Synthesis of hyperbranched polybenzoxazoles and their molecular composites with epoxy resins

Abstract

Hyperbranched aromatic polymers have attracted great attention recently because they combined the processability of hyperbranched polymers and the high-level performance of aromatic polymers. Here, a one-pot strategy for the synthesis of hyperbranched Polybenzoxazoles (HBPBOs) by polycondensation of 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane and 1,3,5-benzenetricarboxylic acid in Polyphosphoric acid was reported. The HBPBOs exhibited good solubility in organic solvents because of the branched structure and the flexible hexafluoropropane groups in main chains. The structure and terminal functional groups could be tailored by adjusting the molar ratio of two monomers. FT-IR, NMR and XRD measurements confirmed the structure of HBPBOs, while thermogravimetric analysis (TGA), UV-vis, and photoluminescence spectra, combined with the comparison with linear PBOs demonstrated the intriguing optical properties and good thermal stabilities of HBPBOs. The good solubility of HBPBOs also permitted their usage as molecular reinforcement for polymer composites as demonstrated in this study of HBPBOs/epoxy composites.

Hyperbranched polybenzoxazoles incorporated polybenzoxazoles for high‐performance and low‐Kmaterials

“…The pattern of FPBO exhibited diffraction peak at about 15.28, corresponding to d-spacing of 0.59 nm, which was assigned to the side-by-side interchain ordered packing. 35,36 Interestingly, such distance between interchains was slightly higher than our previously reported value of FPBO (0.54 nm) synthesized by one-step polycondensation, 24 suggesting the release of small molecules in the two-step thermal rearrangement might have repulsion effects between polymer chains, and thus increase the free volume in polymers, which was helpful to decrease the k values. The typical peak of face-to-face packing of polymer chains at 258, however, was very weak, which was attributed to the existence of bulk hexafluoropropane groups.…”

“…The detailed characterizations of the structure and properties of o-aminophenol-terminated HBPBO could be found in our previous paper. 24 In the second step of synthesis of FPHAs, the slight excess of TPC in the polymerization was also for the same purpose because the excess of TPC could ensure that most of the polymer chains were terminated by carbonyl chloride groups, thus facilitated the covalent bonding between HBPBO and FPHA. The precursor polymers were then thermally rearranged to our target products, HBPBO/FPBOs.…”

“…In this work, soluble fluorinated hyperbranched PBO (HBPBO) was firstly synthesized by onepot polycondensation of commercially available monomers in polyphosphoric acid. 24 Then different amounts of HBPBO were covalently incorporated into linear fluorinated poly(hydroxyamide) (FPHA), which were then converted to fluorinated PBO (FPBO) upon thermal annealing. [25][26][27] The effects of HBPBO on the structure and physical properties of FPBO were investigated, and the reduced dielectric constant were experimentally and theoretically demonstrated.…”

“…The utilization of aromatic HBPs as additives in the same linear polymer, especially for the purpose of reducing dielectric constant, has rarely been considered. In this work, soluble fluorinated hyperbranched PBO (HBPBO) was firstly synthesized by one‐pot polycondensation of commercially available monomers in polyphosphoric acid . Then different amounts of HBPBO were covalently incorporated into linear fluorinated poly(hydroxyamide) (FPHA), which were then converted to fluorinated PBO (FPBO) upon thermal annealing .…”

Synthesis and properties of a novel highly thermal stable N-propargyl monomer containing benzoxazole ring

“…21 From our previous results, the introduction of propargyl would enhance the solubility of highly heat-resistant resins and reduce the melting point of the monomers, 22,23 which is beneficial to their processing.…”