各向异性纳米纤维素基水凝胶的制备及应用进展

Progress in preparation and application of anisotropic cellulose-based hydrogels

纳米纤维素是天然一维纳米材料,具有高长径比、机械性能优良、独特的双折射效应等性质。基于纳米纤维素开发制备的各向异性水凝胶材料,表现出与皮肤、肌肉和软骨等天然组织相似的力学、光学、传质等性质的各向异性,在仿生工程、生物医学工程等领域具有优异的应用前景。围绕如何有效地利用纳米纤维素的自身结构特点开发高强度、功能性纳米纤维素基水凝胶,从制备方法、性质特征和应用3个角度,综述了近年来各向异性纳米纤维素基水凝胶的研究进展:系统总结了各向异性纳米纤维素基水凝胶材料自下而上和自上而下2种制备方法;重点阐述了其极高的力学强度、独特的双折射性质、可控的传质途径、各向异性导电、各向异性导热等优异特性;详细介绍了其在机械、显示、传感与生物医学等领域的应用情况。最后,根据各向异性纳米纤维素基水凝胶的研究进展,提出其探索低成本、简便的新型制备方法,提升其多功能性与构建其可预测的本构模型仍是各向异性纳米纤维素基水凝胶未来研究的重点。

Nanocellulose-based hydrogels are a hot topic in biomimetic materials,biomedical engineering and tissue engineering due to their advantages of reproducibility,good biocompatibility and excellent mechanical properties.The structure of nanocellulose is one of the important factors affecting the properties of hydrogels.Due to its high aspect ratio,excellent mechanical properties and unique birefringence effect,nanocellulose has attracted wide attention in the preparation of anisotropic hydrogels.Based on its structural characteristics,nanocellulose is very suitable as the orientation frame of anisotropic hydrogels,which can effectively improve the mechanical,mass transfer and optical properties of hydrogels in specific directions.The composite gel has very high mechanical strength in orientation and exhibits unique birefringence properties.In terms of mass transfer,the composite gel has a controllable mass transfer pathway.All this has led to the development of biomimetic materials that mimic natural skin,muscle and cartilage.However,to develop high strength and specific functional nanocellulose based hydrogels,effective utilization of the structure and physical and chemical properties of nanocellulose is still an urgent problem to be solved.In recent years,many scholars have focused on the construction of anisotropic nanocellulo-based hydrogels with directional structure,so as to expand their application fields.In order to effectively utilize the structure characteristics of nanocellulose and prepare high-strength and multi-functional nanocellulose-based hydrogels,this study reviews the research progress of anisotropic nanocellulose-based hydrogels in recent years from the perspectives of preparation methods,properties and application fields.Firstly,the bottom-up and top-down preparation methods of anisotropic nanocellulose-based hydrogels were systematically summarized.Among them,the common bottom-up method includes the force induced orientation method,shear flow orientation method,electromagnetic orientation method,ice template orientation method,etc.,while the top-down method mostly uses the natural cellulose skeleton orientation method.Secondly,the excellent properties of anisotropic nanocellulose-based hydrogels,such as extremely high mechanical strength,unique birefringence optical properties,controllable mass transfer pathway,anisotropic conductivity and anisotropic thermal conductivity,are described.In addition,the applications of anisotropic nanocellulose-based hydrogels in the fields of machinery,display,sensing and biomedicine are introduced in detail.Finally,according to the research progress of anisotropic nanocellulose-based hydrogels and combined with its own scientific research practice,this study proposes that the future research directions of anisotropic nanocellulose-based hydrogels are to explore low-cost and simple new preparation methods,improve its versatility and develop its predictable constitutive models for fabricating anisotropic cellulose-based hydrogels.