Study on Control of Liquid Crystal formation for Optically Anisotropic Films Synthesized from Chitin

从我们之前的研究中，我们了解到微晶甲壳素（MC），在盐酸中适度水解，具有NH3+，在水悬浮液和包括丙烯酸单体中都表现出手性向列液晶结构，其中存在各向同性，各向异性和双折射相。通过放置在磁场中或施加剪切强度诱导取向。由取向悬浮液制成的复合聚合物仍具有取向。从极化FT- IR分析，葡萄糖环与磁场方向呈90°取向，酰胺和NH基团与磁场方向呈0°取向。当受剪切强度取向时，葡萄糖环向剪切方向为0°，酰胺和NH基团向剪切方向为90°，施加磁场时则完全相反。目前的研究重点是控制上述合成的复合材料的LC形成。在研究复合材料的二维FT-IR过程中，我们发现甲壳素结构随着温度的升高而发生变化。研究了定向LC膜的二维FT-IR光谱。我们可以观察到氢键（HB）的状态和HB断裂的顺序，依次为[O(6)H…分子间氢键的O(6)]和[O（6’）H…O(7)]、[H…O(3’)分子内HB的O(5)]随着温度的升高。这些结果与X射线衍射分析相吻合。β几丁质的结构也进行了类似的分析。可以认为3515和3376cm-1来源于C(6)OH的分子间HB， 3342cm-1来源于C(3)OH的分子内HB， 3617和1567cm-1分别来源于游离的C(3)OH和C(6)OH。

From the previous our study, the following knowledge was obtained that microcrystalline chitin (MC), which is moderately hydrolyzed in aqueous hydrochloric acid, has NH3+ and shows chiral-nematic liquid crystalline structure in both aqueous suspension and including acrylic acid monomer, where isotropic, anisotropic and birefringence phases are found. The orientation was induced by placing in magnetic field or applying shear strength. The composite polymers made from the orientated suspension still had an orientation. From the polarized FT- IR analysis, glucose ring was orientating 90°, amide and NH groups were orientating 0° against magnetic field direction. When orientated by shear strength, glucose ring was orientating 0°, amide and NH groups were orientating 90° against shear direction, which was totally opposite when applying magnetic field.The present study is focusing on controlling LC formation of the above synthesized composite. In the course of studying 2D FT-IR of composite, it is known that the chitin structure is changing with the increase of temperature. The 2D FT-IR spectrum of orientated LC film was investigated. We can observe the state of hydrogen bonding(HB) and the sequence of breaking HB occurred in the order of [O(6)H... O(6)] of intermolecular hydrogen bonding, and [O(6')H...O(7)], [O(3')H...O(5)] of intramolecular HB with the increase of temperature. These results corresponds with X ray diffraction analysis.The structure of β chitin is similarly analyzed. It can be assigned that 3515 and 3376cm-1 are derived intermolecular HB of C(6)OH, 3342cm-1 the intramolecular HB of C(3)OH, 3617 and 1567cm-1 are due to free C(3)OH and C(6)OH, respectively.