• Fytas, George
• Priestley, Rodney D.
• Graczykowski, Bartłomiej
• Kang, Eunsoo
• Montagna, Maurizio
• Cang, Yu
• Furst, Eric M.
• Kim, Hojin
• Secchi, Maria

Abstract

<p>Measuring polymer surface dynamics remains a formidable challenge of critical importance to applications ranging from pressure-sensitive adhesives to nanopatterning, where interfacial mobility is key to performance. Here, we introduce a methodology of Brillouin light spectroscopy to reveal polymer surface mobility via nanoparticle vibrations. By measuring the temperature-dependent vibrational modes of polystyrene nanoparticles, we identify the glass-transition temperature and calculate the elastic modulus of individual nanoparticles as a function of particle size and chemistry. Evidence of surface mobility is inferred from the first observation of a softening temperature, where the temperature dependence of the fundamental vibrational frequency of the nanoparticles reverses slope below the glass-transition temperature. Beyond the fundamental vibrational modes given by the shape and elasticity of the nanoparticles, another mode, termed the interaction-induced mode, was found to be related to the active particle–particle adhesion and dependent on the thermal behavior of nanoparticles.</p>

Topics

• nanoparticle
• impedance spectroscopy
• surface
• polymer
• mobility
• glass
• glass
• elasticity