Wood chemistry, pulping, and paper making. E Sjöström and R Alén, eds. Springer series in wood science. Springer-Verlag, Berlin, Heidelberg, Germany. 316 pp.nHse CY (1972) Wettability of southern pine veneer by phenol formaldehyde wood adhesives. Forest Prod J 22(1):51-56.nHyvönen A, Piltonen P, Niinimaki J (2005) Biodegradable substances in wood protection. Pages 209-221 in Sustainable use of renewable natural resources—From principles to practices. A Jalkanen and P Nygren, eds. Univ of Helsinki, Department of Forest Ecology Publications, Latokartanonkaari 7, Finland.nInari GN, Pétrissans M, Dumarcay S, Lambert J, Ehrhardt JJ, Šernek M, Gérardin P (2009) Limitation of XPS for analysis of wood species containing high amounts of lipophilic extractives. Wood Sci Technol. (3 July 2010).'>ć M, Živanović R, Stevanović-Janežić T, Dekanski A (1996) Comparison of surface properties of Beech- and Oakwood as determined by ESCA method. Holz Roh Werkst 54:37-41.nJameson GJ, Cerro MCGD (1976) Theory for the equilibrium contact angle between a gas, a liquid and a solid. J Chem Soc Farad T 1(72):883-895.nJohnson RE Jr (1959) Conflicts between Gibbsian thermo-dynamics and recent treatments of interfacial energies in solid-liquid-vapor systems. J Phys Chem 63(10):1655-1658.nKajita H, Skaar C (1992) Wettability of the surfaces of some American softwoods species. Mokuzai Gakkaishi 38:516-521.nKoch P (1972) Utilization of the southern pines. Vol 1 USDA For Serv Agr Handb. 420 pp.nKohonen MM (2006) Engineered wettability in tree capillaries. Langmuir 22:3148-3153.nKubel H, Pizzi A (1981) Protection of wood surfaces with metallic oxides. J Wood Chem Technol 1(1):75-92.nLee S, Shupe TF, Groom LH, Hse CY (2007) Wetting behaviors of phenol- and urea-formaldehyde resins as compatibilizers. Wood Fiber Sci 39(3):482-492.nLi XM, Reinhoudt D, Crego-Calama M (2007) What do we need for a superhydrophobic surface? A review on the recent progress in the preparation of superhydrophobic surfaces. Chem Soc Rev 36:1350-1368.nLiptakova E, Kudela J (1994) Analysis of the wood wetting process. Holzforschung 48:139-144.nLiu Y, German RM (1996) Contact angle and solid-liquid-vapor equilibrium. Acta Mater 44(4):1657-1663.nLu JZ, Wu Q (2006) Surface characterization of chemically modified wood: Dynamic wettability. Wood Fiber Sci 38:497-511.nMaldas DC, Kamdem DP (1998) Surface tension and wettability of CCA-treated red maple. Wood Fiber Sci 30(4):368-373.nMantanis GI, Young RA (1997) Wetting of wood. Wood Sci Technol 31:339-353.nMarian JE (1967) Wood, reconstituted wood and glued laminated structures. Pages 167-280 in Adhesion and adhesives. Vol 2. R Houwink and G Salomon, eds. Elsevier Publishing Co, Amsterdam, London, New York.nMarian JE, Stumbo DA (1962a) Adhesion in wood. Part I: Physical factors. Holzforschung 16(5):134-148.nMarian JE, Stumbo DA (1962b) Adhesion in wood. Part II: Physico-chemical surface phenomena and the thermo-dynamic approach to adhesion. Holzforschung 16(6):168-181.nMarian JE, Stumbo DA, Maxey CW (1958) Glue-joint strength. Forest Prod J 8(12):345-351.nMarian JR (1962). Surface texture in relating to adhesive bonding. In Symposium on properties of surface. ASTM Mater Sci Ser 4: Spec Tech Publ. ASTM, Philadelphia, PA. Pages 122-149.nMarmur A (2009) Solid-surface characterization by wetting. Annu Rev Mater Res 39:473-489.nNguyen T, Johns WE (1978) Polar and dispersion force contributions to the total surface free energy of wood. Wood Sci Technol 12(1):63-74.nNguyen T, Johns WE (1979) The effects of aging and extraction on the surface free energy of Douglas fir and redwood. Wood Sci Technol 13:29-40.nNussbaum RM, Sterley M (2002) The effect of wood extractive content on glue adhesion and surface wettability of wood. Wood Fiber Sci 34(1):57-71.nNzokou P, Kamdem DP (2004) Influence of wood extractives on moisture sorption and wettability of red oak (Quercus rubra), black cherry (Prunus serotina), and red pine (Pinus resinosa). Wood Fiber Sci 36(4):483-492.nNzokou P, Kamdem DP (2005) X-ray