The effect of clay on the morphology and phase-separation behavior of poly（methyl methacrylate）/poly（styrene- co-acrylonitrile） （PMMA/SAN） blends and the variation of clay dispersion have been investigated. With the evolution of phase separation in PMMA/SAN, most of the clays are first located at the boundaries between PMMA and SAN, and then gradually move to the PMMA-rich domain, owing to the affinity of clay to PMMA. The introduction of clay causes the increase of binodal and spinodal temperatures of PMMA/SAN and enlarges their metastable region, indicating the phase stabilizing effect of clay on the matrix. But the influence of clay on the cloud points obviously depends on the composition of PMMA/SAN. The selective adsorption of PMMA on the clay results in the difference between the composition of surface layer and that of polymer matrix. Hence, the clay plays the role of an agent changing the conditions of phase structure formation.
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 p 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.
