Copolymers of poly(2,6-dimethyl-1,4-phenylene ether) and ester units

Copolymers of telechelic poly(2,6-dimethyl-1,4-phenylene ether) segments with terephthalic methyl ester endgroups (PPE-2T, 3700 g/mol) and different diols were made via a polycondensation reaction. The terephthalic endgroups of PPE-2T are stable during this reaction. The Tg of these polyether–ester copolymers decreases with increasing diol length and diol flexibility. The Tg can be set between 100 and 200 °C by changing the type of diol. However at increasing diol length the Tg becomes broader and the test bars are less transparent because the extent of phase separation increases with increasing diol length. Only polymers with a diol length up to C12 are homogeneous. Phase separation is probably enhanced by the bimodal molecular weight distribution of PPE-2T. Phase separation can be suppressed by using shorter PPE-2T segments with a short diol. It is even better to use fractionated, monomodal PPE-2T. Copolymerisation is much more effective in decreasing the Tg of PPE and therefore its processability than blending with polystyrene. It is expected that the processability of these copolymers is much better than that of PPE.