Molecular dynamics investigation of interfacial energy and mechanical behavior in braid-reinforced hollow fiber membranes

Abstract This study presents a comprehensive molecular dynamics (MD) investigation of braid-reinforced hollow fiber membranes (BRHFMs) to elucidate the interfacial and mechanical behaviors of polymeric composites composed of cellulose acetate (CA) and polyacrylonitrile (PAN). The analysis focuses on three representative configurations—homogeneous (CA/CA-II), semi-heterogeneous (PAN|CA/CA-I), and heterogeneous hybrid (CA/PAN-III)—to evaluate their interfacial energies, adhesion mechanisms, and tensile responses. The calculated interfacial energies of − 1.20 eV, − 1.45 eV, and − 1.61 eV for CA/CA-II, PAN|CA/CA-I, and CA/PAN-III, respectively, reveal that chemical homogeneity promotes stronger interfacial bonding, whereas polarity mismatches between functional groups (–OH, –OCOCH₃, and –CN) weaken adhesion and increase diffusivity at the interface.Mechanical testing through MD tensile simulations further demonstrates that the CA/PAN-III composite exhibits pronounced stress fluctuations and higher local interfacial activity. At the same time, the CA/CA-II system maintains the highest cohesive stability and elastic modulus due to structural uniformity. The CA/PAN-III hybrid achieves an optimal balance between flexibility and strength, indicating its suitability for water treatment membranes requiring both mechanical resilience and interfacial durability. These findings provide molecular-level insight into how polymer compatibility governs the performance of BRHFMs and offer valuable guidelines for designing next-generation high-strength composite membranes.