Morphology evolution, conductive and viscoelastic behaviors of chemically reduced graphene oxide filled poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) nanocomposites during annealing

Abstract

The effect of chemically reduced graphene oxide (CRGO) on the phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) (PMMA/SAN) blends and the simultaneous response of rheological and conductive behavior of PMMA/SAN/CRGO nanocomposites upon annealing above the phase-separation temperatures were investigated. The introduction of CRGO causes the decrease of binodal temperature and the increase of spinodal temperature for PMMA/SAN blends and then enlarges their metastable regime. During annealing, the well-dispersed CRGO in the homogeneous blend matrix tends to be selectively located in the SAN-rich phase with the evolution of phase separation and then the CRGO further agglomerates effectively in the SAN-rich phase to form the conductive pathway. Thermal-induced dynamic percolation is observed for both the resistivity  and dynamic storage modulus G as a function of annealing time.The resistivity variation is ascribed to the agglomeration of CRGO in the SAN-rich phase, while the modulus evolution is attributed to the combined contribution of phase separation for blend matrix and the agglomeration of CRGO in the SAN-rich phase.

Effect of chemically reduced graphene oxide on the isothermal and non-isothermal phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) binary polymer blends

“…It is found that the slopes A are very similar for unlled and lled PMMA/ SAN (57/43) systems, indicating that the existence of CRGO has no effect on the sensitivity of the heating rate dependence of cloud point for PMMA/SAN blend with the near-critical composition. 46 It should be noted again that T c is different from the binodal temperature T b or the spinodal temperature T s , and the non-isothermal phase separation at the heating rate of 0.50 C min À1 for the blend matrix with near-critical or off-critical composition follows SD or NG mechanisms, respectively. Such result is also consistent with that found in PMMA/SMA blend.…”

“…43,44 Hydrazine hydrate (85%) was used as a reductant in the conversion of GO to CRGO. 46 CRGO was dispersed into methyl ethyl ketone (MEK) and the suspension was ultrasonicated for 15 min before adding PMMA/SAN with different compositions at 5 wt% to the suspension. 46 CRGO was dispersed into methyl ethyl ketone (MEK) and the suspension was ultrasonicated for 15 min before adding PMMA/SAN with different compositions at 5 wt% to the suspension.…”

“…This may indicate that the introduction of CRGO hardly changes the viscous diffusion essence of macromolecular chains during phase separation, but the mechanical barrier effect of CRGO on the macromolecular viscous diffusion may just result in the decrease of D app (T) and the postpone of t D and s(I m ). 46 Hence, when SAN is the minority of blend matrix (PMMA/SAN 57/43), the selective location of CRGO may result in more obvious viscosity increment and then more remarkable hindering effect on the SD phase separation behavior of blend matrix. Namely, the hindering effect of CRGO on the SD phase separation behavior of PMMA/SAN blend depends on the composition of blend matrix.…”

Phase separation behavior of poly(methyl methacrylate)/poly(styrene-co-maleic anhydride) in the presence of hollow silica nanotubes

“…[14][15][16][17] Extensive research has been mainly focused on the effect of spherical particles on the phase separation of polymer blends, for instance SiO 2 lled systems, such as polystyrene (PS)/poly(vinyl methyl ether) (PVME)/SiO 2 nanocomposites, 8,10,[18][19][20] poly(methyl methacrylate) (PMMA)/poly(styrene-co-acrylonitrile) (SAN)/SiO 2 nanocomposites, 9,[21][22][23] and polycarbonate (PC)/PMMA/SiO 2 nanocomposites. 24 The inuence of nanollers with other topological shapes on the phase separation of blend matrix has been also reported for one or two dimensional nanollers lled systems, such as PS/PVME/multiwall carbon nanotubes (MWCNTs) nanocomposites, [25][26][27] PMMA/SAN/MWCNTs nanocomposites, 1,28,29 PMMA/SAN/clay nanocomposites, 30,31 PMMA/ SAN/GO nanocomposites, 32 PMMA/SAN/chemically reduced graphene oxide (CRGO) nanocomposites 33,34 and PS/PVME/reduced graphene oxide (RGO) nanocomposites. 35,36 As a onedimensional rod-like ller, hollow silica nanotubes (HSNTs) have attracted special interest because of its easy surface functionalization, porous wall structure, hydrophilic nature, and biocompatibility, 37 which may have some potential applications in reinforced materials, catalyst carriers, sensors, hydrogen storage materials, drug storage and delivery.…”

Effect of grafted graphene nanosheets on morphology evolution and conductive behavior of poly(methyl methacrylate)/poly(styrene-co-acrylonitrile) blends during isothermal annealing

“…The setup for electrical behavior measurement was the same as reported elsewhere. [18][19][20] Volume resistance was measured using a digital picoammeter (Keithley 6487, Keithley Instruments Inc., USA) with an applied direct voltage of less than 10 V (DC). The isothermal annealing temperatures ranged from 180 to 200 C with a step of 10 C. Dynamic rheological tests were performed on an advanced rheometric expansion system (ARES-G2, TA Instruments Corporation, USA) with a 25 mm diameter parallel plate geometry.…”