{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,7]],"date-time":"2026-06-07T04:15:42Z","timestamp":1780805742710,"version":"3.54.1"},"reference-count":30,"publisher":"MDPI AG","issue":"4","license":[{"start":{"date-parts":[[2022,2,10]],"date-time":"2022-02-10T00:00:00Z","timestamp":1644451200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Phenol-formaldehyde (PF) resins with well-established molecular sizes are promising treatment agents for wood bulk protection. However, due to the presence of hydroxyl groups on the periphery, the PF oligomers tend to absorb the water, which can lead to water penetration into the wood. To overcome this drawback different PF pre-polymers have been chemically modified with different long-chain fatty acid chlorides (FAC) via esterification. To obtain the modified PF (M-PF) resins, the PF pre-polymers with average molecular weight (Mw) from 266 to 884 g\/mol were esterified with decanoyl, lauroyl, myristoyl, palmitoyl, and stearoyl chloride in pyridine as the reaction medium. Silver birch (Betula pendula) wood specimens (15 \u00d7 70 \u00d7 150 mm3) were coated with M-PF pre-polymer 5% (w\/w) solutions in tetrahydrofuran (THF), and hydrophobic properties of treated birch wood specimens were evaluated using surface contact angle (CA) measurements of water droplets. For all M-PF resin-treated specimens, CA was almost 2\u20132.5 times higher than for untreated wood (45\u00b0) and it remained 80\u2013125\u00b0 after 60 s. The aging properties of M-PF resin-coated birch wood were analyzed using artificial weathering with ultraviolet (UV) light and combination of both UV and water spray. Results clearly confirm, that the hydrophobic properties of M-PF-treated wood has short-term character and will gradually disappear during long-term application in outdoor conditions.<\/jats:p>","DOI":"10.3390\/polym14040671","type":"journal-article","created":{"date-parts":[[2022,2,11]],"date-time":"2022-02-11T02:35:51Z","timestamp":1644546951000},"page":"671","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Birch Wood Surface Characterization after Treatment with Modified Phenol-Formaldehyde Oligomers"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2120-5227","authenticated-orcid":false,"given":"Juris","family":"Grinins","sequence":"first","affiliation":[{"name":"Latvian State Institute of Wood Chemistry, 27 Dzerbenes Str., LV-1006 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2260-6498","authenticated-orcid":false,"given":"Mairis","family":"Iesalnieks","sequence":"additional","affiliation":[{"name":"Latvian State Institute of Wood Chemistry, 27 Dzerbenes Str., LV-1006 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Vladimirs","family":"Biziks","sequence":"additional","affiliation":[{"name":"Institute of Wood Biology and Wood Products, Georg-August University G\u00f6ettingen, B\u00fcsgenweg 4, 37077 G\u00f6ttingen, Germany"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4402-2485","authenticated-orcid":false,"given":"Ineta","family":"Gritane","sequence":"additional","affiliation":[{"name":"Latvian State Institute of Wood Chemistry, 27 Dzerbenes Str., LV-1006 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Guntis","family":"Sosins","sequence":"additional","affiliation":[{"name":"Latvian State Institute of Wood Chemistry, 27 Dzerbenes Str., LV-1006 Riga, Latvia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,2,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"291","DOI":"10.1016\/j.porgcoat.2006.06.010","article-title":"Coating Performance of Finishes on Wood Modified with an N-Methylol Compound","volume":"57","author":"Xie","year":"2006","journal-title":"Prog. Org. Coat."},{"key":"ref_2","first-page":"460","article-title":"Exterior Wood-Coatings and the Glass-Transition Temperature","volume":"178","author":"Schmid","year":"1988","journal-title":"Polym. Paint Colour J."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Evans, P., Vollmer, S., Kim, J., Chan, G., and Kraushaar Gibson, S. (2016). Improving the Performance of Clear Coatings on Wood through the Aggregation of Marginal Gains. Coatings, 6.","DOI":"10.3390\/coatings6040066"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"531","DOI":"10.1007\/s11998-016-9871-8","article-title":"Thermally Modified Scots Pine and Norway Spruce Wood as Substrate for Coating Systems","volume":"14","author":"Altgen","year":"2017","journal-title":"J. Coat. Technol. Res."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2093","DOI":"10.1002\/app.1983.070280621","article-title":"Effect of Grafted UV Stabilizers on Wood Surface Erosion and Clear Coating Performance","volume":"28","author":"Williams","year":"1983","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_6","first-page":"350","article-title":"Quality Assessment of Laminated Window Scantlings from Mixed Tropical Hardwoods after Long-Term Exposure to Weathering","volume":"16","author":"Richter","year":"2004","journal-title":"J. Trop. For. Sci."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"792","DOI":"10.3390\/coatings5040792","article-title":"Coating Acetylated Wood","volume":"10","author":"Rowell","year":"2015","journal-title":"Coatings"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"151","DOI":"10.1007\/s002260000039","article-title":"Weathering of Chemically Modified Wood Surfaces","volume":"34","author":"Evans","year":"2000","journal-title":"Wood Sci. Technol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"749","DOI":"10.1007\/s00226-011-0441-z","article-title":"Effects of Chemical Modification with Glutaraldehyde on the Weathering Performance of Scots Pine Sapwood","volume":"19","author":"Xiao","year":"2012","journal-title":"Wood Sci. Technol."