A Novel Method for Manufacturing High-Performance Layered Silicate/Epoxy Nanocomposites Using an Epoxy–Diamine Adduct to Enhance Compatibility and Interfacial Reactivity

To solve the bottlenecks of poor dispersion and weak interface in nanocomposites, a novel epoxy–diamine adduct (TMA) is synthesized by reacting the epoxy monomer with the curing agent diamine to functionalize montmorillonite (MMT), which is designed to have perfect compatibility and reactivity with the epoxy matrix. Then, pristine MMT and TMA–MMT are incorporated with epoxy resin to fabricate nanocomposites. The correlations between surface functionalization, morphology, and interfacial interaction of the sheets and the composites properties are systematically investigated. The results show that the adduct is successfully synthesized and is terminated with epoxy and amine groups. Improved dispersion/exfoliation with larger surface fractal and smaller gyration radius of TMA–MMT can be obviously observed. At 3 wt% MMT loading, both the strength and modulus obtained from tensile and flexural tests improve significantly (by ≈40%). Moreover, the nanocomposite exhibits excellent N₂ barrier properties. The gas permeability is dramatically reduced by 91% compared to that of the neat epoxy. A model for gas permeation in the nanocomposite reveals that the MMT platelets are homogeneously dispersed in the matrix. Consequently, the improved dispersion/exfoliation and enhancement of the properties confirm the superiority of the adduct generated from the matrix, providing a general method for the development of high-performance nanocomposites.