Dispersion‐Dominated Noncovalent Stabilization with Weak Polarization‐Assisted O···H Contacts in the PMMA‐PS Polymer Framework

ABSTRACT Blending of polymers provides a cost‐effective strategy to tune properties of materials; however, a detailed understanding of interfacial and intermolecular interactions remains limited. In this work, we present the first density functional theory (DFT) based investigation of intermolecular interactions in the PMMA‐PS blend. Binding energy calculations revealed a favorable association (ΔE = −19.31 kcal/mol), while Xiamen energy decomposition analysis had a total interaction energy of −8.79 kcal/mol, indicating that noncovalent forces dominate thermodynamic stability. NCI, NBO, and AIM analyses showed that stabilization arises primarily from dispersion‐driven van der Waals interactions, with minor polarization‐assisted O···H interactions, characterized by low electron density at bond critical points (ρ = 0.003–0.012 a.u.) and weak stabilization energies (∼1 kcal/mol). Molecular electrostatic potential (MESP) mapping highlights complementary charge distributions at the interface. Ab initio molecular dynamics (AIMD) simulations confirm rapid structural relaxation (80–100 fs) and sustained stability at 310 K over 500 fs. By directly linking electronic‐structure interactions with blend stability, this work establishes a predictive molecular‐level framework for the rational design of PMMA‐PS‐based functional polymer materials.