有机长链离子修饰无机纳米粒子及调控聚合物复合材料结构和性能研究

It is easy to cause the high viscosity, poor interfacial compatibility and is difficult to eliminate the particles aggregate in the process of melt blending or melt spinning of polymer composites filled with inorganic nanoparticle. These unfavorable factors exist extensively in the field of polymer processing, restricting comprehensive performance of composites and nanoparticles functionality. However, solvent-free core-shell nanoparticles with low viscosity and controllable structure is introduced into polymer to simultaneously solve the above problems. A series of monodisperse solvent-free core-shell nanoSiO2 fluids with controllable rheological properties and grafting state are prepared by acid-base reaction one step; Effect of graft factors (grafting density, grafting length and molecular types) on viscoelastic behavior of solvent-free nanofluids are systematically investigated, revealing the key factors of achieving solid SiO2 nanoparticle dispersion and flow behavior; Structure stability and rheological behavior of polymer composites filled with solvent-free particles are investigated in the melting shear process, and the combination of online/intermittent observing the dispersion mechanism of monodisperse solvent-free particles with different grafting state in the polymer matrix and interaction of particle-particle and particle/polymer chain, to construct the method and theory of structure and performance regulating of composite material based on solvent-free fluids microstructure. Research results can provide theoretical basis and technical support of inorganic particles masterbatch designs used for melt blending or melt spinning, and the production of high dispersion fiber composites.

无机纳米粒子/高分子复合材料在熔融共混或熔融纺丝过程中，容易造成粘度高，界面相容性差，而且很难消除粒子团聚体，这些不利因素在聚合物加工领域中严重制约复合材料综合性能和纳米粒子功效发挥，而低粘度、结构可控无溶剂型核壳纳米粒子引入聚合物将同时解决以上问题。本项目拟通过酸碱反应一步法制备一系列流变性能和接枝状态可单一调控的单分散核壳纳米SiO2类流体；系统研究接枝状态各因素(接枝率、接枝长度和分子类型等)对纳米类流体粘弹行为影响，揭示决定固体SiO2纳米粒子分散及其具有流动行为关键因素；考察剪切过程中粒子结构稳定性和流变行为，并结合在线/间歇观察不同接枝状态的单分散纳米类流体在聚合物中的分散机制及粒子-粒子和接枝链/基体分子链相互作用，构建针对纳米类流体微观结构调控复合材料的结构与性能方法和理论。研究成果可为熔融共混或复合纺丝的无机粒子母料设计和高分散性复合纤维的生产提供理论依据和技术支撑。

本项目拟针对无机纳米粒子/高分子复合材料制备过程中粘度高、粒子团聚等技术问题。采用离子交换法制备了一系列单分散的核壳SiO2纳米流体，研究流变行为，发现通过改变壳层厚度(2.3～7.3 nm)能显著调控流体的粘度和模量；此外流体熔融温度与壳层分子链的长度有关，表明壳层长链离子自身熔融温度高低对调控纳米流体流动行为起到关键作用。同时通过对埃落石(HNTs)进行表明羟基化处理，首次合成了HNTs流体并用于制备HNTs/聚苯乙烯复合材料，发现仅仅0.39 wt% HNTs填充量，其力学性能达到最高，而且在填料临界阈值(0.45 wt%)左右，热导率急剧上升，这与纳米流体在聚合物基体中高度分散及表面有机长链离子相容性较好有关。而且，在项目的进行过程中，申请人探索了采用基于氢键相互作用方法制备炭黑流体、SiO2/氧化石墨烯杂化流体，该方法过程简单，环保。其原理利用PEO-b-PPO-b-PEO嵌段共聚物与粒子表面羟基相互作用形成氢键，降低了嵌段共聚物结晶温度，在40-60oC范围内出现固-液转变点。该方法不需要对粒子表面进行化学处理，适用于一系列无机纳米粒子表面物理改性，具有重要的学术和工业应用价值。项目执行期内，共发表标注基金资助的论文12篇。