聚酰亚胺不对称多孔膜的制备及表征

Preparation and characterization of polyimide asymmetric porous film

采用非溶剂诱导相转化法制备具有低导热系数的聚酰亚胺(PI)不对称多孔膜,考察成膜温度、涂膜厚度对聚酰亚胺多孔膜形貌和结构的调控作用及对各项性能的影响。采用傅里叶红外光谱仪(FT-IR)、热机械分析仪(TMA)、热重分析仪(TGA)、扫描电子显微镜(SEM)等对制备的聚酰亚胺多孔膜的热稳定性、孔结构与形貌等进行表征。结果表明:采用非溶剂诱导相转化法制备的聚酰亚胺多孔膜为不对称膜,且具有较低的导热系数;随着成膜温度的升高,薄膜的孔结构由指状孔逐渐变为海绵状孔,薄膜孔隙率由84.5%下降至72.5%,材料的导热系数由0.041 7 W/(m·K)降低至0.036 3 W/(m·K)后又升高;随着涂膜厚度的增大,指状孔与海绵状孔的孔径都增大,由于海绵状孔的数量增加,导致薄膜孔隙率下降,导热系数呈先降低后增大的趋势;孔隙率为86.6%时,导热系数低至0.032 6 W/(m·K)。

Polyimide asymmetric porous film with low thermal conductivity was prepared by non-solvent induced phase transformation. The effects of film forming temperature and coating thickness on the morphology and structure of polyimide porous films were investigated, and the thermal stability, pore structure and morphology of polyimide porous films were characterized by Fourier infrared spectrometer(FT-IR), thermomechanical analyzer(TMA), thermogravimetric analyzer(TGA) and scanning electron microscope(SEM). Results showed that the polyimide porous film prepared by non-solvent induced phase transformation was asymmetric and had low thermal conductivity. As the film forming temperature increased, the pore structure of the film gradually changed from finger-like hole to spongy hole, the porosity of the film decreased from 84.5% to 72.5%, and the thermal conductivity of the material decreased from 0.041 7 W/(m·K) to 0.036 3 W/(m·K) then increased. As the film thickness increased, the pore sizes of both finger-like holes and spongy holes increased, but the number of sponge holes increased, leading to a decrease in the porosity of the film, and the thermal conductivity tended to decrease first and then to increase. When the porosity was 86.6%, the thermal conductivity was as low as 0.032 6 W/(m·K).