The role of carbon nanoparticles in epoxy‐based nanocomposites modified with (poly[polypropylene oxide]‐ block ‐poly[ethylene oxide]‐ block ‐poly[propylene oxide]) triblock copolymers on phase morphology and mechanical properties

The main goal of this work is to show the role of carbon nanoparticle geometry and poly(ethylene oxide):poly(propylene oxide) (PEG:PPG) ratio on the miscibility, morphology, and final properties of an epoxy resin modified with triblock copolymers PPG-block-PEG-block-PPG (PPG-b-PEG-b-PPG). The employed copolymers have different PEG:PPG ratios in their molecular structure. One of them is miscible and the other is immiscible in epoxy resin. The used carbon nanoparticles were multiwalled carbon nanotubes, graphene nanoplatelets, and carbon black in a concentration of 0.5 wt/wt% for all nanoparticles. Adding the nanoparticles did not influence the miscibility of the PPG-b-PEG-b-PPG copolymer in the resin. However, the different geometries of the nanoparticles interfered in the dispersion, reflecting on the mechanical and thermal properties of the epoxy-based nanocomposites. Nanocomposites in a miscible system with graphene nanoparticles showed a 10% increase in Young's modulus over the neat resin. Immiscible systems with carbon black nanoparticles presentedK(Ic)values 81% higher than the neat matrix, while the numerical valueK(Ic)was only 6.5% higher than the neat resin for the miscible ones. Besides, a synergistic effect was observed between the copolymer/nanoparticles on the toughness of the nanocomposites. Finally, the nanoparticles minimized the negative effect of the block copolymer on Young's modulus and the glass transition temperature of the neat resin.