纳米纤维素
自愈水凝胶
纤维素
材料科学
化学工程
粒子(生态学)
各向异性
双折射
纳米颗粒
衍射
纳米技术
复合材料
高分子化学
光学
地质学
工程类
物理
海洋学
作者
Pierre Munier,Korneliya Gordeyeva,Lennart Bergström,Andreas Fall
出处
期刊:Biomacromolecules
[American Chemical Society]
日期:2016-04-26
卷期号:17 (5): 1875-1881
被引量:148
标识
DOI:10.1021/acs.biomac.6b00304
摘要
We show that unidirectional freezing of nanocellulose dispersions produces cellular foams with high alignment of the rod-like nanoparticles in the freezing direction. Quantification of the alignment in the long direction of the tubular pores with X-ray diffraction shows high orientation of cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) at particle concentrations above 0.2 wt % (CNC) and 0.08 wt % (CNF). Aggregation of CNF by pH decrease or addition of salt significantly reduces the particle orientation; in contrast, exceeding the concentration where particles gel by mobility constraints had a relatively small effect on the orientation. The dense nanocellulose network formed by directional freezing was sufficiently strong to resist melting. The formed hydrogels were birefringent and displayed anisotropic laser diffraction patterns, suggesting preserved nanocellulose alignment and cellular structure. Nondirectional freezing of the hydrogels followed by sublimation generates foams with a pore structure and nanocellulose alignment resembling the structure of the initial directional freezing.
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