Branched poly(arylene ether)s were prepared in an oligomeric A2 + B3 polymerization of phenol endcapped telecholic poly(arylene ether sulfone) oligomers as A2 and TFPPO as trifunctional monomer B 3. The molar mass of the A2 oligomer significantly influenced the onset of gelation and the DB. A high level of cyclization during polymerization of low molar mass A2 oligomers (U3 = 660 and U6= 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 A2 oligomer was increased. The pronounced steric effect in the polymerization of higher molar mass A2 oligomers (U8 = 1800 and U 16 = 3400 g · mol-1) resulted in low reactivity of the third aryl fluoride in the B3 monomer. As a result, only slightly branched (U8=1800 g · mol-1) or nearly linear (U16 = 3400 g · mol-1) high molar mass products were obtained with higher molar mass A2 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 significantas the molar mass of the A2 oligomers was increased due to a decrease in the overall DB.
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