【作者】 王崧；

【导师】 王文俊；

【作者基本信息】 浙江大学 ， 化学工程， 2018， 博士

【摘要】 超支化聚乙烯(HBPE)是含高度支化结构的聚乙烯,其分子结构近似球形、无链缠结,结晶度远低于常规聚乙烯,具有低玻璃化转变温度、低熔点、高溶解性和三维立体结构等特点。通过引入极性宫能团,可赋予HBPE新特性。由于合成HBPE的催化体系并不能适用所有官能团,因此高反应活性、强亲水性官能团的修饰仍具挑战。本论文提出了一种基于共聚和选择性后修饰策略,合成功能HBPE。通过高内相乳液(HIPE)制备的多孔聚合物(PolyHIPE)具有高孔隙率和完整的通孔结构,在催化、分离等领域应用广泛。由于制备过程中乳化剂用量大,使得其机械强度低,无法满足应用要求。本文利用高效HBPEPickering乳化剂制备PolyHIPE,通过降低乳化剂用量,极大地提高了机械强度,可作为热二极管中相转变材料的框架。研究内容分为以下三个部分:(1)通过一步共聚法引入环氧基团,合成反应型两亲性HBPE,并用于酶在有机溶剂中的催化。首次利用两相法制备了 HBPE-酶纳米复合物,有效地提高了酶在有机溶剂中的催化活性,并具有良好的常温储存稳定性和回收再利用能力。(2)通过共聚和后修饰的合成方法制备含磺酸钠的HBPE Pickering乳化剂,兼具小分子表面活性剂和Pickering乳化剂的优点,高效稳定HIPE。并通过降低聚合物骨架中乳化剂的残留,提高PolyHIPE的机械强度,首次制备得到杨氏模量达到理论最大值的PolyHIPE。(3)以PolyHIPE为骨架与相转变材料相复合,得到热导率在相转变温度上下呈突越式变化的全固态复合物,解决了低工作温度差、全固态热二极管的选材和制备难题。并以此复合物为基础,制备了单相转变和双相转变两代热二极管,在低工作温度差下得到的热整流比高于文献报道值。更多还原

【Abstract】 Hyperbranched Polyethylene(HBPE)contains highly branched chains,whose molecular structure is spherical and without chain entanglements.Its crystallinity is far lower than industry polyethylene,having low glass transition temperature,low melting pointing,and 3D structure.Furthermore,HBPE can be easily modified by copolymerization.So far,because catalytic systems of HBPE are sensitive to the functional groups,modification with highly reactive and amphiphilic groups is a long-term challenge.In this thesis,a universal strategy for the functionalization of HBPE via a combination of copolymerization and post modification is developed.Porous polymers(PolyHIPEs)made from high internal phase emulsion(HIPE)have high porosity and fine interconnected pore structures,widely used in many applications such as catalysis and separation.Poor mechanical property due to large surfactant dosage during fabrication can’t meet the requirement of further application.This thesis dramatically increases the mechanical strength through minimizing surfactant dosage by high efficient HBPE Pickering emulsifier,Thermal diodes are made from PolyHIPEs as skeleton of phase change materials.Corresponding contents are divided into three parts:(1)Reactive amphiphilic HBPEs with epoxy groups made by one step copolymerization are used in enzymatic catalysis in organic solvent.Bi-phase system is firstly introduced for synthesizing HBPE-enzyme nanocomposite,which can improve enzymatic activities in organic solvent with good stability in ambient temperature and recycle ability.(2)HBPE Pickering surfactants synthesized by copolymerization and post modification have the advantages of both surfactant and Pickering emulsifier,can stabilize HIPE.Enhanced mechanical strength is obtained by decreasing surfactant residual in skeletal polymer,for the first time,reaching the theoretical maximum value of PolyHIPE.(3)Composite of skeletal PolyHIPE impregnated with phase change materials has a large step of thermal conductivity as it crosses the phase transition temperature,can maintain its shape and solid-state nature during through the entire range of working temperatures.Two generations of phase change thermal diode are made based on the composite with highest thermal rectification in literature.更多还原