Wettability and spectroscopic characterization of silylated wood samples

Abstract

Surfaces of three European wood species (namely, English oak, Hungarian oak, and Scots pine) and two tropical wood species (namely, teak and cloves) were silylated with dichlorodimethylsilane (DDS), dichlorodiphenylsilane (DPS) and octadecyltrichlorosilane (OTS) in the first step, and with chlorotrimethylsilane (CTMS) as a monofunctional reagent in a second step. Attenuated total reflection-Fourier transform infrared (ATR-FT-IR) and electron spectroscopy for chemical analysis (ESCA) measurements were performed in order to characterize the surface composition of the treated samples. The progress of surface modification was also monitored by contact angle measurements of different test liquids (water, formamide and diiodomethane). The water contact angles were found to be in the range of 808 to 1458. The most hydrophobic surface was obtained by two-step silylation by OTS and CTMS (water contact angles were between 1318 and 1408). Interestingly, the hydrophobicity of DDS-treated samples showed a significant decrease after additional silylation by CTMS. The surface free energy values were evaluated in terms of the Lifshitz-van der Waals/acid-base theory. The results obtained by the surface analytical methods (i.e. FT-IR and ESCA measurements) were compared with the contact angle data. These results suggest that in the case of DDS-treated samples, CTMS molecules substitute partly the DDS molecules, thus only physisorption of the silylating agents is supposed at room temperature.

Creation of superhydrophobic wood surfaces by plasma etching and thin-film deposition

“…Over the years, various methods have been reported to modify wood hydrophobicity, including acetylation [11], metal oxide deposition [12][13][14], modification with chlorosilanes [15,16], and silicone polymer grafting [8]. The majority of these methods require the use of wet chemistry, which in many instances causes environmental concerns due to the use of solvents and resulting waste streams, and economical challenges resulting from the need for additional processing steps and large consumption of chemicals due to sorption into the porous wood substrate.…”

Determination of adhesive energy at the wood cell-wall/UF interface by nanoindentation (NI)

“…Then the samples were rinsed with n-hexane and air-dried. 2) A set of specimens was subjected to a two-step treatment with octadecyltrichlorosilane (OTS) and chlorotri methylsilane (CTMS) (Mohammed -Ziegler et al 2006 ). The procedure consists of a 1 st silylation step, in which the specimens are treated in a 1 % (v/v) n-hexane solution of OTS for 1 h under continuous stirring with subsequent rinsing with n-hexane.…”

“…1) Silylation with dichlorodiphenylsilane (DPS) following exactly the procedure of Mohammed -Ziegler et al (2006) . Briefl y, the specimens were treated for 1 h under continuous stirring in a 1 % (v/v) n-hexane solution of DPS.…”

Impact of organosilicon treatments on the wood-water relationship of solid wood

“…After Figure 4 Range of contact angles (8) in function of time for specimens impregnated with organosilicons W3 or S1 and exposed outside for 3 years. therefore create a water repellent effect on wood (Mohammed-Ziegler et al 2006). …”