基于聚磷腈薄膜干涉的仿生结构色碳纤维制备及生色机理研究

Automobile lightweight has caused extensive concern due to the environment deterioration and energy crisis. Carbon fiber (CF) reinforced resin composites are recognized as the perfect material for lightweight. However, it is very difficult to color CF by conventional dyes or pigments, because of its special physical and chemical characters. CF and its related materials usually exhibit a drab black. The tired and unexciting look can not satisfy the consumer demand for the products with beautiful and unique appearance. The development and application of CF composites for automobile lightweight may be greatly limited due to lock of consumer acceptance. Therefore, it becomes very important to research and develop an novel coloration technology to prepare colored CF and, further fabricate the colorful composites with structural and functional performances. Inspired by the thin film interference colors of single transparent wing in the insect world, we intends to carry out the study on structural coloration of carbon fibers according to thin polyphosphazene film interference and its coloration mechanism. More specifically, prepare colored CF by introducing a single-layer transparent polyphosphazene film onto CF surface as structural coloration layer via facile in situ self-assembly. The study will focus on the effects of assembly processes on the thickness of polyphosphazene film and the structural color of CF, thus realizing the controllable and efficient preparation of structurally colored CF. Moreover, we will study the the relationship between polyphosphazene film thickness (d) and the reflective wavelength (λ) of the corresponding structural color, verify the consistency of the theoretical reflective wavelength (λ’) and the experimental reflective wavelength (λ), thus revealing the mechanism of structural coloration based on single thin film interference. The project will provide a new method for preparing colored CF. In all, the project is of great significance to offer theoretical guidance for the further development and application of colorful CF and colorful composites with structural and functional performances.

环境恶化与能源危机，使碳纤维复合材料汽车轻量化技术备受重视。然而，由于传统印染不易实现碳纤维的染色，碳纤维及其复合材料通常为单调的黑色，无法满足人们个性化的审美要求。缺乏消费者认可，将不利于推动碳纤维复材轻量化技术的应用。因此，有必要开发一种新技术实现碳纤维的染色，从而制备结构功能一体化的彩色碳纤维复材。受到昆虫薄翅干涉色的启发，本项目拟通过原位化学自组装，在碳纤维表面组装一层聚磷腈薄膜，制备基于单层薄膜干涉的彩色碳纤维，并揭示其生色机理。本项目将重点研究聚磷腈薄膜在碳纤维表面的化学自组装过程对薄膜厚度及结构色的影响，从而实现彩色碳纤维的可控制备；并基于单层薄膜干涉理论，分析结构色波长λ与薄膜厚度d的关系，验证理论波长λ’与实测波长λ的一致性，揭示彩色碳纤维的单层薄膜干涉生色机理。本项目可为碳纤维的染色提供新的方法，将为彩色碳纤维及彩色复合材料的开发与应用提供理论依据，具有重要的研究意义。

采用结构色印染技术对碳纤维进行染色，是近年来碳纤维表界面结构功能一体化改性的研究热点。本项目受到昆虫薄翅干涉色的启发，开发了一种基于薄膜干涉的结构色碳纤维制备方法，通过原位化学自组装，在碳纤维表面组装一层新型交联聚磷腈薄膜，制备得到基于单层薄膜干涉的彩色碳纤维，并揭示了生色机理。具体研究进展及成果如下：（1）开发了模板法制备了一种新颖环基聚磷腈光学薄膜，透光率可达80-90%，阐明了聚磷腈原位生长成膜机制，并发现优良的光学透明性源自磷腈环分子骨架结构；（2）通过原位聚合将聚磷腈薄膜组装到碳纤维表面，当膜层厚度超过200nm时，碳纤维开始呈现彩色，反射波长与薄膜厚度的关系，符合单层薄膜干涉方程。（3）阐明了彩色碳纤维的薄膜干涉机制。以蓝色碳纤维为例，在一定的薄膜厚度下，可见光照射在改性碳纤维表面时，其他波长的光穿过聚磷腈薄膜，被碳纤维的石墨结构吸收，蓝光在聚磷腈表面发生相长干涉，更加强烈的反射回来，所改性碳纤维呈现蓝色。而且，碳纤维提供暗色的背景，使干涉色显得更加明艳。（4）更换共聚单体，发现其他环基聚磷腈薄膜也可通过薄膜干涉实现碳纤维的染色，表明这种基于环基聚磷腈薄膜干涉制备彩色碳纤维的方法具有一定普适性。（5）新型结构色层具有优良的结构稳定性，且有助于修复碳纤维的表面微缺陷，从而改善纤维拉伸强度。而且，蓝色碳纤维的表界面性能可以得到协同优化，蓝色碳纤维增强环氧、尼龙复合材料的界面剪切强度得到明显增强。化学成键、机械锁合、氢键作用是蓝色碳纤维增强树脂基复合材料界面强化的主要因素。（6）新型结构色具有很好的热氧稳定性。空气环境下，300℃能保持结构色不褪色；惰性气体环境下，400℃能保持结构色不褪色。聚磷腈薄膜存在大量的交联结构以及N=P杂环结构，赋予其优异的耐热及耐热氧性能。本项目可为碳纤维的染色提供新的方法，将为彩色碳纤维及彩色复合材料的开发与应用提供理论依据，具有重要的研究意义。