Improved order parameter (alignment) determination in cellulose nanocrystal (CNC) films by a simple optical birefringence method
Improved order parameter (alignment) determination in cellulose nanocrystal (CNC) films by a simple optical birefringence method
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DOI：
10.1007/s10570-017-1250-9
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发表时间：
2017-05-01
期刊：
影响因子：
5.7
通讯作者：
Youngblood, Jeffrey
中科院分区：
文献类型：
--
作者：
Chowdhury, Reaz A.;Peng, Shane X.;Youngblood, Jeffrey
研究了基于纤维素纳米晶(Cnc)薄膜晶体取向的双折射来确定晶体取向。我们的主要研究重点是建立一种简单、低成本的实验技术，使用标准的UV-Vis光谱仪来确定各向同性和各向异性组态的有序参数(S)。利用具有不同剪切速率的剪切流制备了不同阶数(S：0-0.95)的自立式数控薄膜。测量了CNC膜在明场和暗场下交叉偏振器之间的透射光强度，确定了线性二向色性比，并利用该比计算了不同晶型的有序参数。将二维X射线衍射结果与双折射技术进行了比较，以探索短程非晶有序的存在，这在高阶参数(S和GT；0.60)样品中具有重要意义。因此，新的双折射技术可以使用更常见和更低成本的设备，以更容易的方法获得更准确的有序参数测量。
Birefringence, based on the crystal orientation of a cellulose nanocrystal (CNC) film, has been investigated for the determination of crystal orientation. The prime focus of our study is to establish a simple and low-cost experimental technique using a standard UV-Vis spectrometer to determine the order parameter (S) for both isotropic and anisotropic configurations. Self-standing CNC films of various order parameters (S: 0-0.95) were prepared using shear flow with varying shear rates. The transmitted light intensity of CNC films between cross polarizers for the bright and dark fields were measured to determine the linear dichroitic ratio, which were used to calculate the order parameters of different crystalline arrangements. Two-dimensional X-ray diffraction results were compared to the birefringence technique to explore the presence of short-range amorphous order, which is significant in higher order parameter (S > 0.60) specimens. Thus, the new birefringence technique was shown to obtain a more accurate measurement of order parameter with an easier method using more common and lower cost equipment.