Professor Wang Ling Shanghai Jiaotong \”ACS AMI\”: the surface of the hydrophobic organic solvent can cause discoloration of the cellulose film of nanocrystals

A structural color (Structural Color) different from the color pigment (Pigment Color), widely present in the shell beetles, moths wings, bird feathers like organisms in nature. Based on the principle of bionics, and now researchers carried out a lot about the structure of color research. In many materials, the cellulose nanocrystals (Cellulose Nanocrystals, CNCs) because of its unique optical properties, widely available raw materials and simple preparation conditions, etc., gradually been considered one of the best structural color of the material produced. Cause CNCs shows the structure of the presence of a chiral multilayer color three-dimensionally ordered structure in its interior. Since the CNCs inherent hydrophilic properties, its internal structure is susceptible to water damage ordered, thereby affecting the performance of the structure of the color; the biological nature have structural color are hardly affected by water. To overcome the structural color based on the influence of water susceptible of CNCs this shortcoming, Department of Chemistry, Shanghai Jiaotong Wang Ling TF CNCs prepared having a hydrophobic surface film and the organic solvent can cause discoloration. Work related to \”Bio-Inspired Hydrophobic CelluloseNanocrystals Composite Films as Organic Solvent Responsive Structural ColorRewritable Papers\” in the title recently published in the \”ACS Applied Materials & Interfaces\”.

Preparation of 上海交通大学王新灵教授《ACS AMI》:有机溶剂可致变色的表面疏水纤维素纳米晶薄膜
FIG flow 1. CNCs / triblock nanocomposite resin films

This work highlighted the following two material design: one is the three PEG-PPG-PEG CNCs introduced into the block copolymer material, wherein the hydrophilic PEG segment and a hydrophilic aggregation CNCs layer, so that the resin can be stabilized triblock present in the film material, and thus make the film exhibits macroscopically homogeneous color structure, color and structure corresponded to the classical CNCs Bragg equation, pitch exhibited color macroscopic internal chiral multilayer structure is directly linked; and wherein the hydrophobic segment of PPG is introduced into the inter-layer cellulose, help expanding the structure of the color response windows organic solvent, so that the composite membraneIt has visible color red shift in the absorption of organic solvent.

上海交通大学王新灵教授《ACS AMI》:有机溶剂可致变色的表面疏水纤维素纳米晶薄膜
Figure 2. The composite film layer spacing changes CNCs organic solvent after stimulation

Second, the modification of the working hexadecyl trimethoxysilane by one step of hydrophobic surface (hexadecyltrimethoxysilane, HDTMS) chemically grafted successfully at room temperature on the surface of the composite film, the film surface is provided such that the hydrophobic character, the moisture can not affect the performance of the structural color film.

上海交通大学王新灵教授《ACS AMI》:有机溶剂可致变色的表面疏水纤维素纳米晶薄膜
Figure 3. The front hydrophobic surface modification (a) and (b) after the photo film contact angle with water; the composite film by an organic solvent (c) and water (D) through a maximum after UV stimulation migration through the wavelength

composite film prepared in this work to provide a structural color CNCs improve future stability and circulation water responsiveness of a new idea, the future is expected to be applied to hydrophobic repeated writing paper, biomimetic and a screen display field sensor.

上海交通大学王新灵教授《ACS AMI》:有机溶剂可致变色的表面疏水纤维素纳米晶薄膜
Figure 4. As an application example of the composite film (a film surface of the spherical red circle drops)

The reusable paper writing hydrophobic Link: https: //doi.org /10.1021/acsami.0c04785

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