POSS嵌段共聚物改性环氧树脂

Epoxy Composites Modified with POSS-Containing Block Copolymer

采用可逆加成-断裂转移聚合(RAFT)方法合成甲基丙烯酰氧丙基七异丁基笼形倍半硅氧烷(MAiBuPOSS)和9,10-二氢-9-氧杂-10-磷杂菲-10-氧化物甲基丙烯酸乙酯(HEPO)的嵌段共聚物PMAiBuPOSS-b-PHEPO(BCP),用于改性双酚A型环氧树脂。利用扫描电镜表征环氧树脂复合材料的断面形貌,发现PMAiBuPOSS-b-PHEPO嵌段共聚物可在环氧树脂中发生自组装,形成了以POSS嵌段为核、含磷嵌段为壳的核壳结构自组装体。动态力学分析、热重分析、差示扫描量热分析、垂直燃烧测试(UL-94)及极限氧指数(LOI)研究表明,PMAiBuPOSS-b-PHEPO嵌段共聚物中PHEPO链段增强了聚合物与环氧树脂的相容性,PMAiBuPOSS链段显著提高了环氧树脂的热稳定性和阻燃性能。当PMAiBuPOSS-b-PHEPO质量分数为5%时,环氧树脂复合材料LOI值为33.0%,UL-94燃烧等级为V-0级,且其力学性能也得到显著提升。

A block copolymer named PMAiBuPOSS-b-PHEPO was synthesized via reversible additionfragmentation transfer polymerization （RAFT） and blended by using methaerylolsobutyl polyhedral oligomeric silsesquioxane （MAiBuPOSS） and 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide ethyl methacrylate（HEPO） as monomers. This polymer was adopted to modify bisphenol A-based epoxy resin. Scanning electron microscope （SEM） characterization of the fracture surface of the composites indicates that PMAiBuPOSS-b-PHEPO could self- assemble in the epoxy resin to form a structure with POSS enriched core and PHEPO enriched shell. The thermal, mechanical and flame-retardant properties of the composites were characterized by dynamic mechanical analysis （DMA）, thermogravimetrie analysis （TGA）, differential scanning calorimetry （DSC）, vertical combustion test （UL-94） and limiting oxygen index measurement （LOI）. It is found that PHEPO could improve the compatibility between PMAiBuPOSS-b-PHEPO and epoxy resin, therefore evidently improving the thermal stability and flameretardance of the composite materials. With a mass fraction 5% of PMAiBuPOSS-b-PHEPO, the as formed composite materials possess a LOI value of 33.0%, reach UL-94 V-0 rating, as well as exhibit an enhanced mechanical strength.