具有自由基猝灭功能单分子膨胀型阻燃剂修饰层状纳米磷酸锆及其协同阻燃聚烯烃的研究

High efficiently halogen-free flame retardant polyolefin is one of the most important development directions of high performance polyolefin (PO). In order to solve the low efficiency defect of the existing intumescent flame retardant, firstly, a novel single-molecule intumescent flame retardant possessing free-radical quenching capability (QSIFR) is synthesized by N-alkoxy hindered amine, cyanuric chloride and other reagents via nucleophilic substitution. Secondly, the exfoliated zirconium phosphate nanosheets (ZrP) with different sizes are prepared through the hydrothermal method and exfoliation modification. Subsequently, QSIFR-ZrP possessing catalyzing carbonization and free-radical quenching capability is prepared by using QSIFR to chemically decorate ZrP. Afterward, high performance halogen-free flame retardant PO/QSIFR-ZrP nanocomposites are prepared via melting blend. This proposal makes good use of solid acid catalyzing carbonization and layer barrier effect of α-ZrP, as well as the peculiar intramolecular charring and free-radical quenching mechanism of QSIFR, to realize the high flame-retardant efficiency of QSIFR-ZrP. In addition, the free-radical quenching and multiple catalyzing carbonization mechanisms of QSIFR-ZrP on PO are systematically studied and clarified, and the synergistic flame-retardant mechanism between ZrP and SIFR is further revealed, which is beneficial to develop and break through the existing halogen-free flame retardant technology and theory. Through this research, the new ideas and theoretical basis should be provided for the design, preparation and application of the high performance halogen-free flame retardant polymer.

高效无卤阻燃是聚烯烃（PO）高性能化的重要发展方向。为解决现有膨胀型阻燃剂效率偏低的缺陷，本项目采用N-烷氧基受阻胺和三聚氯氰等经亲核取代反应，合成具有自由基猝灭功能的单分子膨胀型阻燃剂（QSIFR）；随后通过水热法和剥离改性制备不同尺寸的剥离型层状纳米磷酸锆（ZrP）；采用QSIFR对ZrP进行化学修饰，合成兼具高效催化成炭和自由基猝灭功能的QSIFR-ZrP；将其与PO熔融共混制备高效无卤阻燃PO纳米复合材料。巧妙利用ZrP的固体酸催化成炭效应和片层阻隔作用，以及QSIFR特有的分子内成炭和自由基猝灭机制，将催化成炭和自由基猝灭作用有机耦合，实现PO的高效阻燃。在此基础上，深入研究并阐明QSIFR-ZrP对PO的自由基猝灭作用及多层次催化成炭机制，揭示QSIFR和ZrP协同阻燃PO的作用机理，对现有无卤阻燃技术和理论进行创新，为高效无卤阻燃聚合物的设计、制备及应用提供新方法和理论依据。

如何实现催化成炭与自由基猝灭作用的高效耦合，是当前高性能无卤阻燃聚烯烃发展与应用亟需解决的关键问题。本项目采用N-烷氧基受阻胺、三聚氯氰和六氯三聚磷腈等经亲核取代反应，合成了具有自由基猝灭功能的膨胀型阻燃剂（QIFR）；采用QIFR对磷酸锆（ZrP）纳米片进行修饰，制备了一系列兼具高效催化成炭与自由基猝灭功能的膨胀型阻燃剂（QIFR-ZrP），随后将其与聚丙烯（PP）熔融共混，制备了兼具优良阻燃性能、热稳定性能和力学性能的无卤阻燃PP。仅添加20wt%的阻燃剂，阻燃PP的极限氧指数即可达到34.0%，并通过UL94 V-0级；同时阻燃PP的热释放速率峰值、总热释放量和烟释放量等也大幅下降。本项目系统研究了QIFR-ZrP的结构及用量对PP阻燃性能的影响；深入探讨了ZrP、QIFR和QIFR-ZrP等对PP气相裂解产物及燃烧后炭层结构和形貌的影响规律，阐明了微纳限域空间内QIFR-ZrP对PP的多层次催化成炭作用机制，揭示了QIFR和ZrP协同阻燃PP的作用机理。受热燃烧时，QIFR-ZrP分解产生氮氧自由基，有效抑制了PP的降解和燃烧，而ZrP纳米片催化其表面的QIFR快速成炭，形成封闭的微纳限域空间，使氮氧自由基可以更高效地捕捉PP分解生成的大分子自由基；同时ZrP纳米片发挥固体酸催化和片层阻隔作用，在基体表面生成完整、致密的膨胀炭层，有效阻隔氧气、可燃气体和热量的传输，从而实现PP的高效无卤阻燃。本项目为高效无卤阻燃聚合物的设计、制备及应用提供了新方法和理论依据，具有重要的科学意义与应用价值。在项目执行过程中，项目组成员在Chemical Engineering Journal, ACS Applied Materials & Interfaces, Journal of Hazardous Materials, Composites Part B和Composites Part A等本领域高水平学术期刊上发表学术论文27篇（其中SCI收录26篇，EI收录1篇），申请中国发明专利8件（已获授权7件），获得广东省科技进步二等奖1项，参加全国重要学术会议4次，培养博士生4名（已毕业3名）、硕士生6名（已毕业4名）。