表面改性纳米TiO_2粒子杂化PI薄膜的制备与性能研究

Preparation and properties investigations of hybrid films of polyimide(PI) doped with surface modified nano-TiO2 particles

采用硅烷偶联剂(γ-巯丙基三乙氧基硅烷)对纳米TiO2粒子进行表面处理,通过原位聚合和流延成膜法制备了不同TiO2含量的PI/TiO2杂化膜,研究了杂化膜的热性能、力学性能,并通过扫描电镜(SEM)和广角X衍射(WAXD)研究了杂化膜的微观形貌结构,同时也对杂化膜的接触角和介电常数(ε)进行了研究分析。结果表明,杂化膜较纯膜的热分解温度(T5%)降低,但平均热分解温度仍然高于520℃,且膜的尺寸稳定性得到了提高,即热膨胀系数(CTE)降低;表面形貌分析表明,1%～5%的表面改性纳米TiO2能较好地分散在PI膜里,杂化膜的介电常数(3.50左右)均高于纯膜的的介电常数(2.91),杂化膜的接触角随着TiO2含量的增加呈现先减少后增加的趋势。

A series of PI/TiO2 hybrid films based on 4,4′-oxydianiline（ODA） and 3,4,3′,4′-biphenyltetracarboxylic dianhydride（BPDA） were prepared via in-situ polymerization by incorporation with varied content of nano-sized TiO2,which was surface modified by silane coupling agent（mecaptopropyltriethoxylsilane）.The thermal stability,the coefficient of thermal expansion（CTE） and mechanical properties of the PI/TiO2 hybrid films were investigated.The microstructure was characterized by SEM,WAXD.The contact angle,dielectric property and ferroelectric property of hybrid films were also investigated.Research results showed that the introduction of nano-TiO2 lead to reduceing of thermal decomposition temperature.But the average T5% of hybrid films were still higher than 520oC,meanwhile,dimensional stability of hybrid films exhibited an increase,as represented by decreased CTE.The surface modified nano-TiO2 particles were homogenously dispersed in the polyimide hybrid film with TiO2 content between 1wt.% and 5wt.%.The PI/TiO2 hybrid films possessed the higher dielectric constant（approximately 3.50） than the pure PI film（2.91）.It was also showed that contact angle of hybrid films decreased with increasing of TiO2 doping content until 10 wt.%,to reach the maximum,and then decreased with further increasing of TiO2 content.