photoelectron spectroscopy study of red oak- (Quercus rubra), black cherry- (Prunus serotina) and red pine- (Pinus resinosa) extracted wood surfaces. Surf Interface Anal 37:689-694.nOwens DK, Wendt RC (1969) Estimation of the surface free energy of polymers. J Appl Polym Sci 13(8):1741-1747.nQuété D (2002) Rough ideas on wetting. Physica A 313:32-46.nRowell RM, Banks WB (1985) Water repellency and dimensional stability of wood. Gen Tech Rep FPL-GTR-50. USDA For Serv Forest Products Laboratory, Madison, WI. 24 pp.nSaito M, Yabe A (1983) Dispersion and polar force components of surface tension of some polymer films. Textile Res J 53(1):54-59.nScheikl M, Dunky M (1998) Measurement of dynamic and static contact angles on wood for the determination of its surface tension and penetration of liquids into the wood surface. Holzforschung 52:89-94.nŠernek M (2002) Comparative analysis of inactivated wood surfaces. PhD Dissertation, Virginia Polytechnic Institute State University, Blacksburg VI. 179 pp.nShen Q, Nylund J, Rosenholm JB (1998) Estimation of the surface energy and acid-base properties of wood by means of wetting method. Holzforschung 52:521-529.nShi SQ, Gardner DJ (2001) Dynamic adhesive wettability of wood. Wood Fiber Sci 33(1):56-68.nShibuichi S, Onda T, Satoh N, Tsujii K (1996) Super water-repellent surfaces resulting from fractal structure. J Phys Chem 100:19512-19517.nShupe TF, Hse CY, Choong ET, Groom LH (1998) Effect of wood grain and veneer side on loblolly pine veneer wettability. Forest Prod J 48(6):95-97.nShupe TF, Hse CY, Wang WH (2001) An investigation of selected factors that influence hardwood wettability. Holzforschung 55(5):541-548.nShuttleworth R (1950) The surface tension of solids. Proc Phys Soc A 63(5):444-457.nSinn G, Reiterer A, Stanzl-Tschegg SE (2001) Surface analysis of different wood species using X-ray photoelectron spectroscopy (XPS). J Mater Sci 36:4673-4680.nStumbo DA (1964) Influence of surface aging prior to gluing on bond strength of Douglas-fir and redwood. Forest Prod J 14(12):582-589.nSuchsland K (1957) Influence of the roughness of surfaces on the strength of wood glue bond. Holz Roh Werkst 15(9):385-390.nvan Oss CJ, Good RJ, Chaudhury MK (1988) Additive and nonadditive surface tension components and the interpretation of contact angles. Langmuir 4(4):884-891.nWålinder EP, Gardner DJ (2000) Surface energy of extracted and non-extracted Norway spruce wood particles studied by inverse gas chromatography (IGC). Wood Fiber Sci 32(4):478-488.nWang JZ, DeGroot R (1996) Treatability and durability of heartwood. Gen Tech Rep FPL-GRT-94. USDA For Ser Forest Products Laboratory, Madison, WI. 9 pp.nWang S, Zhang Y, Xing C (2007) Effect of drying method on the surface wettability of wood strands. Holz Roh Werkst 65:437-442.nWellons JD (1980) Wettability and gluability of Douglas-fir veneer. Forest Prod J 30(7):53-55.nWenzel RN (1936) Resistance of solid surfaces to wetting by water. Ind Eng Chem 28:988-994.nWhite LR (1977) On deviations from Young's equation. J Chem Soc, Faraday Trans I 73:390-398.nWhite MS, Ifju G, Johnson JA (1974) The role of extractives in the hydrophobic behavior of loblolly pine rhytidome. Wood Fiber Sci 5(4):353-363.nWilhelmy J (1863) Uber die Abhangigkeit der Kapillatitats-Konstanten des Alkohols von Substanz und Gestalt des Benetzten Festen Korpers. Ann Physik 119:177-217.nWu S (1971) Calculation of interfacial tension in polymer systems. J Polym Sci Pol Lett 34:19-30.nWu S (1979) Surface tension of solids: An equation of state analysis. J Colloid Inteface Sci 71(3):605-609.nZhang HJ, Gardner DJ, Wang JZ, Shi Q (1997) Surface tension, adhesive wettability, and bondability of artificially weathered CCA-treated southern pine. Forest Prod J 47(10):69-72.nZisman WA (1963) Influence of constitution on adhesion. Ind Eng Chem 55(10):19-38.nZwieniecki MA, Holbrook NM (2000) Bordered pit structure and vessel wall surface properties. Implications for embolism repair. Plant Physiol 123:1015-1020.n






Research Contributions