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1515\/HF.2007.008","article-title":"Effect of Treatments with 1,3-Dimethylol-4,5-Dihydroxy-Ethyleneurea (DMDHEU) on the Tensile Properties of Wood","volume":"61","author":"Xie","year":"2007","journal-title":"Holzforschung"},{"key":"ref_11","first-page":"183","article-title":"Weathering Behavior of Dimensionally Stabilized Wood Treated by Heating under Pressure of Nitrogen Gas","volume":"19","author":"Feist","year":"1987","journal-title":"Wood Fiber Sci."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"14","DOI":"10.1080\/17480272.2014.988750","article-title":"Wood Defects during Industrial-Scale Production of Thermally Modified Norway Spruce and Scots Pine","volume":"12","author":"Altgen","year":"2015","journal-title":"Wood Mater. Sci. Eng."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"115","DOI":"10.5552\/drind.2015.1425","article-title":"Evaluation of Weathering of Furfurylated Wood Decks after a 3-Year Outdoor Exposure in Greece","volume":"66","author":"Mantanis","year":"2015","journal-title":"Drvna Ind."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"54","DOI":"10.1016\/j.porgcoat.2016.02.019","article-title":"Application and Artificial Weathering Performance of Translucent Coatings on Resin-Treated and Dye-Stained Beech-Wood","volume":"95","author":"Kielmann","year":"2016","journal-title":"Prog. Org. Coat."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"68","DOI":"10.1108\/03699420010317807","article-title":"Long-term Natural Weathering of Coated ThermoWood","volume":"29","author":"Ahola","year":"2000","journal-title":"Pigment. Resin Technol."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"59","DOI":"10.1007\/BF02697812","article-title":"Performance of Finishes on Wood That Is Chemically Modified by Acetylation","volume":"70","author":"Beckers","year":"1998","journal-title":"J. Coat. Technol."},{"key":"ref_17","first-page":"3","article-title":"Surface Characteristics of Wood as They Affect Durability of Finishes Part 1","volume":"Volume 57","author":"Tarkow","year":"1966","journal-title":"Surface Stabilizazion"},{"key":"ref_18","doi-asserted-by":"crossref","unstructured":"Black, J.M., Laughnan, D.F., and Mraz, E.A. (1979). Forest Products Laboratory Natural Finish, U.S. Department of Agriculture, U.S. Forest Service.","DOI":"10.21236\/ADA079116"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"345","DOI":"10.1515\/hf-2013-0119","article-title":"Improved Weathering Performance and Wettability of Wood Protected by CeO2 Coating Deposited onto the Surface","volume":"68","author":"Lu","year":"2014","journal-title":"Holzforschung"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"395","DOI":"10.1007\/s00226-016-0862-9","article-title":"Highly Hydrophobic and Self-Claning Bulkwood Prepared by Grafting Long-Chain Alkyl onto Wood Cell Walls","volume":"51","author":"Wang","year":"2017","journal-title":"Wood Sci. Technol."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"763","DOI":"10.1007\/s00226-013-0538-7","article-title":"Water Sorption Mechanisms of Commercial Wood Adhesive Films","volume":"47","author":"Wimmer","year":"2013","journal-title":"Wood Sci. Technol."},{"key":"ref_22","unstructured":"(2019). DIN EN ISO 3251:2019 Paints, Varnishes and Plastics; Determination of Non-Volatile-Matter Content, European Committee for Standardization (CEN)."},{"key":"ref_23","unstructured":"(1997). DIN EN ISO 9397: 1997 Plastics\u2014Phenolic Resins\u2014Determination of Free-Formaldehyde Content\u2014Hydroxylamine Hydrochloride Method, European Committee for Standardization (CEN)."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"908","DOI":"10.1515\/hf-2020-0235","article-title":"Evaluation of Water Related Properties of Birch Wood Products Modified with Different Molecular Weight Phenol-Formaldehyde Oligomers","volume":"75","author":"Grinins","year":"2021","journal-title":"Holzforschung"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"367","DOI":"10.1515\/hf-2014-0077","article-title":"Mechanical Stability of Superhydrophobic Epoxy\/Silica Coating for Better Water Resistance of Wood","volume":"69","author":"Liu","year":"2015","journal-title":"Holzforschung"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"105891","DOI":"10.1016\/j.porgcoat.2020.105891","article-title":"Superhydrophobic Coatings on Wood Made of Plant Oil and Natural Wax","volume":"148","author":"Janesch","year":"2020","journal-title":"Prog. Org. Coat."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1016\/j.porgcoat.2013.07.020","article-title":"Biobased Dimer Fatty Acid Containing Two Pack Polyurethane for Wood Finished Coatings","volume":"77","author":"Rajput","year":"2014","journal-title":"Prog. Org. Coat."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"22202","DOI":"10.1021\/acsomega.1c02885","article-title":"Efficient Wood Hydrophobization Exploiting Natural Roughness Using Minimum Amounts of Surfactant-Free Plant Oil Emulsions","volume":"6","author":"Janesch","year":"2021","journal-title":"ACS Omega"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"106008","DOI":"10.1016\/j.porgcoat.2020.106008","article-title":"Bio-Based Coatings from Epoxy Resins Crosslinked with a Rosin Acid Derivative for Wood Thermal and Anti\u2013Fungal Protection","volume":"151","author":"Rosu","year":"2021","journal-title":"Prog. Org. Coat."},{"key":"ref_30","doi-asserted-by":"crossref","unstructured":"Grinins, J., Biziks, V., Marais, B.N., Rizikovs, J., and Militz, H. (2021). Weathering Stability and Durability of Birch Plywood Modified with Different Molecular Weight Phenol-Formaldehyde Oligomers. 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