Abstract
The synthesis of telechellcs of poly(ether‐ether‐sulfones) (PEES) is controlled by high‐resolution gel‐permeation chromatography to optimize for low content of side products. Under optimum conditions the bifunctional polymer‐homologous series is formed to 99,9%. These telechrcs were used to synthesize block copolymers with aromatic polyesters. The polyesters (PE) contain phenylhdroquinone and terephthalic acid (semicrystalline liquid‐crystalline (LC) polyester), phenylterephthalic acid (amorphous LC polyester) or isophthalic acid (amorphous non‐LC polyester). Block copolymers with amorphous polyesters show one glass transition temperature depending on the composition but blends of corresponding homopolymers are biphase. Block copolymers with semicrystalline LC polyesters are phase‐separated. Incorporation of semicrystalline LC polyester segments into PEES increases their solvent resistance. The storage modulus of the block copolymer with 50 wt.‐% of the semicrystalline polyester shows the same temperature dependence as PEES. Homogeneous block copolymers show anisotropy only if the weight fraction of polyester is larger than 0,5 whereas phase‐separated systems show anisotropy at smaller fractions of polyester.