可制备透明紫外阻隔膜的可聚合木质素的研究

Study on Polymerizable Lignin for Preparing Transparent UV Blocking Films

作为制浆造纸业的副产物,由于溶解性太差,工业木质素在大规模、增值利用方面一直面临巨大挑战。本文通过10⁃十一碳烯酰氯(11ene)与脱碱木质素(DAL)的羟基进行酯化反应,合成了三种具有不同取代度的可聚合物木质素(DAL⁃11ene⁃1、DAL⁃11ene⁃2和DAL⁃11ene⁃3)。采用^(1)H NMR、FTIR和UV⁃Vis吸收光谱对其结构进行了表征;并由^(31)P NMR测定了羟基取代度。研究发现,引入取代基后三种目标产物在商用丙烯酸酯单体1,6⁃己二醇二丙烯酸酯(HDDA)中的溶解性均获得不同程度的改善,其中取代度最高的DAL⁃11ene⁃3在HDDA中的添加量可以达到10(wt)%。将DAL⁃11ene⁃3以1(wt)%~5(wt)%的比例掺入预聚物配方中,经光固化制备了五种聚合物薄膜(DLE1~DLE5),其中掺入量最高的DLE5膜的紫外阻隔效果最好,可以阻挡超过95%的UVA光并且具有较好的光稳定性。此外,五种薄膜在可见光区具有很高的透过率。进而,将预聚物键合到烷基化的玻璃基底上,制备了五种相应的玻璃涂层,并对其表面润湿性和机械性能进行了评价。玻璃基底上的聚合物涂层表现出更高的硬度和模量以及更疏水的性能。这项工作提出了一种可行的方案来实现木质素的增值利用并有望应用于生活中的各类防紫外薄膜或涂层。

As the by⁃product of the pulp and paper industry,industrial lignin has been facing great challenge in large⁃scale and value⁃added utilization due to its poor solubility.In this paper,three polymerizable lignin(DAL⁃11ene⁃1,DAL⁃11ene⁃2 and DAL⁃11ene⁃3)with different degrees of hydroxyl substitution were synthesized by esterification of 10⁃undecyenoyl chloride(11ene)and the hydroxyl groups of dealkaline lignin(DAL).Their structures were characterized by ^(1)H NMR,FTIR and UV⁃Vis spectra.The degree of hydroxyl substitution was determined by ^(31)P NMR.It was found that the solubility of the three target products with different degrees of substitution was improved,among which the addition amount of DAL⁃11ene⁃3 with the highest degree of substitution in 1,6⁃Hexanediol diacrylate(HDDA)could reach 10(wt)%.Five polymer films(DLE1~DLE5)were prepared by adding 1(wt)%~5(wt)%DAL⁃11ene⁃3 into prepolymer formulations and photocuring.Among them,DLE5 film with the highest addition amount had the best UV blocking property,which could block more than 95%of UVA light and had good photostability.In addition,the five films exhibited high transmittance in the visible light region.Furthermore,five corresponding glass coatings were prepared by bonding the prepolymers to alkylated glass substrates,and their surface wettability and mechanical properties were evaluated.These coatings on glass substrates exhibited higher hardness and modulus,and more hydrophobic properties.This work puts forward a feasible scheme to realize the value⁃added utilization of lignin,which is expected to be applied to various UV blocking films or coatings in life.