Glass-Transition Dynamics of Mixtures of Linear Poly(vinyl methyl ether) with Single-Chain Polymer Nanoparticles: Evidence of a New Type of Nanocomposite Materials

Abstract

Single-chain polymer nanoparticles (SCNPs) obtained through chain collapse by intramolecular cross-linking are attracting increasing interest as components of all-polymer nanocomposites, among other applications. We present a dielectric relaxation study on the dynamics of mixtures of poly(vinyl methyl ether) (PVME) and polystyrene (PS)-based SCNPs with various compositions. Analogous dielectric measurements on a miscible blend of PVME with the linear precursor chains of the SCNPs are taken as reference for this study. Both systems present completely different behaviors: While the blend with the linear precursor presents dynamics very similar to that reported for PVME/PS miscible blends, in the PVME/SCNP mixtures there are an appreciable amount of PVME segments that are barely affected by the presence of SCNPs, which nearly vanishes only for mixtures with high SCNP content. Interestingly, in the frame of a simple two-phase system, our findings point towards the existence of a SCNP-rich phase with a constant PVME fraction, regardless of the overall concentration of the mixture. Moreover, the dynamics of the PVME segments in this SCNP-rich phase display an extreme dynamic heterogeneity, a signature of constraint effects.

Disentangling Component Dynamics in an All-Polymer Nanocomposite Based on Single-Chain Nanoparticles by Quasielastic Neutron Scattering

“… 16 Interestingly, it was found a very different calorimetric and dielectric behavior of PS/PVME mixtures depending on whether the PS-component consisted of linear chains or of SCNPs. 17 , 18 In addition, the structural properties as well as the thermal behavior, the segmental and chain dynamics of systems based on poly(methyl methacrylate) (PMMA) SCNPs blended with linear poly(ethylene oxide) (PEO), were also studied during the last years. 19 − 21 Confinement effects on the PEO chains were reported.…”

Thermodynamic analysis of the phase equilibrium of the polystyrene‐poly(vinyl methyl ether) system

“…However, these data contradict the results of the subsequent studies. 23,25 The research into this system has been actively continued in the last 20 years [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] with the involvement of modern local structural and morphological methods such us fourier-transform infrared spectroscopy (FTIR), 36 small-angle neutron scattering (SANS), 37 Ultrafast differential scanning calorimetry (DSC), 39,41 and other. At the same time, the emphasis has shifted from phase diagrams to the analysis of the features of phase separation, 33,34,38,43 the influence of such external factors as pressure, 36 the effect of changes in the terminal groups of components, [30][31][32] their crosslinking, including hydrogen bonds, 29,35 and the dynamics of nanoparticles.…”

“…At the same time, the emphasis has shifted from phase diagrams to the analysis of the features of phase separation, 33,34,38,43 the influence of such external factors as pressure, 36 the effect of changes in the terminal groups of components, [30][31][32] their crosslinking, including hydrogen bonds, 29,35 and the dynamics of nanoparticles. 37,40,42,44 The effect of the replacement of one component for another (e.g., replacement of PVME with its copolymers with maleic anhydride, the use of deuterated, or branched PS) continued to be investigated. 32 There were works on modeling phase equilibria with LCST and UCST.…”

“…One of the classic systems with LCST is the polystyrene (PS)‐poly(vinyl methyl ether) (PVME) system. Despite numerous studies, 1,4,8–44 it still attracts much attention. It was most actively studied between 1971 and 1994, when more than100 phase diagrams were investigated, constructed, and studied.…”

“…The research into this system has been actively continued in the last 20 years 29–44 with the involvement of modern local structural and morphological methods such us fourier‐transform infrared spectroscopy (FTIR), 36 small‐angle neutron scattering (SANS), 37 Ultrafast differential scanning calorimetry (DSC), 39,41 and other. At the same time, the emphasis has shifted from phase diagrams to the analysis of the features of phase separation, 33,34,38,43 the influence of such external factors as pressure, 36 the effect of changes in the terminal groups of components, 30–32 their crosslinking, including hydrogen bonds, 29,35 and the dynamics of nanoparticles 37,40,42,44 . The effect of the replacement of one component for another (e.g., replacement of PVME with its copolymers with maleic anhydride, the use of deuterated, or branched PS) continued to be investigated 32 .…”