posted on 2021-09-16, 12:05authored byHyeonil Kim, Hyeonuk Yeo, Heung Cho Ko, Nam-Ho You
A series
of aromatic polybenzoxazoles (PBOs) containing sulfur
atoms in their main chains were developed. All of the PBOs were prepared
from synthesized hydroxyl-diamine 4,4′-bis(4-amino-3-hydroxyphenylthio)diphenylsulfide
(3SDA) and aromatic diacyl chlorides, such as 4,4′-((thiobis(4,1-phenylene))bis(sulfanediyl))dibenzoyl
chloride (3SDBC), trans-1,4-cyclohexanedicarbonyl
dichloride (trans-CHDC), isophthaloyl dichloride
(IPC), and 4,4′-oxybis(benzoyl chloride) (OBC), via a conventional
two-step procedure. The PBOs exhibited high thermal stability, thermal
decomposition temperature (>430 °C), and glass-transition
temperature
(204–255 °C). The PBO derived from 3SDA and 3SDBC exhibited
a very high refractive index, i.e., 1.7862 at 637 nm due to the high
sulfur content (21.79%).