乙酯官能化聚酰亚胺的热致重排及其对CO2的吸附性能

先使两种含有邻羟基和大体积结构的二胺单体3,3’-二氨基-4,4’-二羟基四苯基甲烷(DDTPM)和9,9-双(3-氨基-4-羟基苯基)芴(BAHPF)分别与六氟二酐(6FDA)进行低温溶液缩聚反应并经化学酰亚胺化得到两种乙酯官能化的聚酰亚胺(PI)，然后在425℃氮气氛围中进行热处理制备出相应的热致重排(TR)聚合物。使用红外光谱仪(FTIR)、核磁共振波谱仪(NMR)、热重分析仪(TGA)、差示扫描量热仪(DSC)、X-射线光电子能谱(XPS)、X-射线衍射仪(XRD)以及Autosorb iQ2等手段表征两种PI和TR聚合物的结构和性能，研究了乙酯官能化聚酰亚胺的热致重排及其CO₂吸附性能。结果表明：PI(DDTPM-6FDA)和PI(BAHPF-6FDA)都发生了部分热致重排反应，且含有两个苯基的PI比含有芴基的PI具有更宽的重排温度范围。它们均具有较高的玻璃化转变温度(T_g)和较宽的晶面间距。TR(DDTPM-6FDA)和TR(BAHPF-6FDA)的比表面积分别为198和582 m²/g，孔径为0.42和0.44 nm，均为微孔聚合物材料，后者对CO₂的吸附能力更强。

Thermal Rearrangement of Acetate-functionalized Polyimides and Adsorption Properties for CO2

Two kinds of diamines containing ortho-hydroxyl groups and bulky moiety, 3,3'-diamino-4,4'-dihydroxytetraphenylmethane (DDTPM) and 9,9-bis (3-amino-4-hydroxyphenyl) fluorene (BAHPF) were polymerized respectively with aromatic dianhydride 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) via a low-temperature solution polymerization, and next, two acetate-functionalized polyimides (PI) were prepared via chemical imidization, and thirdly, which were further thermally treated at 425^oC in N₂ atmosphere to obtain the thermally rearranged polymers. Then, the structure and property of the PIs and TR polymers were characterized by means of Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), X-ray photoelectric spectroscopy (XPS), X-ray diffraction(XRD) and gas adsorption isotherms etc. The results show that the thermal rearrangement (TR) occured partially for both of the PI(DDTPM-6FDA) and PI(BAHPF-6FDA), and the PI containing two phenyl groups show a range of thermal rearrangement temperature broader than the PI containing fluorene moieties. They show high glass transitionn temperatures (T_g) and larger interplanar crystal spacing. After the thermal treatment at 425^oC, the specific surface area of TR(DDTPM-6FDA) and TR(BAHPF-6FDA) are 198 and 582 m²/g, and their pore diameters are 0.42 and 0.44 nm, respectively. They are belong to microporous materials, and the adsorption capacity for CO₂ of TR(BAHPF-6FDA) is higher than that of TR(DDTPM-6FDA).