Preparation and Formation Mechanism of Covalent-Noncovalent Forces Stabilizing Lignin Nanospheres and Their Application in Superhydrophobic and Carbon Materials
Preparation and Formation Mechanism of Covalent-Noncovalent Forces Stabilizing Lignin Nanospheres and Their Application in Superhydrophobic and Carbon Materials
复制标题
共价-非共价力稳定木质素纳米球的制备、形成机制及其在超疏水和碳材料中的应用
DOI：
10.1021/acssuschemeng.0c08780
复制
发表时间：
2021-02-26
影响因子：
8.4
通讯作者：
Wu, Yiqiang
中科院分区：
文献类型：
--
作者：
Wang, Hang;Xiong, Fuquan;Wu, Yiqiang
自组装木质素纳米球（LNS）由于为制备木质素衍生的增值产品提供了新的机会而引起了人们的广泛关注。然而，LNS的内部连接通常依赖于弱的分子间力，导致低的耐溶解性和热稳定性。在这项研究中，我们提出了一种简单的方法，通过利用天然特性，即木质素分子在高温刺激下发生不可逆缩合，共价-非共价力稳定的木质素纳米球（HT-LNS）的制造。实验表明，温度的作用导致β-O-4醚和C-α-C-β键以及羟基和-OCH 3木质素分子基团断裂，导致LNS中自由基的形成。此外，大量相邻的分子内和分子间自由基几乎同时通过α-5、β-5、β-β '键等产生化学交联。参与交联反应的木质素分子的量随温度增加而增加，这逐渐将HT-LNS直径从597 nm减小到477 nm，并将最大分解峰从367.7 ℃增强到395.1 ℃。随着处理温度的升高，纳米球在乙醇和四氢呋喃（THF）中的溶解度分别从93.92%下降到10.39%和从98.09%下降到22.45%。HT-LNS可用于制备超疏水涂层，取代非环境友好的二氧化硅纳米颗粒。水接触角和滑动角分别确定为151.9 +/- 1.4度和9.4 +/- 0.5度。此外，HT-LNS用于制备木质素基碳纳米球保持了完美的球形结构，具有微小的石墨化面积，碳原子含量高达94.99%。本研究为绿色材料的开发提供了一个简单有效的技术平台。
Self-assembled lignin nanospheres (LNS) have attracted much attention due to the new opportunities provided for the preparation of value-added products derived from lignin. However, the internal connections of the LNS generally depend on weak intermolecular forces, leading to low solubility resistance and thermostability. In this study, we present a simple method for the fabrication of covalent-noncovalent forces stabilizing lignin nanospheres (HT-LNS) through utilizing the natural characteristic that lignin molecules undergo irreversible condensation under high-temperature stimulation. Experiments demonstrated that the action of temperature resulted in the fracture of beta-O-4 ether and C-alpha-C-beta bonds, as well as hydroxyl and -OCH3 lignin molecule groups, leading to the formation of free radicals in the LNS. In addition, a large number of adjacent intramolecular and intermolecular radicals almost simultaneously generated chemical cross-linking via alpha-5, beta-5, beta-beta' bonds, and so forth. The amount of lignin molecules participating in the cross-linking reaction increased with temperature, which gradually reduced the HT-LNS diameter from 597 to 477 nm and enhanced the maximum decomposition peak from 367.7 to 395.1 degrees C. The solubility of nanospheres in ethanol and tetrahydrofuran (THF) decreased from 93.92 to 10.39% and from 98.09 to 22.45% with increasing treatment temperature, respectively. The HT-LNS can be employed in the preparation of superhydrophobic coatings, replacing non-environmentally friendly silica nanoparticles. The water contact and slide angles were determined as 151.9 +/- 1.4 and 9.4 +/- 0.5 degrees, respectively. Moreover, the application of HT-LNS for the preparation of lignin-based carbon nanospheres maintained a perfect spherical structure with tiny graphitic area and the content of carbon atoms reached up to 94.99%. This study provides a simple and effective technology platform for the development of green materials.