Chemistry and water-repelling properties of phenyl-incorporating wood composites

Abstract

The properties of materials are presented, which are resulting from a combined inorganic-organic modification of wood with phenyltrimethoxysilane or phenyltriethoxysilane in a simple one-step impregnation treatment. The permanent swelling of the wood showed that the precursors entered the cell walls. The inclusion of phenyl groups, manifest by nuclear magnetic resonance spectroscopy, made the resulting wood composites highly hydrophobic, as evidenced by their low wettability and antishrink efficiencies of up to 44%. Impedance spectroscopy indicated that wood methylol groups took part in the condensation reactions with hydrated siloxanes, contributing to the high hydrophobicity and making the added phase resistant to leaching. The composites exhibited high weight percentage gains of up to 52% and ash contents up to 19%. The thermal properties of precursor solutions and products were assessed by differential scanning calorimetry and thermogravimetric analysis and compared with the more common silica precursor, tetraethyl orthosilicate.

Reactivity of Waterlogged Archeological Elm Wood with Organosilicon Compounds Applied as Wood Consolidants: 2D 1H–13C Solution-State NMR Studies

“…On the other hand, we observed demethoxylation of lignin S and G units, which was also seen in our previous FT-IR spectra [ 43 ] and other studies on wood modification with alkoxysilanes [ 57 , 58 ]. From the integration data in Figure 6 , it was evident that the major lignin linkages in all samples treated with alkoxysilanes were much—in some cases two times—higher than that found in the control degraded wood samples, with the exception of the β-β linkage.…”

Cellulose‐Based Biotemplated Silica Structuring

“…As in the namesake construction technology, it can impart structuring and improved mechanical properties to inorganic/brittle materials. [121][122][123][124][125][126] An important finding was that bulking treatments, creating nanometer-scale composites of ceramic phases embedded within the wood cell walls, are most effective in this respect. The technological insight, going as far as being artistically emulated by the tuckpointing technique, was developed without knowledge of its biological analogue.…”

“…The second one is that in a typical processing, consisting of soaking a cellulose template with TEOS and subsequent drying, the hydrolysis step must be considered the time-critical one. Typical exemplary routes are marked blue, [106,122,126,185] green, [120,203] , red, [141,204,205] and brown [107,206] . [192,196] Condensation is further accelerated by water removal, which also leads to the evaporation of unhydrolyzed and non-condensed alkoxide species and lowering material yield.…”

“…[197] , aiding in the onsite hydrolysis of alkoxides. [123,126,[225][226][227][228][229][230] However, even when omitting covalent bonding, studies on the friction between silica and cellulose showed that the interface between the components by Van-der-Waals-forces and possibly hydrogen bonds is very strong, with friction coefficients m of 0.26. [199,200] These considerations, combined with the fact that cellulose structures are highly hygroscopic, form the basis of targeted silica deposition in complex cellulosic scaffolds.…”

“…By the replication of fruit peel, [133] another level of hierarchy is added, namely a pore gradient on the micrometer scale. [126,249] However, this typically leads to a certain amount of material condensation on the surfaces of the templates instead of the desired exclusive filling of the nanometer sized pores. [246][247][248] An issue in siloxane-based biotemplating processes is the overall material yield.…”