CNC液晶纺丝过程之手性结构颜色保留机制

Material scientists hve a dream to frabricate a highlighted, never fading colorful dress like a beautiful feather of peacock. Recently, this kind of structure-color materials was made from cellulose nanocrystals extracted from natural resources.It seems that it will be a great breakthough to realize our dream. However, even 55 years'research was focused on CNC liquid crystal, it is still unclear that how to retain the cholesteric liquid crystal from suspension to the film. Till now no research work was focused on fabricating reflected visible iridesent fiber based on CNC perhaps because of the fragility and poor fabrillation of CNCs with high crystallinity. To solve above mentioned question, we biomimic the spinning process of natural silk based on our previous research based on CNC liquid crystal and spinning of natural polymers. In the spining process we will control the structure of liquid crystal suspension and solidified film or fiber, monitor or characterize the transition of strcuture and properties of CNC, put forward the glass transition mechanism during the solidification. And then we will improve the spinning technique to make it suitable for fibrillating CNC chiral structure-colorful bifers, furthermore we will prepare porous photonic crystal fiber using CNC as templates. All in all, in this project, we will set up the fabricating methods of CNC chiral optical fiber and establish the structure-color model of liquid crystal of CNC and try to develop the photonic fiber or liquid crystal fiber for wide application in the field of fabric, sensor, secret fiber and so on.

仿制如孔雀羽毛般亮丽而不褪色、五彩缤纷的外衣一直是材料科学家的梦想。从可再生纤维素中提取的CNC可以组装成相似的结构颜色薄膜，这似乎为梦想开辟了一个突破口。尽管长达55年的研究，CNC液晶从悬浮液到彩色膜的固化机理至今仍然模糊，加之CNC高结晶性和固化液晶难保留等导致材料易脆且成纤性差，给CNC液晶纺丝带来了巨大的困难，造成CNC彩色液晶纤维研究开发的缺失。本项目结合本课题组之前CNC自组装液晶膜的研究基础，仿生蚕丝液晶纺丝的过程，改进纺丝方法，控制内外场作用下前驱液的液晶结构，纺制具有手性特征的彩色微纳米液晶纤维，由之利用模板法制备光子晶体纤维。经由监测液晶固化过程中的结构-颜色变化和玻璃转变，提出CNC纤维的手性结构颜色保留机制。通过本项目的基础理论研究，我们将进一步实现CNC彩色纤维在彩色织物、传感器、防伪隐身材料等方面的应用，建立起手性结构颜色纤维这一新材料的应用理论基础。

CNC 液晶从悬浮液到彩色膜的结构色和固化机理至今仍然模糊，加之CNC 高结晶性和固化液晶难保留等导致材料易脆且成纤性差，给 CNC 液晶纺丝带来了巨大的困难。本项目目前已经确立纤维素纳米晶胆甾相液晶的结构颜色机制，实现胆甾相液晶材料结构颜色的控制移动；并实现了CNC胆甾相液晶气体的可视传感。通过添加无机离子，有机多元醇以及纤维素衍生物和亲水高分子等方式实现对CNC的力学性能改善，建立了对柔性胆甾相液晶膜、纤维、涂料等材料的可控增塑和结构色调制。针对液晶纤维纺丝过程中液晶相转变和消失，建立了液晶在剪切力、电场力，离心力、静电作用下CNC的相变机制，为实现可控相转变下CNC胆甾相液晶纤维的制备和应用奠定理论基础。

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