Crystallization Kinetics and Structural Perturbation in Poly(ethylene oxide)-Melamine Blends under Quiescent Isothermal Conditions

This study investigates the interfacial and crystallization behavior of poly(ethylene oxide) (PEO) and its heterogeneous blend with melamine under isothermal quiescent conditions. In situ small-angle and wide-angle X-ray scattering, complemented by optical, thermal, and rheological analyses, reveal that melamine alters the crystallization pathway of PEO. Specifically, melamine increases nucleation density and promotes the formation of denser spherulites, while simultaneously restricting chain mobility and suppressing long-range crystalline order. Interfacial interactions, most likely hydrogen bonding between melamine and the ether oxygen atoms of PEO, extend relaxation times and hinder lamellar periodicity. Despite a modest increase in crystallization temperature, the overall crystallinity decreases, highlighting the dual role of melamine as both a nucleating agent and a kinetic inhibitor. These findings provide a molecular-level framework for understanding the regulation of polymer crystallization by small organic molecules through interfacial coordination, offering insights for the design of polymer-organic hybrid systems in energy storage, coatings, and packaging applications.