Formation of nanophases in epoxy thermosets containing an organic–inorganic macrocyclic molecular brush with poly(ε-caprolactone)-block-polystyrene side chains

Abstract

In this contribution, we report the synthesis of organic–inorganic macrocyclic molecular brushes with a 24-membered macrocyclic oligomeric silsesquioxane (MOSS) backbone and with poly(ε-caprolactone) (PCL) (or poly(ε-caprolactone)-block-polystyrene (PCL-b-PS) diblock copolymer) side chains. The macrocyclic molecular brushes were incorporated into epoxy to access the nanostructured thermosets. The nanostructures in the thermosets were investigated by means of atomic force microscopy (AFM), small angle X-ray scattering (SAXS) and dynamic mechanical thermal analysis (DMTA). It is judged that the formation of the nanophases in the thermosets containing the macrocyclic molecular brush with PCL side chains (MOSS[PCL]₁₂) follows the self-assembly mechanism in terms of the immiscibility of the MOSS backbone with epoxy after and before the curing reaction. It was found that the spherical, vesicular and lamellar nanophases were formed in the epoxy thermosets containing the macrocyclic molecular brush with PCL-b-PS side chains (MOSS[PCL-b-PS]₁₂). In contrast to the thermosets containing MOSS[PCL]₁₂ the formation of the nanophases in the thermosets containing MOSS[PCL-b-PS]₁₂ was ascribed to the self-assembly-directed reaction-induced microphase separation mechanism.