Wood K Plus-Competence Center for Wood Composites and Wood Chemistry, Kompetenzzentrum Holz GmbH, Altenberger Straße 69, A-4040 Linz, Austria.
Institute for Chemistry of Renewable Resources, University of Natural Resources and Life Science Vienna (BOKU), Konrad-Lorenz-Straße 24, A-3430 Tulln an der Donau, Austria.
Molecules. 2020 May 25;25(10):2458. doi: 10.3390/molecules25102458.
Cellulose derivatives have many potential applications in the field of biomaterials and composites, in addition to several ways of modification leading to them. Silanization in aqueous media is one of the most promising routes to create multipurpose and organic-inorganic hybrid materials. Silanization has been widely used for cellulosic and nano-structured celluloses, but was a problem so far if to be applied to the common cellulose derivative "dialdehyde cellulose" (DAC), i.e., highly periodate-oxidized celluloses. In this work, a straightforward silanization protocol for dialdehyde cellulose is proposed, which can be readily modified with (3-aminopropyl)triethoxysilane. After thermal treatment and freeze-drying, the resulting product showed condensation and cross-linking, which was studied with infrared spectroscopy and C and Si solid-state nuclear magnetic resonance (NMR) spectroscopy. The cross-linking involves both links of the hydroxyl group of the oxidized cellulose with the silanol groups (Si-O-C) and imine-type bonds between the amino group and keto functions of the DAC (-HC=N-). The modification was achieved in aqueous medium under mild reaction conditions. Different treatments cause different levels of hydrolysis of the organosilane compound, which resulted in diverse condensed silica networks in the modified dialdehyde cellulose structure.
纤维素衍生物除了有多种改性方法外，在生物材料和复合材料领域也有许多潜在的应用。在水相介质中硅烷化是制备多功能有机-无机杂化材料的最有前途的途径之一。硅烷化已广泛应用于纤维素和纳米结构纤维素，但如果要应用于常见的纤维素衍生物“二醛纤维素”（DAC），即高过碘酸氧化纤维素，则一直存在问题。在这项工作中，提出了一种简单的二醛纤维素硅烷化方法，可以很容易地用（3-氨丙基）三乙氧基硅烷进行修饰。经过热处理和冷冻干燥，得到的产物显示出缩合和交联，这通过红外光谱和 C 和 Si 固态核磁共振（NMR）光谱进行了研究。交联涉及氧化纤维素的羟基与硅醇基团（Si-O-C）以及 DAC 中的氨基和酮官能之间的亚胺型键（-HC=N-）的连接。修饰是在温和的反应条件下在水相介质中进行的。不同的处理导致有机硅烷化合物不同程度的水解，从而导致修饰的二醛纤维素结构中具有不同的缩合硅氧烷网络。
