Chain Mobility Restrictions in Random Ionomers Studied by Electron Spin Resonance Spectroscopy

Abstract

Electron spin resonance (ESR) spectroscopy has been used to obtain information on chain mobility in spin-doped poly[styrene-co-(sodium methacrylate)] random ionomers. The results show that spin probe molecules randomly dispersed in ionomers respond to the matrix glass transition. However, when the probe molecules are anchored to the ionic multiplets, their mobility is reduced, indicating that the polymer segments adjacent to the ionic multiplets are constrained, and their mobility is restricted. Significant motions of the probe molecules start only when the kinetics of the ion-hopping process becomes relevant. Plasticization of the ionomers with polystyrene oligomers allowed for the simultaneous observation of two different mobility regimes, assigned to the matrix and cluster phases. These findings support the suggestion, which is a major component of the EHM model for the morphology of random ionomers, that regions of restricted mobility exist around the ionic multiplets.

Well-defined silica core–poly(vinyl pyrrolidone) shell nanoparticles: Interactions and multi-modal glass transition dynamics at interfaces

“…Really, a co-existence of both anomalously fast and ultraslow segmental dynamics modes in the glass transition could sometimes be observed [6,11,14,16,25,26]. Two glass transitions or anomalously shifted glass transition were observed in polymersilica nanocomposites [27][28][29][30]. Manias and Torkelson with co-workers published the first MD simulations/NMR [12,14] and fluorescence data [16] demonstrating the distribution of T g s across polymer film of several tens of nanometers in thickness [16], or a very wide distribution of segmental relaxation times in polymer confined in 1-2 nm wide slits (polymer-layered silicate nanocomposite) [14].…”

Indentation Fracture Mechanics for Toughness Assessment of PMMA/SiO2 Nanocomposites

“…[36][37][38] It has been described by Keddie et al [39] that there is a relationship between T g and film thickness. On the basis of these results we can deduce the following equation empirically:…”

Temperature dependence of molecular motions in the polyurethane-based membranes studied with paramagnetic spin probe

“…8). One possible explanation for this behaviour is motional broadening of the spectra caused by translational diffusion, which is also involved in the motion of the probe [23,24], and whose effect may become large at certain conditions. Therefore, it seems reasonable to find that the segmental motions of PUs with long soft segments are less constrained than in case of PUs with shorter ones.…”