Abstract
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.
Highlights
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
Prior studies of confined polymers have revealed that thin films exhibit Tg values that are different from the bulk, and that this phenomenon was dependent on interfacial effects, i.e., the surrounding environment
For the smaller NPs, PSA-707 were synthesized with sodium-4-vinylbenzylsulfonate (PSA), and PSB, the (s,1,2) peak clearly deviates from a single line shape which can be phenomenologically reproduced by two Lorentzian curves
Summary
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. Zhu and coworkers[28] confirmed that the suppression in Tg of PS NPs with decreasing diameter was dependent on the presence (or lack) of surfactants (and surfactant type) at the nanoparticle interface These findings, corroborated by Christie et al.[29], supported the notion that interfacial effects strongly influenced the glassy dynamics of confined polymers, including for PS NPs. The leading argument for the observed confinement effects on the Tg of PS NPs is associated with the existence a polymer surface layer that is more mobile than the bulk-like core[26,27,28]. There remains a challenge to develop a technique that is capable of measuring the Tg of individual polymer NPs and to provide direct evidence of surface mobility for these confined systems
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
