One-Step Approach to Polyester–Polyether Block Copolymers Using Highly Tunable Bicomponent Catalyst

Phthalic anhydride and propylene/ethylene oxide are copolymerized at room temperature by a bicomponent metal-free catalyst comprising a mild phosphazene base and triethylborane. Provided with proper loadings of the two catalytic components, block copolymers with strict (AB)_nB_m type sequence structures and controlled molar mass (up to 60 kg mol^–1) can be generated in one synthetic step, and the block architecture can be enriched by the use of mono-, di-, or tetrahydroxy initiators. The obtained polyester–polyether block copolymers readily undergo microphase-separation in bulk and nanoaggregation in selective (aqueous and alcoholic) solvents.