Zhou Qing, Liu Man, Li Chuchu, Lu Shijia, Lei Bin, Jiang Jiantang, Yin Ying, Zhang Yuanchao, Shen Yifeng
Engineering Research Center for Eco-Dyeing and Finishing of Textiles, Key Laboratory of Advanced Textile Materials and Manufacturing Technology, Ministry of Education, College of Textile Science and Engineering (International Institute of Silk), Zhejiang Sci-Tech University, Hangzhou, China.
Dali Silk (Zhejiang) Co., Ltd., Dali Science and Technology Park, Nanyan Provincial High-tech Development Zone, Shaoxing, China.
Front Chem. 2022 Jun 28;10:805252. doi: 10.3389/fchem.2022.805252. eCollection 2022.
The alkali mercerizing process of semicrystalline cotton fiber (CF) is widely used in the printing and dyeing industry. The crystallinity change in the mercerizing process has been studied and certain laws have been obtained, but there is still a certain distance between the theoretical research results and the practical applications. CF is almost composed of cellulose, combined with the photoluminescence (PL) phenomenon of cellulose; herein, the varying crystallinity is correlated with its PL behavior after being treated with different concentrations of NaOH. In line with the characteristics of nonconventional luminogens, CF enjoys excitation-dependent emission and persistent room temperature phosphorescence (p-RTP) behavior. The emission spectra of all samples under the same excitation wavelength indicate that the change of CF crystallinity has a significant impact on its fluorescence and p-RTP emission. As the concentration of NaOH increases, the varying trend of quantum efficiency (QY) is consistent with the changed crystallinity of CF. Interestingly, the lifetime of p-RTP is exactly the opposite of the crystallinity change law. Clustering-triggered emission (CTE), crystallization-Induced Phosphorescence (CIP) mechanism, and the swelling due to hydrated sodium ions can reasonably explain these interesting photophysical processes, which also can be supported by theoretical calculations. The above studies have basically clarified the inherent law between the crystalline change of CF and the PL emission behavior during the alkali treatment process, which can be used as a theoretical reference for real-time monitoring of CF crystallinity changes using the spectral method in the actual cotton mercerizing process.
半结晶棉纤维（CF）的碱丝光工艺在印染行业中广泛应用。人们已经对丝光过程中的结晶度变化进行了研究并得出了一定规律，但理论研究结果与实际应用之间仍存在一定差距。CF几乎完全由纤维素组成，结合纤维素的光致发光（PL）现象，在此研究了不同浓度NaOH处理后CF的结晶度变化与其PL行为之间的关系。符合非常规发光体的特性，CF具有激发依赖发射和持久室温磷光（p-RTP）行为。相同激发波长下所有样品的发射光谱表明，CF结晶度的变化对其荧光和p-RTP发射有显著影响。随着NaOH浓度的增加，量子效率（QY）的变化趋势与CF结晶度的变化一致。有趣的是，p-RTP的寿命与结晶度变化规律正好相反。聚集诱导发射（CTE）、结晶诱导磷光（CIP）机制以及水合钠离子引起的溶胀可以合理地解释这些有趣的光物理过程，理论计算也支持这一点。上述研究基本阐明了CF在碱处理过程中结晶变化与PL发射行为之间的内在规律，可为实际棉丝光过程中利用光谱法实时监测CF结晶度变化提供理论参考。
