Local Polymer Dynamics in Polymer−C₆₀ Mixtures

Abstract

The complexity of intermolecular interactions in polymer-nanoparticle systems leads to spatial variations in structure and dynamics at both the meso- and nanoscale. Much of this behavior is manifested in properties such as the glass transition and the viscosity. Incoherent neutron scattering measurements of C60-polymer mixtures reveal that local polymer chain backbone motions in the glassy state are suppressed relative to those of the pure polymer. Moreover, the scattering spectrum of the melt suggests that the influence of C60 on polymer dynamics is limited to the vicinity of the particles at nanosecond time scales. A model is presented to reconcile these observations with the bulk dynamical properties exhibited by the mixtures.

Fullerene‐based processable polymers as plausible acceptors in photovoltaic applications

“…5). This is in accordance with the literature 88,89 and suggests that the fullerene molecules do not strongly interact with the PS chains. On the con-trary, the fullerene molecules preferentially interact with each other and tend to aggregate within the PS matrix.…”

Local Segmental Dynamics and Stresses in Polystyrene–C60 Mixtures

“…As can be seen, nanocomposite systems exhibit lower mobility when compared to their neat counterparts. The MSD of backbone carbons is depressed upon the addition of fullerenes, in good agreement with the neutron scattering observations of Kropka et al 6 In the inset to Figure 10, a logarithmic plot of the functions g(t) is presented. The scaling of g(t) ∼ t 1/2 is expected for the very short time behavior studied.…”

“…This leads to an estimated glass transition shift of around 1 K upon the addition of fullerenes. The T g -shift predicted by the MD simulations is in excellent agreement to the shift found by differential scanning calorimetry (DSC) measurements of Kropka et al 6 However, for some temperatures, the dynamical behavior of unfilled and filled systems yields completely indistinguishable results.…”

Polymer and spherical nanoparticle diffusion in nanocomposites

“…However in our data, the mechanism of reduction of diffusion in our simulation data, is not due to entropic barriers but due to nanoparticle interfacial area 93,94 Although the, experimental, nanocomposite system 24 considers immobile nanoparticles (of radius 13-25 nm) that are different than our simulated small nanoparticle composites, this is the only studied nanocomposite system which contains an attractive nanoparticle polymer interaction, and thus the nanoparticles are well dispersed in the polymer matrix. In order to estimate the local segmental dynamics, the bond autocorrelation C b (t), was calculated according to the equation: C b (t) =< P 2 [b(t)·b(0)] >, where P 2 is the second Legendre polynomial, b(t) is a unit vector aligned along the bond of a polymer, and the angular brackets indicate an average over all polymer bonds in the system.…”