联苯类液晶改性纤维素膜的制备及其抗紫外性能

Preparation and UV Resistance of Biphenyl Liquid Crystal Modified Cellulose Film

以1,6-二溴己烷、氰基联苯酚和N-甲基咪唑为主要原料,合成含有咪唑基团的联苯类液晶(CbP)。以离子液体1-烯丙基-3-甲基咪唑氯盐(AMIM·Cl)为溶剂,将木浆纤维素(WPC)与CbP共混得到铸膜液,再通过浸渍沉淀相转化技术将铸膜液制成纤维素液晶膜(WPC/CbP)。采用哈克流变仪对溶液性能进行表征,用傅里叶红外光谱(FT-IR)、X-射线光电子能谱(XPS)、差示扫描量热(DSC)等对膜结构和性能进行表征。结果表明,CbP的引入改变了纤维素分子内及分子间的氢键作用,提高了纤维素膜的热稳定性。当CbP在铸膜液中的质量分数为3%时,溶液黏度最低。与纯纤维素膜相比,此WPC/CbP膜的拉伸强度提高了27.56%,紫外光透光率降低了35%左右。

4-(ω-(methylimidazole)hexyloxy)-4′-(cyano)-biphenyl(CbP)was synthesized using 1,6-dibromohexane,cyanobiphenol and N-methyl imidazole as main materials.The wood pulp cellulose solution was prepared by adding CbP to ionic liquid 1-allyl-3-methylimidazolium chloride(AMIM•Cl)as a cellulose solvent,and then its rheological property was tested by Haake rheometer.Wood pulp cellulose liquid crystal films(WPC/CbP)were prepared from the solution by dipping precipitation phase transformation.Fourier infrared spectroscopy(FT-IR)and X-ray photoelectron spectroscopy(XPS)were used to characterize the structure of the film and differential scanning calorimetry(DSC)was used to characterize the thermal stability of the film.The strength of the film was tested by electronic universal tensile testing machine,and the UV resistance of the film was tested by UV-visible near-infrared spectrometer.Results showed that the viscosity of WPC/CbP increased with the increase of the mass fraction of CbP,and the lowest value appeared when the mass fraction of CbP was 3%,in which a liquid crystal phenomenon was observed by polarizing microscope(POM).Compared with WPC film,the thermal stability and tensile strength of the WPC/CbP were improved because of the intramolecular and intermolecular hydrogen bonds of cellulose and CbP.The tensile strength and flexibility of the WPC/CbP were improved by 27.56% and 46.52%,respectively.However,the UV transmittance of the WPC/CbP was reduced by about 35%,indicating its potential application in the field of high strength packaging.