Abstract
The present study contributes to the controversial discussion in the literature whether Si–O–C bonds in wood–silica–gel composites exist. 13C NMR is a suitable method to proof such bonds. Because of the low concentration of 13C isotopes in natural wood, 13C cellulose was used as 13C-enriched substitute. A tailored sol for the impregnation of that cellulose was chosen by liquid 29Si NMR pre-investigations of various sols whose reactivity and stability were time-dependently analysed. It is based on a sub-stoichiometric hydrolysis of tetraethoxysilane (TEOS) with 1 mol water per mol TEOS. Thermal analyses were performed to show a comparability of the thermal behaviour of wood–silica–gel and cellulose–silica–gel composites. There are two strong hints of the existence of stable Si–O–C bonds: (1) by thermal analysis, a shift in the fire behaviour of 100 K can be observed with a change in pyrolysis behaviour of the composite and (2) the proof by REDOR NMR that a dipolar coupling between 29Si and 13C nuclei exists.
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References
Bennett AE, Rienstra CM, Auger M, Lakshmi KV, Griffin RG (1995) Heteronuclear decoupling in rotating solids. J Chem Phys 103:6951–6958
Brinker CJ, Scherer GW (1990) Sol–gel science: the physics and chemistry of sol–gel processing. Academic Press, ISBN 0-12-134970-5
Brinker CJ, Sehgal R, Raman N, Schunk PR, Headley TJ (1994) Polymer approach to supported silica membranes. J Sol Gel Sci Technol 2:469–476
Cook RL, Langford CH, Yamdagni R, Preston CM (1996) A modified cross-polarization magic-angle spinning C-13 NMR procedure for the study of humic materials. Anal Chem 68:3979–3986
Donath S, Militz H, Mai C (2004) Wood modification with alkoxysilanes. Wood Sci Technol 38:555–566
Drzal LT, Askeland P, Lu J (2008) Surface modification of microfibrillated cellulose for epoxy composite applications. Polymer 49:1285–1295
Engelhardt G, Michel D (1987) High-resolution solid-state NMR of silicates and zeolites. John Wiley and Sons, Chichester
Gullion T, Schaefer J (1989) Development of REDOR rotational-echo double-resonance NMR. J Magn Reson 81:196–200
Hill CAS, Papadopoulos AT (2001) A review of methods used to determine the size of the cell wall micro voids of wood. J Inst Wood Sci 15:337–345
Mahltig B, Swaboda C, Roessler A, Böttcher H (2008) Functionalising wood by nanosol application. J Mater Chem 18:3180–3192
Mai C, Militz H (2004) Modification of wood with silicon compounds. Inorganic silicon compounds and sol–gel systems: a review. Wood Sci Technol 37:339–348
Mantanis G, Papadopoulos A (2010) The sorption of water vapour of wood treated with a nanotechnology compound. Wood Sci Technol 44:515–522
Miyafuji H, Saka S (1996) Wood-inorganic composites prepared by sol–gel processing. 5. Fire-resisting properties of the SiO2-P2O5-B2O3 wood-inorganic composites. Mokuzai Gakkaishi 42:74–80
Miyafuji H, Saka S (1999) Topochemistry of SiO2 wood-inorganic composites for enhancing water-repellency. Mater Sci Res Int 5(4):270–275
Miyafuji H, Saka S (2001) Na2O–SiO2 wood-inorganic composites prepared by sol–gel process and their fire-resistant properties. J Wood Sci 47:483–489
Miyafuji H, Saka S, Yamamoto A (1998) SiO2-P2O5-B2O3 wood inorganic composites prepared by metal oxide oligomers and their fire-resisting properties. Holzforschung 52:410–416
Neder RB, Burghammer M, Grasl T, Schulz H, Bram A, Fiedler S (1999) Refinement of the kaolinite structure from single-crystal synchrotron data. Clays Clay Miner 47:487–494
Ogiso K, Saka S (1994) Wood-inorganic composites prepared by sol–gel process IV: effects of chemical bonds between wood and inorganic substances on property enhancement. Mokuzai Gakkaishi 40:1100–1106
Reinsch S, Böcker W, Bücker M, Seeger S, Unger B (2002) Development of wood-inorganic composites with enhanced properties and environmental stability. Proceedings of 4th international wood and fibre composites symposium, Kassel: 50-1–50-6
Rosenthal M, Bues C-T (2010) Longitudinal penetration of silicon dioxide nanosols in wood of pinus sylvestris. Eur J Wood Prod 68:363–366
Rudolph M (1987) Kinetik der Hydrolyse und Kondensation von Alkoxysilanen. Ph.D. thesis 1987, University of Ulm, Germany
Saka S, Miyafuji H (2005) Application of sol–gel processing to wood-inorganic composites. in handbook of sol–gel science and technology: vol 3, chap 27, Kluwer Academic Publishers, 577–595
Saka S, Sasaki M, Tanahashi M (1992) Wood-inorganic composites prepared by sol–gel processing I: wood-inorganic composites with porous structure. Mokuzai Gakkaishi 38:1043–1049
Saka S, Miyafuji H, Tanno F (2001) Wood-inorganic composites prepared by the sol–gel process. J Sol Gel Sci Technol 20:213–217
Sèbe G, Brook MA (2001) Hydrophobization of wood surfaces: covalent crafting of silicone polymers. Wood Sci Technol 35:269–282
Singh T, Singh AP (2012) A review on natural products as wood protectant. Wood Sci Technol 46:851–870
Trepte J (1999) Silicium-nanosole für den holzschutz. nano III/99; nano-technology center of competence, “ultrathin functional films” in Fraunhofer IWS, Dresden, Germany
Unger B, Jancke H, Hähnert M, Stade H (1994) The early stages of the sol–gel processing of TEOS. J Sol Gel Sci Technol 2:51–56
Unger B, Rurack K, Müller R, Jancke H, Resch-Genger UJ (2005) Microscopic vs. macroscopic evolution of SiO2 sols and gels employing a tailor-made fluorescent reporter dye. Mater Chem 15:3069–3083 ISSN 0959–9428
Unger B, Bücker M, Reinsch S, Hübert T (2013) Chemical aspects of wood modification by sol–gel derived silica. Wood Sci Technol 47:83–104
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Bücker, M., Jäger, C., Pfeifer, D. et al. Evidence of Si–O–C bonds in cellulosic materials modified by sol–gel-derived silica. Wood Sci Technol 48, 1033–1047 (2014). https://doi.org/10.1007/s00226-014-0657-9
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DOI: https://doi.org/10.1007/s00226-014-0657-9