Preparation and characterization of fluorine-containing aromatic condensation polymers. VI. Aromatic polybenzothiazoles from 4,4?-(hexafluoroisopropylidene)dibenzoic acid and tetrafluoroterephthalic acid and 2,5-diamino-1,4-benzenedithiol dihydrochloride

Synthesis and Characterization of Aromatic Poly(benzobisthiazole)s and Poly[oxy(bisbenzothiazole)]s Containing Flexible Linkages

“…The incorporation of the bulky and polar 6F groups in the chain accounts for the latter finding, as they reduce the intermolecular forces between polymer chains and may establish stronger interactions with solvent molecules. These results and the data reported in the literature [8,9] confirm that, in the case of poly(benzobisthiazole)s, a limited solubility in organic solvents can be reached only by introducing perfluoroisopropylidene groups into the main chain. However, a fair enhancement of the solubility was observed for PBTs I a and II c, which have oxygen bridged benzothiazole moieties.…”

“…After the dehydrochlorination of 5, performed at 70 8C, high temperatures and long reaction times were used, following well established synthetic procedures for PBTs. [8,9,13] The polymerization results are reported in Table 1. Considering the presence of several flexible linkages in the chain repeat units of these PBTs, the g inh values, ranging from 0.62 to 2.68 dL/g, are indicative of moderate polymerization degrees.…”

“…As for other rigid etheroaromatic polymers, such as poly(oxadiazole)s [4] or poly(benzoxazole)s, [5 -7] considerable research efforts have been directed toward modifying the chemical structure of rigid-rod PBTs using specialized monomers in order to improve their solubility and/or to lower their transition temperatures while preserving high thermal stability. The modifications reported were obtained using fluorinated [8,9] or non-coplanar monomers, [10] by attaching flexible side chains [11,12] or bulky aromatic substituents [13] and incorporating diphenoxybenzene units [14,15] into the polymer backbone. The PBT derived from 4,49-(hexafluoroisopropylidene)dibenzoic acid and 2,5-diamino-1,4-benzenedithiol hydrochloride was found amorphous and exhibited improved solubility characteristics.…”

“…The PBT derived from 4,49-(hexafluoroisopropylidene)dibenzoic acid and 2,5-diamino-1,4-benzenedithiol hydrochloride was found amorphous and exhibited improved solubility characteristics. [8,9] The synthesis of soluble precursor polymers that can be converted into PBTs by heat Full Paper: Aromatic poly(benzothiazole)s (PBT)s were prepared by direct polycondensation of multi-ring dicarboxylic acids containing aryl ether or 2,29-hexafluoroisopropylidene flexible groups and 2,5-diamino-1,4-benzenedithiol (PBT I) or 3,39-oxybis(6-aminobenzenethiol) (PBT II) using poly(phosphoric acid) or poly(phosphoric acid)/ methanesulfonic acid as condensing agent and solvent. Inherent viscosities were in the range 0.62-2.68 dL/g, indicating moderate polymerization degrees.…”

Diacid architecture effect on the synthesis and microstructure of rigid‐rod poly(benzobisthiazole)s

“…Chemical modifications with organic‐soluble dopants of the final aromatic heterocyclic polymers were also mentioned, i.e., sulfonated PBIs. Fluorine‐containing aromatic polybenzothiazole was also synthesized; the amorphous structures showed good solubility in organic solvents with high thermal stability 20…”