Effect of Thermally Reduced Graphene Sheets on the Phase Behavior, Morphology, and Electrical Conductivity in Poly[(α-methyl styrene)-co-(acrylonitrile)/poly(methyl-methacrylate) Blends

Abstract

The effects of thermally reduced graphene sheets (TRG) on the phase separation in poly[(α-methyl styrene)-co-(acrylonitrile)]/poly(methyl-methacrylate) blends were monitored using melt rheology, conductivity spectroscopy, and electron microscopic techniques. The TRG were incorporated in the single-phase material by solution mixing. The composite samples were then allowed to phase separate in situ. The thermodynamics of phase separation have been investigated by monitoring the evolution of the storage modulus (G') as a function of temperature as the system passes through the binodal and the spinodal lines of the phase diagram. The phase separation kinetics were probed by monitoring the evolution of G' as a function of time at a quench depth well in the spinodal region. It was observed that TRG significantly influenced the phase separation temperature, the shape of the phase diagram and the rate of phase separation. The state of dispersion of TRG in the blends was assessed using electron microscopy and conductivity spectroscopy measurements. Interestingly, the composite samples (monophasic) were virtually insulators at room temperature, whereas highly conducting materials were obtained as a result of phase separation in the biphasic materials.

Effect of multiwall carbon nanotubes on the phase separation of concentrated blends of poly[(α-methyl styrene)-co-acrylonitrile] and poly(methyl methacrylate) as studied by melt rheology and conductivity spectroscopy

“…1), confirming the effect of the nanoparticles on the chain dynamics of the polymer components for these systems. A similar reduction of the phase separation temperatures was also observed for PMSAN/PMMA blends containing thermally reduced graphene sheets [14]. Also in this case, the graphene sheets showed a preferential localization in the PMSAN phase after phase separation [14].…”

“…A similar reduction of the phase separation temperatures was also observed for PMSAN/PMMA blends containing thermally reduced graphene sheets [14]. Also in this case, the graphene sheets showed a preferential localization in the PMSAN phase after phase separation [14]. In that case, effects were however already clear at concentrations of 1wt%, which might be caused by the larger surface to volume area of platelets as compared to tubes.…”

“…In addition, nanoparticles can impart intriguing properties to the blends such as morphological stability, electrical conductivity, structural integrity etc. Hence, the effect of nanoparticles on the compatibility and the phase separation process has been the subject of several experimental studies and simulations [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. For example, Balazs and co-workers [9] found numerically that hard mobile nanoparticles with a preferential affinity for one of the components, slow down the coarsening of the domains in the late stages of spinodal decomposition whereas particles with no preferential adsorption do not affect the phase separation kinetics.…”

“…Kim et al [26] observed that both the storage and loss modulus increase initially, followed by a decrease at longer time scales due to the coarsening of the cocontinuous structures. Particularly in the case of particle-filled blends for which optical techniques can often not be used, rheological techniques can provide essential information about the phase separation characteristics [8,[10][11][12][13][14]. However, in the case of dynamically symmetric blends, rheology can only pick up signals when the correlation length of the concentration fluctuations is large enough [10,13].…”

Magneto-optical harmonic susceptometry of superparamagnetic materials

“…Nanocomposite material properties not only depend on the properties of their constituent materials but also strongly depend on their morphology, dispersion, and interfacial characteristics of the constituents. [22][23][24][25][26][27] The increase in research on nanoscale materials has been driven by the ability to characterize these materials. 28 In order to further advance the field, new characterization techniques are necessary that are accessible to many researchers.…”