通过交联抑制高温下氢键的解离提高聚酰亚胺的耐热性和尺寸稳定性

将炔基结构引入该聚酰亚胺主链中,通过热引发化学交联反应构建化学限域位点,抑制高温下氢键的减弱和解离,进而通过交联和高温下更加稳定的氢键协同性提升了该PI薄膜在高温下的尺寸稳定性.结果表明,相对于线性PI,交联后PI在400℃的强氢键含量达到26.1%,与未交联PI相比提高了近50%,从而将300~400℃范围的的热膨胀系数(CTE)从33.8×10?6/K降低至5.1×10^?6/K.最终制备的PI膜的Tg高达452℃,40~400℃范围内的CTE仅为2.1×10^?6/K,拉伸强度高达231 MPa,有望用于AMOLED的基底材料.

Heat Resistance and Dimensional Stability of Polyimide Improved by Inhibiting the Dissociation of Hydrogen Bonds at High Temperatures through Crosslinking

Polyimide(PI)containing benzimidazole structure exhibits good heat resistance and dimensional stability due to the intermolecular hydrogen bonding,which is regarded as promising substrate material for OLED flexible display devices.However,the dissociation of hydrogen bonds at high temperatures results in PI film high thermal expansion coefficient in the temperature range above 300℃,limiting the practicality of the PI film as the flexible display substrate material.In this study,the dianhydride containing alkynyl structure was introduced into the PI’s main chain,and chemically restricted sites were constructed by chemical crosslinking reactions to suppress the dissociation of hydrogen bonds at high temperatures,thereby improving the thermal performance of the PI film.The results show that,compared with linear polyimide,the hydrogen bonding content of PI at 400℃ is increased by nearly 50%after crosslinking.Correspondingly,the glass transition temperature of the chemically cross-linked PI film is as high as 452℃,and the thermal expansion coefficient in the range of 40?400℃ is only 2.1×10^?6/K.And the tensile strength of obtained PI film reaches 230.9 MPa.This PI film would be as potential substrate material for flexible display devices.