Microstructure and performance of block copolymer modified epoxy coatings

•Two distinct diblock copolymers were synthesized as modifiers for an epoxy resin.•Modifiers self-assembled into spherical micelles in cured bulk epoxy and coatings.•Toughened bulk thermosets showed a fivefold increase in the fracture toughness.•Modified epoxy coatings have a greatly enhanced abrasive wear resistance.•Block copolymer modification did not sacrifice other desired properties. The effects of two diblock copolymers, poly(ethylene-alt-propylene)-b-poly(ethylene oxide) (PEP–PEO) and poly(1,2-butadiene)-b-poly(2-vinyl pyridine) (PB–P2VP) on the mechanical properties of epoxy coatings were studied. Both modifiers self-assembled into spherical micelles of 10–20nm diameter in cured bulk epoxy. This morphology was preserved in 15μm thick coatings; however, micelle segregation to the coating/substrate interface was also observed. The critical strain energy release rate, G1c, of bulk thermosets was enhanced by up to fivefold with the addition of block copolymers. Likewise, the abrasive wear resistance of thin coatings increased with modifier inclusion. The results showed that at 5wt.% of loading, block copolymers were able to impart a 40% increase in abrasive wear resistance to modified coatings over neat ones. Block copolymer modifiers did not sacrifice the modulus and glass transition temperature of bulk thermosets and coatings, or the hardness and transparency of coatings.