Segmental Dynamics of Polymer Melts with Spherical Nanoparticles

Abstract

The impact of spherical nanoparticles (NPs) on the segmental dynamics of polymer melts is investigated. The addition of NPs broadens the segmental dynamics with effects of both particle size and loading. Interfacial bound layer thickness is calculated by the difference in magnitude of the segmental dynamics of pure polymer and nanocomposites. These theoretical models suggest that the bound layer thickness in the case of strongly adsorbing polymer matrices may increase with particle size.

Effects of surface modification and thermal annealing on the interfacial dynamics in core–shell nanocomposites based on silica and adsorbed PDMS

“…Similar values can be compatible with our results and the above models about polymer chain conformations (Scheme 1) of the bound polymer layer(s), taking into consideration that the length of Kuhn segment for a PDMS in melt is $1.56 nm [72]. However, the geometrical models employed previously for the estimation of interfacial layer thickness [8,9,15] cannot not be employed here, due to the high degree of initial particles aggregation [17], the not well defined shape of aggregates (SEM images in [17]), and the significant intraparticle porosity [36]. Nevertheless, we may calculate the 'apparent' interfacial layer thickness in our core-shell nanocomposites from the fraction of interfacial polymer, estimated above, and the specific surface area of the oxide sample before polymer adsorption, S BET , determined by nitrogen adsorption-desorption measurements (Table 1).…”

“…The properties of interfacial polymer may affect significantly or even dominate the behavior of the whole system [14]. Kumar and coworkers have demonstrated that the interfacial layer thickness in the case of strongly adsorbing polymers may increase with particle size [15] and decrease with curvature of the nanoparticles (Ref. 7 in [15]).…”

“…Kumar and coworkers have demonstrated that the interfacial layer thickness in the case of strongly adsorbing polymers may increase with particle size [15] and decrease with curvature of the nanoparticles (Ref. 7 in [15]). In general, the polymer in the interfacial layer is thought completely immobile, as it does not demonstrate any additive contribution to segmental http://dx.doi.org/10.1016/j.eurpolymj.2015.07.038 0014-3057/Ó 2015 Elsevier Ltd. All rights reserved.…”

Unexpected Molecular Weight Effect in Polymer Nanocomposites

“…These adsorbed chains form an dynamic interfacial layer (DIL), which has distinct segmental mobility and other properties [7,[14][15][16][17][18][19][20][21][22][23], and is believed to directly correlate with many advanced macroscopic properties of PNCs [3,5]. However, despite the recent intensive discussions on the features of the DIL [18,19,[22][23][24][25][26][27][28], many of its characteristics, especially the basic relationship between the interfacial layer chain packing and the dynamics, are still missing. This strongly hinders our understanding of various phenomena in PNCs.…”

“…Adding silica nanoparticles to PVAc leads to several changes in the dielectric spectra (Fig.1) [15,[21][22][23]: (i) the α-relaxation peak (segmental dynamics) shifts slightly to lower frequency, broadens and decreases in amplitude; (ii) an additional contribution appears on the low-frequency side (α'-peak); (iii) the Maxwell-Wagner-Sillar's (MWS) polarization process appears at even lower frequency; and (iv) the conductivity changes. The α'-process, corresponding to the segmental dynamics in the interfacial layer [21,23] which was not resolved in previous studies [15,[21][22][23], is now clearly visible especially in the derivative spectra, ε' der (ω) = -π/2*∂ε'(ω)/∂ln(ω) (Fig.S2 in SM [33]), and the relaxation time distribution analysis (Fig.1b) (for details of this analysis see Ref. [41] and SM [33]).…”