Crystallization Kinetics of Poly(ethylene oxide) in All-Polymer Nanocomposites Based on Poly(methyl methacrylate) Single-Chain Nanoparticles

Understanding how single-chain nanoparticles (SCNPs) affect all-polymer nanocomposite performance is of crucial importance to tailor such materials. In this work, the crystallization kinetics and mechanical properties of all-polymer nanocomposites consisting of poly(methyl methacrylate) (PMMA) SCNPs dispersed in a poly(ethylene oxide) (PEO) matrix are systematically investigated. The crystallization behaviors of PEO are suppressed by the incorporation of either linear precursors or SCNPs. The nonisothermal crystallization measurements show the reductions in crystallization temperature, melting temperature, and crystallinity of PEO with increasing linear precursor or SCNP content. The results of isothermal crystallization reveal that the relative crystallinity, equilibrium melting temperature, and crystallization rate of linear blends and all-polymer nanocomposites are lower than those of neat PEO, and the addition of linear precursors or SCNPs changes the growth dimension of PEO crystals. Compared with linear blends, all-polymer nanocomposites exhibit weaker suppression on the crystallization kinetics of PEO. Dielectric relaxation results confirm less restriction on the motion of PEO segments and faster segmental dynamics in all-polymer nanocomposites, owing to the weaker interactions between SCNPs and PEO matrix resulting from the crumpled globular morphologies and small size feature of SCNPs. Moreover, all-polymer nanocomposites present higher tensile modulus and elongation at break, indicating the simultaneous strengthening and toughening effect of SCNPs. Such lower crystallinity, faster segmental relaxation, and excellent mechanical properties of all-polymer nanocomposites provide promising candidates for solid polymer electrolyte applications.