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, 928 Second Avenue, Hangzhou, Zhejiang, 310018, China.
Macromol Rapid Commun. 2021 Sep;42(17):e2100321. doi: 10.1002/marc.202100321. Epub 2021 Aug 6.
Nonconventional luminogens with persistent room temperature phosphoresce (p-RTP) are attracting increasing attention owing to their momentous significance and diverse technical applications in optoelectronic and biomedical. So far, the p-RTP emission of some amorphous powders or single crystals has been studied in depth. The p-RTP emission of amorphous and fully crystalline states and their emission properties are widely divergent, while the difference of their p-RTP emission mechanism is still controversial. The relevance between crystallinity change and p-RTP properties is rarely studied. Furthermore, there is almost no research on the photoluminescence (PL) property change and emission mechanism under the crystal form transformation of semi-crystalline polymer. Herein, microcrystalline cellulose (MCC) is chosen as a model compound to explore its crystallinity and the change in luminescence during the crystal form transformation to make up for this gap. By precisely adjusting the crystallinity and crystal cellulose conversion of MCC, the changing trend of quantum efficiency, and p-RTP lifetime is consistent with the change of crystallinity, and the cellulose I may be more beneficial to PL emission than cellulose II. Clustering-triggered emission mechanism can reasonably explain these interesting photophysical processes, which also can be supported by single-crystal analysis and theoretical calculations.
具有室温磷光（p-RTP）的非传统发光体由于其在光电和生物医学领域的重要意义和多样化的技术应用而引起了越来越多的关注。迄今为止，一些非晶态粉末或单晶的 p-RTP 发射已经得到了深入研究。非晶态和完全晶态的 p-RTP 发射及其发射性质广泛不同，而它们的 p-RTP 发射机制的差异仍存在争议。结晶度变化与 p-RTP 性质之间的相关性很少被研究。此外，对于半晶态聚合物的晶型转变下的光致发光（PL）性质变化和发射机制的研究几乎没有。本文选择微晶纤维素（MCC）作为模型化合物，探索其结晶度以及在晶型转变过程中发光的变化，以弥补这一空白。通过精确调节 MCC 的结晶度和晶体纤维素转化率，量子效率和 p-RTP 寿命的变化趋势与结晶度的变化一致，纤维素 I 可能比纤维素 II 更有利于 PL 发射。聚集触发发射机制可以合理地解释这些有趣的光物理过程，单晶分析和理论计算也可以支持这一机制。
