一种新型含硅氧烷间隔基元的半芳香族共聚酰胺

Semi-aromatic Polyamides Containing Siloxane Unit toward High Performance

通过芳香族亲核取代反应合成了一系列含硅氧烷基元主链结构的半芳香族共聚酰胺.研究发现,共聚酰胺具有较高的分子量和较窄的分子量分布.硅氧烷结构的引入不仅赋予了共聚酰胺低的吸水率,而且使其能保持良好的力学性能,当硅氧烷结构含量为10 mol%时,拉伸强度达到80.0 MPa,缺口冲击强度为4.8 kJ/m^2,可与商品化HTN产品相媲美.阻燃性能测试结果可知,在不添加磷、卤等传统阻燃剂的情况下,随着硅氧烷结构含量的增加,共聚酰胺表现出良好的阻燃抗熔滴效果.当共聚酰胺中硅氧烷结构含量为10 mol%时,极限氧指数可达33.5%,可通过UL-94垂直燃烧V-0级.

Semi-aromatic polyamides(SaPAs)and their derivatives combining each advantage of aromatic and aliphatic polyamides receive ever-increasing interest in both academic and industrial fields.However,severe challenges,such as processibility and flammability of SaPAs still remain which limit their versatile applications.In order to endow satistied processibility of SaPAs either in melt or in solution,tremendous efforts have been explored to weaken the interchain cohesive energy by chemical modification of the SaPAs’backbones or side groups.Unfortunately,their flame retardancy got even worse.In this work,a novel series of SaPAs containing flexible siloxane spacers and rigid fluorenyl pendent,termed P-FPH100−xSix,were designed and synthesized through the aromatic nucleophilic substitution(SNAr)polycondensation.The effects of both the fluorenyl pendent and siloxane spacers on the comprehensive properties of the semi-aromatic polyamides were comprehensively investigated.On the one hand,the presence of the rigid fluorenyl pendent endowed the resulting P-FPH100−xSix with enhanced thermal stability and mechanical properties,compared with the commercially available HTN.On the other hand,with increasing content of the siloxane spacers,their tensile strength and impact strength gradually decreased.Most importantly,by introducing the silaxane spacers,P-FPH100−xSix displayed intrinsic flame retardancy and anti-dripping performance despite the absence of conventional P-/N-containing flame retardants.When the content of the siloxane spacers was 10 mol%,the P-FPH80Si20 did not only achieve the V-0 rating in UL-94 burning test with limiting oxygen index(LOI)as high as 33.5%,but also maintain 80.0 MPa of tensile strength and 4.8 kJ/m^2 of the notched Izod impact strength.Taking the aforementioned advantages,this kind of novel SaPAs hold potential in a wide range of applications.