Highly branched poly(arylene ether)s via oligomeric A2 + B3 strategies

Branched poly(arylene ether)s were prepared in an oligomeric A 2 + B 3 polymerization of phenol endcapped telechelic poly(arylene ether sulfone) oligomers as A 2 and TFPPO as trifunctional monomer B 3 . The molar mass of the A 2 oligomer significantly influenced the onset of gelation and the DB. A high level of cyclization during polymerization of low molar mass A 2 oligomers (U 3 = 660 and U 6 = 1200 g mol -1 ) led to a high conversion of functional groups in the absence of gelation, and the level of cyclization reactions in the polymerization decreased as the molar mass of the A 2 oligomer was increased. The pronounced steric effect in the polymerization of higher molar mass A 2 oligomers (U 8 = 1 800 and U 16 = 3 400 g·mol -1 )raesulted in low reactivity of the third aryl fluoride in the B 3 monomer. As a result, only slightly branched (U 8 = 1800 g·mol -1 ) or nearly linear (U 16 =3400 g·mol -1 ) high molar mass products were obtained with higher molar mass A 2 oligomers. The branched polymers exhibited lower Mark-Houwink exponents and [η] relative to linear analogs, and differences between the branched polymers and linear analogs were less significant as the molar mass of the A 2 oligomers was increased due to a decrease in the overall DB.