超支化聚苯并噁嗪的分子设计及其对聚苯并噁嗪树脂的增韧和阻燃机理研究

On account of many excellent properties and drawbacks of benzoxazine resin and hyperbranched polymer, the synthetic idea of novel hyperbranched polybenzoxazines based on benzoxazine as skeleton via Mannich condensation reaction is firstly presented through molecular designing in this project. The influence rules of the structure of reactants and process conditions on the degree of branching, molecular weight, and distribution of molecular weight of hyperbranched polybenzoxazines are systematically investigated. The controllable preparation methods of hyperbranched polybenzoxazines are established. The properties of typical benzoxazine monomers are greatly modified by blending with hyperbranched polybenzoxazines. The effect mechanisms of the structure of hyperbranched polybenzoxazines on the mechanical properties, thermal properties, and flame retardant properties of copolymers are interpreted. Consequentially, the internal relationship between the structure of hyperbranched polybenzoxazines and the properties of copolymers will be confirmed. The toughening mechanism and flame-retardant mechanism of hyperbranched polybenzoxazines to benzoxazine resins will be revealed. By means of regulation and control of end groups, degree of branching, molecular weight, rigid and flexible groups, and introduction of boron and silicone in hyperbranched polybenzoxazines, the compatibility between hyperbranched polybenzoxazines and matrix resins is improved. The curing temperature of benzoxazine resin is decreased. The thermal properties, toughness and flame retardant property of copolymers are greatly enhanced. Therefore, this project can provide scientific basis for the preparation of hyperbranched polybenzoxazines and the application in the advanced resin matrix composites, flame resistant materials, etc., and promote the development and improvement of theory and application research for the related discipline and industry.

本课题基于苯并噁嗪树脂和超支化聚合物所具有的优异性能和存在的不足，通过分子结构设计，经Mannich缩合反应，首次提出以苯并噁嗪为骨架的新型超支化聚苯并噁嗪合成思想，系统研究反应物结构和工艺条件对超支化聚苯并噁嗪支化度、分子量及其分布的影响规律，建立超支化聚苯并噁嗪的可控制备方法；以超支化聚苯并噁嗪对苯并噁嗪树脂进行共混改性，阐释超支化聚苯并噁嗪结构对共聚物力学、热、阻燃等性能的影响机制，明确超支化聚苯并噁嗪结构与共聚物性能之间的内在联系，揭示超支化聚苯并噁嗪的增韧和阻燃机理；通过调控超支化聚苯并噁嗪封端基团、支化度、分子量、刚性和柔性基团及引入硼硅元素，改善超支化聚合物与苯并噁嗪树脂的相容性，降低固化温度，提高聚苯并噁嗪树脂的热性能、韧性和阻燃性能，为超支化聚苯并噁嗪的制备及在先进树脂基复合材料、阻燃材料等领域的应用提供科学依据，促进相关学科和行业理论与应用研究的发展和完善。

热固性树脂具有高刚性、高硬度、耐高温、不燃性、尺寸稳定性好等优点，在航空航天、电子、交通运输等领域得到广泛应用。但高性能热固性树脂通常存在固化温度高，加工性能差，脆性大，难以制成薄膜等缺点。.本项目通过分子结构设计，开发了兼具良好热性能、力学性能、阻燃性能的新型超支化苯并噁嗪新产品。该类产品制备工艺条件温，原料来源广泛。通过调控超支化苯并噁嗪的分子量、末端基团、刚性和柔性基团以及引入硼、硅元素，从而改善树脂的加工性能、韧性、阻燃、介电等性能。.所研制的超支化苯并噁嗪在常规溶剂中具有良好的溶解性，很容易制成柔性薄膜。其中，苯并噁嗪封端的AB2型超支化聚合物在高频范围内表现出极低的介电常数（2-18GHz的k值为2.13-2.18）及损耗（0.0010-0.0232），在电子封装等领域有着潜在的应用价值。含硅超支化苯并噁嗪热释放速率峰值（pHRR）温度为415-453 ℃之间，总热释放量（THR）在15.22-19.15 kJ/g之间，热释放能力（HRC）在49.87-81.94 J/(g K)之间，材料具备不可燃属性，呈现优异的阻燃性能。全芳香性和全生物基超支化苯并噁嗪具有高的玻璃化转变温度（320℃以上）和热稳定性（T5、T10和Yc值分别高达368-374、388-415 ℃和49.1-63.2%）以及优异的阻燃性能（THR和HRC值分别为5.4-7.4 kJ/g和39.6-41.5 J/(g k)），达到不燃物的标准，表明其有作为阻燃材料的潜力。此外，全生物基超支化苯并噁嗪有极低的热膨胀系数（仅为8.4 ppm/℃），显示出优良的尺寸稳定性。.超支化苯并噁嗪与苯并噁嗪、环氧、氰酸酯、邻苯二甲腈等热固性树脂具有良好的兼容性，可与其发生共聚，无相分离现象。此外，超支化苯并噁嗪具有较低的熔点，其端基活性羟基或氨基可促进热固性树脂在低温下发生交联反应，极大地降低了树脂的固化温度，共聚物的交联密度提高，热性能未见明显下降，而力学性能（包括拉伸、弯曲和抗冲击性能）显著提高，脆性得到极大改善。同时，其固有的高阻燃性能、低介电性能、尺寸稳定性等可促进热固性树脂的综合性能的提高，在热固性树脂改性领域有广泛的应用前景。