Polymer architecture effect on rheology and segmental dynamics in poly (methyl methacrylate)-silica nanocomposite melts

Architecturally different polymer chains lead to fundamentally rheological responses and internal dynamics, which can be utilized rationalize advanced thermoplastic nanocomposites with tunable mechanical behavior. In this work, three model poly (methyl methacrylate) (PMMA) polymers linear, bottlebrush, star architectures the same total molar mass were investigated in their neat form, well-dispersed silica nanoparticles using rheology broadband dielectric spectroscopy (BDS). The master curves of dynamic moduli obtained by time-temperature superposition (TTS) over entire range from Rouse regime terminal flow a sequence significantly relaxation modes observed for samples linear branch chains. While form an entangled network, branched show viscoelastic response no sign rubbery entanglement plateau weak arm between flow, akin other polymers. Moreover, showed higher fragility index (m = 3.46 bottlebrush 5.36 star) compared 3.29) due dynamical heterogeneities induced relaxation. addition affects only regime, where whole chain motion is hindered attractive nanoparticles. dynamics segment performing (BDS) at frequency 10-2 Hz 107 Hz. results revealed more than 10 times slower segmental homopolymers slowdown α-relaxation process all composite form. composites temperature dependent pronounced low temperatures (leading approximately equal 80 nanocomposite PMMA 150 °C) prolonged interfacial matrix study have practical applications fields such as gas separation polymeric electrolyte membranes, simultaneous improvement mobility highly desired.