Polybenzobisthiazoles – Critical issues in their performance and properties - Polyimides and Other High Temperature Polymers - page 229

(VIII) PBZT with hydroxy isophthalic acid

(IX) PBZT with dihydroxyterephthalic acid

BBL, Poly [(7-oxo-7, 1 OH-benz[de]imidazo[4,5;5,6]
benzimidazo[2,1-a]isoquinoline-3,4:10,11]-tetrayl)-10-carbonyl]

(X)

in monohydroxy PBZT. The model compounds were also synthesized using 2-
aminothiophenol and dicarboxylic acids, e.g., cyclohexane 1,4-dicarboxylic acid,
tetrafluorophthalic acid, 4-bromoisophthalic acid, isophthalic acid, and 5-hydroxy
isophthalic acid in order to compare the chemical structures of synthesized poly-
mers. Polybenzobisthiazole copolymer was also synthesized using thiophene -2,5-
dicarboxylic acid with cyclohexane 1,4 dicarboxylic acid and 2,5-diamino-1, 4-
benzenedithiol dihydrochloride.
The synthesized PBZTs were soluble in strong protic acids such as polyphos-
phoric acid (PPA), methanesulphonic acid (MSA) and chlorosulphonic acid
(CSA) [37-39]. Further, the structures of these synthesized polymers were estab-
lished by elemental analysis and FT-IR. As these polymers were insoluble in
common solvents so the solid-state NMR was carried out. The four intense bands
at 1602, 1454, 1308 and 1093 cm -1 in the FT-IR spectra were assigned to benzodi-