Flexible All-Aromatic Polyesterimide Films With High Glass Transition Temperatures

A series all-aromatic poly(esterimide) s with different molar ratios of N-(3(')-hydroxyphenyl)-trimellitimide (IM) and 4-hydroxybenzoic acid (HBA) (IM/ HBA=0.3/ 0.7 and 0.7/ 0.3) was prepared with the aim to design flexible high T-g films. Melt-pressed films, either from high molecular weight polymer or cured phenylethynyl precursor oligomers, exhibit T(g)s in the range of 200 C-degrees to 242 C-degrees and are brittle. After a thermal stretching procedure, the films became remarkably flexible and very easy to handle. In addition, the thermally stretched 3-IM/ 7-HBA and 7-IM/ 3-HBA films show tensile strengths of 108 MPa and 169 MPa, respectively. Thermal treatment increased the Tg of 3-IM/ 7-HBA from 205 degrees C to 248 degrees C, whereas the Tg of 7-IM/ 3-HBA increased from 230 degrees C to 260 degrees C. (C) 2017 Wiley Periodicals, Inc.