基于磷腈环的枝化苯并噁嗪单体的分子设计与聚合物性能

Benzoxazine resins are developed class of high-performance thermosetting resins instead of traditional phenolic-formaldehyde resin in high-tech field. These thermosetting resins not only possess all the advantages of traditional phenolic resins such as excellent mechanical and thermal properties, dimentional stability and high chemical resistivity, but also have unique advantages of near-zero shrinkage upon curing, higher thermal stability and flame retardant, low water absorption ,self-catalyzed curing without additional acid catalyst,and remarkable molecular design ?exibility. Besides, corresponding monomers can be conveniently designed and generated, so the functional polybenzoxazines can be easily gained and satisfied for different applications. The major defects that limit the wide application of common polybenzoxazine resins in high-tech field are difficulty in processing and poor mechanical strength (low toughness), high polymerization temperature, and low-level flame retardant and thermal stability.One of the solution for solving those shortcomings is to design new type monomer with special structure.In this project we propose to prepare a novel branched benzoxazine monomer based on phosphazene ring. Combining the chemical flexibility of hexachlorocyclophosphazne and high thermal stability of phosphazen ring, we can obtained high-performance benzoxazine resin with satisfied toughness.Systematic studying the curing characters of monomer and properties of cured resin, we hope to understand structure/property relationship of the newly designed polybenzoxazine.By the aid of reactivity of benzoxazine ring, aryl phosphonate will be introduced into benzoxazine structure by chemical bond in order to obtain internal plasticized polybenzoxazine resin and lower the polymerization temperature of monomer.

苯并噁嗪树脂是一类新型的高性能高分子材料，结构类似于传统的酚醛树脂。它不仅具有酚醛树脂优异的机械性能、高化学稳定性、尺寸稳定性，绝缘性能、热稳定性，并且独具特色：单体热固化过程近零收缩率、固化后的样品吸水率低、阻燃性高、自催化固化而不需要酸催化剂、单体制备工艺简单，易于工业化。阻碍苯并噁嗪树脂在高技术领域广泛使用的主要缺陷是性脆、固化温度高、耐热性和阻燃性尚需进一步提高。设计合成新型单体，是解决上述缺陷的途径之一。本项目提出设计合成基于磷腈环的枝化苯并噁嗪新型单体，利用六氯环三磷腈的可修饰性和磷腈环的高稳定性，制备兼具高热稳定性和高韧性的含磷苯并噁嗪树脂，通过研究单体的固化行为和聚合物性能，力求阐明枝化苯并噁嗪的结构-性能的关系；同时利用苯并噁嗪环的可反应性，在分子内通过化学键引入热稳定性的芳基磷酸酯基团，利用芳基磷酸酯高效增塑的作用，探索苯并噁嗪树脂的新型增韧方法和降低聚合温度的新途径。

通过优化分子结构，阐明聚苯并噁嗪结构与性能的内在关系，是目前研究前沿之一。研究基于环三磷腈核的枝化苯并噁嗪树脂结构与性能的关系，发现含席夫碱结构的六官能度苯并噁嗪单体熔点为98.2℃，聚合起始温度为194.1℃。聚苯并噁嗪表现出良好的热稳定性和机械性能，失重5%时温度为348.0℃， 850℃残碳率为56.5%，室温储能模量为2.55 GPa，Tg为189.6℃。将苯并噁嗪单元提高到十二个，所获得枝化苯并噁嗪单体的熔点为114.2℃，而聚合起始温度为206.2℃，显示较宽的操作窗口；同时聚合物5%热失重温度为394.6℃，850℃残碳率为51.3%，室温储能模量为2.86 GPa，Tg值为203.9℃。采用枝化多元酚制备苯并噁嗪树脂，可以有效控制苯并噁嗪单元的含量，且残留酚的催化作用使聚合温度降低。.将三氟甲基引入苯并噁嗪结构，在保持枝化苯并噁嗪单体具有较高分子量（960-1493g/mol）的同时，可以进一步降低单体的熔点，其中间-三氟甲基取代的苯并噁嗪树脂，在常温下为粘流态，最高熔点为82℃，而所有含氟单体的起始聚合温度均大于210℃,具有较宽的加工温度。含氟聚苯并噁嗪玻璃化温度最高可到210℃,室温储能模量达到9.0 GPa，850℃残炭率超过60%。同时部分枝化单体表现出膨胀聚合的特征，基于密度变化的膨胀率最高可达4%以上。单体聚合表观活化能在90-123 KJ/mol之间。提出“噁嗪值”的概念，以定性关联单体结构中噁嗪环含量与聚合物交联密度等基本物理性能。枝化聚苯并噁嗪的介电常数较高在3.0-5.9之间，介电损耗较低在0.0049-0.0183之间。利用苯并噁嗪的反应性，以枝化苯并噁嗪和天然腰果酚为原料，采用无溶剂法制备了枝化结构的“合成生漆”，涂膜性能与天然生漆相当，阻燃性能远优于天然生漆（LOI为30%）。.利用磷化氢（磷化工尾气）衍生物制备了新型含磷聚苯并噁嗪，聚合物在850℃下的残炭率达到47.4%，为磷化氢尾气的高效利用和循环利用提供了新的途径。利用对-乙烯基苯胺为原料制备了双官能团乙烯基苯并噁嗪，采用双键的自由基聚合获得高分子量线形聚乙烯基苯并噁嗪，聚合物在200℃以下可以热塑加工，而受热（>220℃）发生开环聚合获得热固性材料；锥形量热仪测试证明该聚合物具有优异的阻燃性能，为聚苯并噁嗪的高性能化提供了新途径。