Dielectric and thermal behaviors of fluorine‐containing dianhydride‐modified polybenzoxazine: A molecular design flexibility

Abstract

Fluorine-containing copolybenzoxazines were successfully prepared by reacting bisphenol-AF/aniline-based benzoxazine resin (BAF-a) with 4,4 0 -(hexafluoroisopropylidene) diphthalic anhydride (6FDA) in N,N-dimethylacetamide solvent. The dielectric and thermal properties as well as flexibility of the resulting copolymer films were investigated. The incorporation of fluorine groups into polybenzoxazine was found to substantially decrease the dielectric constant of the resulting copolybenzoxazine to as low as 2.6. The formation of ester linkages between the hydroxyl groups in the poly(BAF-a) and the carbonyl groups in the 6FDA resulted in substantially enhanced flexibility of the copolybenzoxazines. Moreover, the copolymers showed superior degradation temperature and significant improvement in char yield, up to 464 8C and 56%, respectively. The glass-transition temperature of the copolybenzoxazines was increased with increasing dianhydride content and exhibited a maximum value of 290 8C at 2.5/1 mole ratio of poly(BAF-a) to 6FDA. Therefore, the fluorine-containing dianhydride-modified polybenzoxazines are appropriate for applications as polymeric films for coatings and as a good electrical insulation material with high thermal resistance.

Benzoxazine Containing Fluorinated Aromatic Ether Nitrile Linkage: Preparation, Curing Kinetics and Dielectric Properties

“…Thermosetting and thermoplastic materials containing fluorine were designed and prepared. The researchers investigated various kinds of benzoxazine resins containing fluorinated groups such as bisphenol-AF [20], 1,4-tetrafluorobenzene or 4,4-octafluorobiphenylene dioxyphenylene [21,22] in molecular chains. The results indicated that the introduction of fluorine can serve the reducing of dielectric constants and dielectric loss.…”

Synthesis and Characterization of Pyrimidine‐Based Novel Phthalonitrile Resins with Excellent Processing Performance and High Glass Transition Temperature

“…The absorption band at 1597 cm −1 and 1398 cm −1 were corresponding to −C=N and −C−N of pyrimidine ring, respectively, and the signal of −C−O−C− appeared at 1276 cm −1 [18] . While the absorption peak at 2974 cm −1 belonged to −C−H for PBAD and PBAD‐1, the characteristic absorption signal of −C−F for PBFD, PBFD‐1 and PBFD‐2 appeared at 1172 cm −1 [19] . During the curing process, the cyano groups on the monomers were cross‐linked to form polyindoline, polytriazine and phthalocyanine structures, which were detected at 1730 cm −1 , 1357 cm −1 , 1012 cm −1 , respectively, indicating the successful synthesis of PBPD‐1 and PBPD‐2 [20] .…”

“…[18] While the absorption peak at 2974 cm À 1 belonged to À CÀ H for PBAD and PBAD-1, the characteristic absorption signal of À CÀ F for PBFD, PBFD-1 and PBFD-2 appeared at 1172 cm À 1 . [19] During the curing process, the cyano groups on the monomers were cross-linked to form polyindoline, polytriazine and phthalocyanine structures, which were detected at 1730 cm À 1 , 1357 cm À 1 , 1012 cm À 1 , respectively, indicating the successful synthesis of PBPD-1 and PBPD- 2. [20] Compared with the spectra of monomer PBPD, the absorption peak at 2231 cm À 1 of PBPD-1 and PBPD-2 were significantly weakened but still remaining, which might be due to the large volume of the polytriazine ring impeded the further reaction of cyano groups.…”

Development of an Atomic-Oxygen-Erosion-Resistant, Alumina-Fiber-Reinforced, Fluorinated Polybenzoxazine Composite for Low-Earth Orbital Applications

“…Both degradation temperatures are considered quite high. The char yield, on the other hand, is very low for benzoxazines, particularly for those containing a CF 3 group, which is typically in the range of 36–68% [ 7 , 11 , 12 , 17 , 19 , 23 , 23 , 27 , 34 ], or a furan group, which is typically between 30–74% due to high crosslinking capabilities [ 41 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ]. The char yield at 800 °C was approximately 24%, which is unexpectedly low for a benzoxazine such as BAF-oda-fu, which contains both above functionalities.…”

“…The synthesis of fluorinated benzoxazines requires rather different conditions from the ordinary, non-fluorinated benzoxazines due in part to the strong electron-withdrawing tendency of the CF group. Fluorinated benzoxazines have been reported in the literature [ 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Polybenzoxazines derived from fluorinated monomers are studied for their special synthesis methods [ 8 , 15 , 23 ], low dielectric constant properties [ 9 , 10 , 19 , 27 , 29 , 32 , 34 ], structure–property relationships [ 7 , 11 , 28 , 30 ], fuel cell applications [ 13 ], low surface free energy or superhydrophobicity [ 12 , 14 ], and high thermal properties [ 16 , 17 , 18 ,…”