纤维素纳米晶/金纳米粒子复合虹彩薄膜的制备与表征

Preparation and Characterization of Cellulose Nanocrystal/Gold Nanoparticle Composite Iridescent Film

以滤纸为原料,采用浓硫酸水解法制备纤维素纳米晶(CNCs),以柠檬酸钠还原法制备金纳米粒子(GNPs),并将GNPs与CNCs以不同质量比共混制备CNCs/GNPs复合虹彩薄膜;并在CNCs/GNPs体系中添加果糖,研究了果糖对等离子吸收共振效应的影响。采用透射电镜、反射光谱、扫描电镜、偏光显微镜、红外光谱、X射线衍射、紫外-可见光谱和圆二色谱对复合薄膜进行分析,探讨了GNPs与CNCs以不同质量比复合时的结构与性能,以及果糖对体系的影响。研究结果表明:CNCs在成膜过程中发生了自组装,形成了左旋的手性层状液晶结构;复合薄膜具有明显的虹彩颜色,具有周期性层状结构和指纹织构,添加GNPs没有改变CNCs本身的官能团,但复合膜具有明显的等离子共振吸收峰并发生蓝移。添加果糖会使薄膜颜色产生红移现象的同时促进GNPs更加均匀地分散,从而增强GNPs的等离子共振吸收效应。GNPs和果糖的加入不会改变CNCs的晶型结构,对纤维素的结晶度也没有影响。

The filter paper was used as raw material to prepare cellulose nanocrystals(CNCs)and gold nanoparticles(GNPs)were prepared by sodium citrate reduction method.Subsequently,CNCs/GNPs composite iridescence was prepared by blending GNPs and CNCs at different mass ratios,following by adding fructose to the above system in order to study the influence of fructose on the plasmon absorption resonance effect.Then,the composite films were analyzed by transmission electron microscopy(TEM),reflection spectroscopy,scanning electron microscopy(SEM),polarized light microscopy,infrared spectroscopy,X-ray diffraction(XRD),ultraviolet-visible(UV)spectroscopy and circular dichroism(CD).The results showed that CNCs have self-assembled during the film formation process and formed a left-handed chiral layered liquid crystal structure;the composite film had obvious iridescent color,periodic layered structure and fingerprint texture.The addition of GNPs did not change the CNCs itself,but the composite membrane had obvious plasmon resonance absorption peak and blue-shifted.Moreover,the addition of fructose could make the color of the film red-shifted and promote the more uniform dispersion of GNPs,thereby enhancing the plasmon resonance absorption effect of GNPs.Particularly,the addition of GNPs and fructose did not change the crystal structure of CNCs,nor did it affect the crystallinity of cellulose.