Chemical improvement of surfaces. Part 4: Significantly enhanced hydrophobicity of wood by covalent modification with p-silyl-functionalized benzoates

Abstract

One aim of this work was the chemical modification of surfaces of Scots pine (Pinus sylvestris L.) sapwood veneer chips by covalently bonded substances for improved hydrophobicity. The durable attachment of organosilyl moieties to the surface was in focus. Several benzotriazolyl-activated p-silylated benzoic acid derivatives were applied to the esterification of OH groups at different temperatures and reaction times. The reactions resulted in weight percent gains from 8% to 43% and corresponding quantities of covalently bonded organomaterials of 0.3-2.1 mmol g -1 wood. The hydrophobicity was significantly increased as indicated by contact angles from 121° to 142°. All modified wood samples were analyzed by attenuated total reflection-infrared, contact angle measurements, and X-ray photoelectron spectroscopy.Keywords: attenuated total reflection-IR (ATR-IR), contact angle (CA), covalent fixation, esterification, hydrophobization of wood surface, quantity of covalently bonded organomaterials (QCO), silicon, X-ray photoelectron spectroscopy (XPS)

Novel nicotinoid structures for covalent modification of wood: an environmentally friendly way for its protection against insects

“…39,41 Furthermore, ATR-IR spectroscopy has proven as a very reliable and meaningful method in order to characterize modied wood, which is the reason why this non-destructive method has been chosen to examine all treated samples. 7,[14][15][16][17][18]39,41 Fig . 1 displays the ATR-IR spectra of untreated Scots pine sapwood in comparison to the chemically modied samples 7d-12d.…”

“…The activated neonicotinoids 7c-12c were then applied in the wood modication process, developed previously in our group in order to improve the biological resistance against insects. [14][15][16][17][18] At rst, veneer chips of Scots pine sapwood were used for the modication process. To ensure a high sample throughput, the modications were performed in the "Synthesis 1" liquid system parallel synthesizer.…”

“…General procedure for chemical modication of wood chips following Kaldun et al 17,18 In general, the common amount of 7 mmol of the appropriate wood modifying reagent was applied per 1.00 g of veneer chips of Scots pine sapwood (approx. 10 Â 10 Â 0.7 mm 3 , approx.…”

“…Our group has developed a new and, in contrast to conventional impregnation, more environmentally friendly method for a covalent modication of wood through applying activated benzoic acids. [14][15][16][17][18] By esterication of wood with benzotriazolylactivated carboxylic acids, the material properties can be specically inuenced, while simultaneously retaining its outer appearance. The modication of wood pursues the goal to increase the lifetime of the natural material in order to improve the attractiveness and usability of the material.…”

Durable Modification of Wood by Benzoylation—Proof of Covalent Bonding by Solution State NMR and DOSY NMR Quick-Test

“…Additional improvements such as flame retardancy are in demand and have been put into practice by this concept of covalent attachment of functional organic precursors. Thus far, after initial chemical and analytical investigations in the field of common wood acetylation, we have focused on multipurpose benzoylations applying boron-, carbon-, silicon-, nitrogen-, phosphorus-, and halogen-functionalized activated benzamides as starting materials for the modification (de facto esterification) of wood hydroxyl groups [ 3 , 4 , 5 , 6 , 7 , 8 , 9 ].…”