文献类型：期刊文献

英文题名：Dual-Enhanced Hydrophobic and Mechanical Properties of Long-Range 3D Anisotropic Binary-Composite Nanocellulose Foams via Bidirectional Gradient Freezing

作者：Chen, Yuan[1,2] Yang, Sheng[1] Fan, Dongbin[1] Li, Gaiyun[1,2] Wang, Siqun[1,3]

第一作者：陈媛

通信作者：Li, GY[1];Li, GY[2]

机构：[1]Chinese Acad Forestry, Res Inst Wood Ind, 1 Dongxiaofu Xiangshan Rd, Beijing 100091, Peoples R China;[2]Chinese Acad Forestry, Res Inst Wood Ind, Hunan Collaborat Innovat Ctr Effect Utilizing Woo, 1 Dongxiaofu Xiangshan Rd, Beijing 100091, Peoples R China;[3]Univ Tennessee, Ctr Renewable Carbon, Knoxville, TN 37996 USA

年份：2019

卷号：7

期号：15

起止页码：12878-12886

外文期刊名：ACS SUSTAINABLE CHEMISTRY & ENGINEERING

收录：;EI(收录号：20193407342021);Scopus(收录号：2-s2.0-85070911573);WOS:【SCI-EXPANDED(收录号:WOS:000480370500027)】；

基金：We gratefully acknowledge support from National Nonprofit Institute Research Grant of Chinese Academy of Forestry (CAFYBB2017ZX003) and the National Natural Science Foundation of China (31700480). Moreover, we thank Xu Xiuping from Plant Science Facility of the Institute of Botany, Chinese Academy of Sciences, for excellent technical assistance on the micro-CT imaging system.

语种：英文

外文关键词：elasticity-enhanced; bidirectional gradient freezing; 3D anisotropic nanocellulose foam; silylated modification

摘要：Inspired by the structured architecture of natural materials, research has focused on the assembly of long-range three-dimensional (3D) anisotropic aligned structure through the synergy of silylated binary-composite and bidirectional gradient freezing using renewable and biocompatible cellulose nanofibrils. Low-cost methyltrimethoxysilane (MTMS) was introduced to reinforce the cross-linking strength between nanofibrils, simultaneously improving the surface hydrophobicity of cellulose foams. A copper coldfinger with a thermal insulative polydimethylsiloxane (PDMS) wedge was used to build bidirectional anisotropic aligned porous structures using bitemperature gradients to control the nucleation and propagation of ice crystals. This two-step method successfully assembled the cellulose nanofibrils into ultralight and ultraporous foams. The effects of freezing techniques, including freezer freezing, unidirectional gradient freezing, and bidirectional gradient freezing on the internal morphology and surface structure of modified foams have been thoroughly investigated by micro-CT and SEM characterizations. The developed 3D anisotropic honeycomb-like foams exhibited excellent compressive elasticity and enhanced ultraporous properties. Moreover, the synergistic effect of chemical techniques and freezing methods has realized a dual enhancement of the surface hydrophobicity and mechanical properties of cellulose foams. Our methodology could provide an effective way of achieving precise control of the final architecture of high-aspect-ratio fibril materials. Moreover, it offers a flexible process for preparing various functional composites: in particular, advanced materials such as for energy storage, thermal insulation, and composites requiring a higher level of structure control.