气相二氧化硅填充极性低聚物的界面与流变

气相二氧化硅(FS)/低聚物纳米复合材料应用广泛于涂料、胶黏剂、锂离子电池、液体防弹衣等诸多领域.然而,极性低聚物与FS表面相互作用复杂,FS/低聚物复合材料(ONCs)的流变响应多种多样.如何实现ONCs流变行为调控,是长期困扰工业界的难题.本文详细总结了FS在ONCs领域的应用,将FS粒子间相互作用与ONCs流变性质相关联,综述ONCs界面层结构的表征、调控手段及界面层与流变行为的关系.结合本课题组对FS/极性低聚物体系界面及流变行为的研究成果,提出未来ONCs领域的2个重要方向,即研究界面结构与粒子-极性低聚物相互作用间的关系,并通过界面设计实现对纳米粒子/极性低聚物复合材料的流变行为的精确调控.

Interfacial Structure and Rheology of Fumed Silica Filled Polar Oligomer Nanocomposites

Fumed silica (FS) has become irreplaceable for a wide range of applications such as adhesives,coatings,lithium battery,and liquid armor,etc.,especially when serving as the rheological agent.However,it is a great challenge to control the rheological behavior of polar liquids like reactive polar oligomers when employing FS,because complicated interactions between the surfaces of FS and polar molecules could make it difficult for formula design and rheological performance adjustment of industrial products.In this work,synthesis and classification of typical FS are introduced,followed by representative applications of FS as rheological agents in the field of oligomer nanocomposites (ONCs).Then four interactions between nanoparticles:van der Waals attraction,electrostatic repulsive force,steric repulsive force and hydrogen bonding attraction that are crucial to rheological behaviors of ONCs are elaborated in detail.Meanwhile,the rheological behaviors of both dilute and concentrated ONCs,particularly the FS/polar oligomer nanocomposites,are summarized,and the rheological responses of dense dispersions are concluded into two categories:(i) flocculated system and (ii) non-flocculated system.Both flocculated and non-flocculated behaviors are related to particle-oligomer and particle-particle interactions,and their typical rheological responses including thixotropy and shear thickening,as well as their influencing factors are also stated and compared.Furthermore,researches in interfacial layer structures between nanoparticles and ONCs are thoroughly overviewed on the basis of a summary on the measurement and control of interfacial layer structures,and the relationship between rheological behavior and interfacial structures of ONCs (FS filled systems in particular) are comprehensively expounded.Combined with the recent progress in FS filled polar oligomers about rheology and interface,two important research directions are proposed for ONCs at last:one is how to establish direct relationships between the interfacial layer structure and the interactions for nanoparticles and polar oligomers,and the other is how to precisely regulate and control the rheology of FS/oligomer nanocomposites by elaborate design of interfacial structures.