采用硫酸水解联合高压均质化，制备了生物质纳米纤维素晶体（CNC），经超声波处理诱导自组装形成手性排列，并研究了其自组装膜的结构色特征。扫描电子显微镜（SEM）和透射电子显微镜（TEM）观察显示，纤维素纳米晶体尺寸均一，多呈短棒状，具备形成手性排列的结构基础。表面电势、流变性能及偏光特性研究表明，水解时硫酸浓度越高，生成的CNC表面Zeta电位绝对值越大，黏度越大，越利于形成手性排列，从而产生良好的偏光性；CNC经超声波处理有助于自组装成“光子晶体”，显示出较好的结构色。
The cellulose nanocrystals(CNC) of uniform size are prepared by the high-pressure homogenization coupled with the sulfuric acid hydrolysis pretreatments in this paper. The CNC suspension is self-assembled to form a unique chiral arrangement with the ultrasonic treatment. The self-assembled CNC film is shaped further to possess novel structural color characteristics. The size and the morphology of the prepared CNCs are determined by the transmission electron microscope(TEM) and the scanning electron microscope(SEM). The CNCs are rod-like mostly and fully separated in suspension with highly uniform size, and possess the structural basis to form the chiral arrangement. From the surface potential, the sticky flow characteristics and the polarization characteristics, it is shown that at a higher sulfuric acid concentration, the zeta potential value and the viscosity of the CNC suspension are increased, which makes it easier to form the chiral arrangement. Further studies conclusively show that the CNCs are liable to self-assemble into the chiral arrangement after the ultrasonic treatment to exhibit excellent structural color characteristics.
[1] 李家文.生物结构色机理及仿生构色研究[D].合肥:中国科学技术大学,2011.Li Jiawen.Research on mechanism and bionic structure color color biological structures[D].Hefei:University of Scienceand Technology of China,2011.
[2] 刘志福.基于光子晶体的结构色纤维制备及其显色性能研究[D].上海:东华大学,2013.Liu Zhifu.Based on the structure of the photonic crystal color fiber preparation and color performance research[D].Shanghai:Donghua University,2013.
[3] Marchessault R H,Morehead F F,Walter N M.Liquid crystal systems from fibrillar polysaccharides[J].Nature,1959,184:632-633.
[4] Shopsowitz K E,Qi H,Hamad W Y,et al.Free-standing mesoporous silica films with tunable chiral nematicstructures[J].Nature,2010,468:422-425.
[5] Lagerwall J P F,Schütz C,Salajkova M,et al.Cellulose nanocrystalbased materials:from liquid crystal self-assembly and glass formation to multifunctional thin films[J].NPG Asia Materials,2014,6(1):80-85.
[6] Orts W J,Godbout L,Marchessault R H,et al.Enhanced ordering of liquid crystalline suspensions of cellulose microfibrils:A small angle neutron scattering study[J].Macromolecules,1998,31(17):5717-5725.
[7] Yi J,Xu Q,Zhang X,et al.Temperature-induced chiral nematic phase changes of suspensions of poly(N,N-dimethylaminoethyl methacrylate)-grafted cellulose nanocrystals[J].Cellulose,2009,16(6):989-997.
[8] Onsager L.The effects of shape on the interaction of colloidal particles[J].Annals of the New York Academy of Sciences,1949,51(4):627-659.
[9] Qing Y,Sabo R,Zhu J Y,et al.A comparative study of cellulose nanofibrils disintegrated via multiple processing approaches[J].Carbohydrate Polymers,2013,97(1):226-234.
[10] Isogai A,Saito T,Fukuzumi H.TEMPO-oxidized cellulose nanofibers[J].Nanoscale,2011,3(1):71-85.
[11] Revol J F,Bradford H,Giasson J,et al.Helicoidal self-ordering of cellulose microfibrils in aqueous suspension[J].International Journal of Biological Macromolecules,1992,14(3):170-172.
[12] Majoinen J,Kontturi E,Ikkala O,et al.SEM imaging of chiral nematic films cast from cellulose nanocrystalsuspensions[J].Cellulose,2012,19(5):1599-1605.
[13] Kelly J A,Yu M,Hamad W Y,et al.Large,crack-free freestanding films with chiral nematicstructures[J].Advanced Optical Materials,2013,1(4):295-299.
[14] Giese M,Blusch L K,Khan M K,et al.Responsive Mesoporous pho-tonic cellulose films by supramolecularcotemplating[J].Angewandte Chemie International Edition,2014,53(34):8880-8884.
[15] Schlesinger M,Giese M,Blusch L K,et al.Chiral nematic cellulosegold nanoparticle composites from mesoporous photonic cellulose[J].Chemical Communications,2015,51(3):530-533.
[16] Rabani E,Reichman D R,Geissler P L,et al.Drying-mediated selfassembly of nanoparticles[J].Nature,2003,426(6964):271-274.
[17] Habibi Y,Lucia L A,Rojas O J.Cellulose nanocrystals:Chemistry,self-assembly,and applications[J].Chemical Reviews,2010,110(6):3479-3500.
[18] Moon R J,Martini A,Nairn J,et al.Cellulose nanomaterials review:Structure,properties and nanocomposites[J].Chemical Society Reviews,2011,40(7):3941-3994.
[19] Giese M,Blusch L K,Khan M K,et al.Functional materials from cel-lulose-derived liquid-crystal templates[J].Angewandte Chemie Inter-national Edition,2015,54(10):2888-2910.
[20] Wang N,Ding E,Cheng R.Surface modification of cellulose nanocrystals[J].Frontiers of Chemical Engineering in China,2007(3):228-232.
[21] Jung Y H,Chang T H,Zhang H,et al.High-performance green flexi-ble electronics based on biodegradable cellulose nanofibril paper[J].Nature Communications,2015,doi:10.1038/ncomms8170.
