Copolymers of telechelic poly(2,6-dimethyl-1,4-phenylene ether) (PPE) segments and crystallisable T6T6T units (two-and-a-half repeating unit of nylon-6,T) of uniform length were synthesised. The influence of the T6T6T content (0–20 wt%), the purity of the telechelic PPE and uniformity of the T6T6T segment length on the thermal mechanical (DMA) properties were studied. The polymers are semi-crystalline materials with a high Tg/Tm ratio of above 0.8. Increasing the T6T6T content (0–20 wt%) has little effect on the Tg transition region, but the modulus of the rubbery plateau increases strongly (0–13 MPa) and the flow temperature increases slightly as well (260–275 °C). The materials are transparent when the T6T6T content is below 10 wt%. Surprisingly previous termcopolymersnext term based on telechelic PPE of narrow molecular weight distribution had lower crystallinity. The uniformity of the T6T6T segment length seems to have little effect on the properties of the copolymers as long as at least 70% of the units are of one length.