Preparation and Characterization of Thermally Stable Polybenzoxazole Copolymer Films Fabricated from Their Precursors

The polyhydroxyamide copolymers (F-PHAs) were synthesized by low-temperature solution polycondensation of 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAHHFP) and/or 3,3′-dihydroxybenzidine (DHB) with terephthaloyl chloride (TPC) in N,N -dimethylacetamide (DMAc) with the aid of lithium chlori...

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Veröffentlicht in:Fibers and polymers 2019, 20(12), , pp.2443-2452
Hauptverfasser: Kang, Chan Sol, Baik, Doo Hyun
Format: Artikel
Sprache:eng
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Zusammenfassung:The polyhydroxyamide copolymers (F-PHAs) were synthesized by low-temperature solution polycondensation of 2,2-bis(3-amino-4-hydroxyphenyl) hexafluoropropane (BAHHFP) and/or 3,3′-dihydroxybenzidine (DHB) with terephthaloyl chloride (TPC) in N,N -dimethylacetamide (DMAc) with the aid of lithium chloride (LiCl). A series of polybenzoxazole copolymer (F-PBO) films were fabricated via an efficient solution-casting and thermal-treatment technique, using their precursors (F-PHA films) with different BAHHFP fractions (25-100 mol%). The solubility results show that F-PHAs with higher BAHHFP content (≥75 mol%) are readily soluble in anhydrous DMAc and N -methyl-2-pyrrolidinone (NMP) without LiCl at room temperature. Differential scanning calorimetry (DSC) indicates that the thermal cyclization temperature of the F-PHA films decreases with increasing BAHHFP content. Thermogravimetric analysis (TGA) reveals that the F-PHA and F-PBO films are well prepared and completely converted. The UV-visible spectra indicate that the F-75-PBO film (BAHHFP content: 75 mol%) has reasonable transparency, with 84.9 % transmittance at 600 nm and 397-nm UV cut-off wavelength. It also has lower coefficient of thermal expansion (CTE) (48 ppm/°C) and water absorption (WA) values (0.14%). The BAHHFP as diamine component provides the final F-PBO film with desirable properties, e.g. , flexibility, thermal stability, transparency, and WA values.
ISSN:1229-9197
1875-0052
DOI:10.1007/s12221-019-1110-3