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首页> 外文期刊>Materials Science Research International >Design and Function of Lignin-Based Recyclable Composites
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Design and Function of Lignin-Based Recyclable Composites

机译：木质素基可回收复合材料的设计与功能

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Through the phase-separation system composed of phenols and concentrated acid, the phenol components are selectively hybridized into C1-positions of phenylpropane units of native lignin to give 1,1-bis(aryl)propane-type linear polymers (lignophenols) quantitatively. Lignophenols have unique properties such as high phenolic activity and obvious phase transition. Furthermore, the functionality of lignophenols was able to be controlled using the intramolecular switching function: Under alkaline condition, C1-phenols in lignophenols nucleophilically attack adjacent C2 as switching devices, followed by the cleavage of aryl ether linkages. In ligno-p-cresol and ligno-2,4-dimethylphenol with similar switching functionality and structural characteristics, ligno-p-cresol was highly hy-droxymethylated (HM) on the cresolic nucleus to give network-living pre-polymer. On the other hand, ligno-2,4-dimethylphenol having reactive sites mainly on the terminal unit gave linear-living pre-polymers: The structures of polymerized lignophenols were controlled by mixing ratio of HM-ligno-p-cresol and HM-ligno-2,4-dimethylphenol or by the hybridization ratio of p-cresol and 2,4-dimethylphenol in lignophenols followed by hydoxymethylation. The resulting polymer chains were cleaved at the switching points to give low molecular weight subunits by the switching function. Recyclable composites were prepared by the combination of cellulose and HM-lignophenol (the mixing ratio of HM-ligno-p-cresol to HM-ligno-2,4-dimethylphenol was 1:0, 1:1, 0:1, respectively). The composites had glossy surfaces and looked like wood. The dimensional stability of composites was improved significantly with increasing mixing ratio of HM-ligno-p-cresol to HM-ligno-2,4-dimethylphenol. Using the switching functionality of lignophenol, the composites were re-separated into lignophenols with low molecular weight and cellulose.
机译：通过由苯酚和浓酸组成的相分离系统，苯酚组分被选择性地杂交到天然木质素的苯基丙烷单元的C1位，定量地得到1,1-双（芳基）丙烷型线性聚合物（木质酚）。木质素酚具有独特的性质，例如高酚活性和明显的相变。此外，可以使用分子内转换功能来控制木质素酚的功能：在碱性条件下，木质素酚中的C1-酚亲核性攻击相邻的C2作为交换装置，然后裂解芳基醚键。在具有相似的开关功能和结构特征的木质素-对-甲酚和木质素-2,4-二甲基苯酚中，木质素-对甲酚在甲酚核上被高度羟甲基化（HM），得到网络活性的预聚物。另一方面，主要在末端单元上具有反应性位点的木质素-2,4-二甲基苯酚产生线性活性的预聚物：聚合的木质素酚的结构通过HM-木质素-对甲酚和HM-木质素的混合比来控制。 -2,4-二甲基苯酚或对甲酚和2,4-二甲基苯酚在木质素酚中的杂交比例，然后进行羟甲基化。通过转换功能，将所得的聚合物链在转换点处裂解以得到低分子量的亚单位。通过纤维素和HM-木质酚的组合制备可回收的复合材料（HM-木质素-对甲酚与HM-木质素-2,4-二甲基酚的混合比分别为1：0、1：1、0：1） 。复合材料表面光滑，看上去像木头。随着HM-木质素-对甲酚与HM-木质素-2,4-二甲基苯酚混合比的增加，复合材料的尺寸稳定性得到显着改善。使用木质素酚的转换功能，将复合物重新分离为低分子量的木质素酚和纤维素。

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