Hyperbranched Polybenzobisthiazole with High Thermal Stability, Good Organosolubility, and Interesting Optical Performance

A series of hyperbranched poly( p ‐phenylene benzobisthiazole)s (HBPBZTs) are synthesized by solution polycondensation of 2,5‐diamino‐1,4‐benzenedithiol dihydrochloride (DABDT, A 2 monomer) and 1,3,5‐benzene‐tricarboxylic acid (BTA, B 3 monomer). Their structure changes depending on the feed molar ratios (A 2 :B 3 ). The addition of DABDT and BTA (3:2) yielded HBPBZT with stoichiometry equivalent carboxyl and o ‐aminothiophenol end groups. By adding DABDT and BTA (1:1), carboxyl‐terminated HBPBZT is prepared. When the ratio of DABDT and BTA is 9:4, amino and sulfydryl‐terminated HBPBZT is obtained. These polymers are amorphous and exhibit good thermal stability. They are soluble in some common polar aprotic solvents. The HBPBZTs exhibit strong blue light in methansulfonic acid and in DMF solution. The type of solvent has a strong influence on optical properties of the HBPBZTs solution.