Temperature-dependent compatibilizing effect of graphene oxide as a compatibilizer for immiscible polymer blends
Temperature-dependent compatibilizing effect of graphene oxide as a compatibilizer for immiscible polymer blends
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我们证明了氧化石墨烯（GO）在不混溶的聚（甲基丙烯酸甲酯）/聚苯乙烯（PMMA/PS，80/20）共混物的增容效果，并表明，这种增容效果的影响的加工温度。对于在相对低的温度（190 °C）下制备的共混物，引入0.5wt%的GO导致分散的次要相（PS）的微区直径的显著减小，表明GO是有效的增容剂。加工温度的升高降低了分散相尺寸的减小，说明GO的增容作用与加工温度相反。表征结果包括GO的化学组成的变化和共混物在不同的退火温度下的形态演变表明，这种温度依赖性增容效果应归因于在熔融加工过程中的原位热还原GO，这打破了亲水性-疏水性平衡，使其更疏水。对比实验表明，化学还原GO对PMMA/PS共混物几乎没有增容作用，这进一步证实了所提出的机理。此外，GO增容共混物的力学性能比未增容共混物有很大的改善。
We demonstrated the compatibilizing effect of graphene oxide (GO) in the immiscible poly(methyl methacrylate)/polystyrene (PMMA/PS, 80/20) blend and showed that such a compatibilizing effect was affected by the processing temperature. For the blends prepared at a relatively low temperature (190 °C), the incorporation of 0.5 wt% of GO results in a dramatic reduction in the domain diameter of dispersed minor phase (PS), indicating that GO is an effective compatibilizer. Increasing the processing temperature decreases the dispersed phase size reduction, illustrating that the compatibilizing effect of GO is adverse to processing temperature. The characterization results including the changes in chemical composition of GO and morphologies evolution of blends at different annealing temperatures reveal that this temperature-dependent compatibilizing effect should be attributed to the in situ thermal reduction of GO during the melt processing, which breaks the hydrophilicity-hydrophobicity balance of GO and renders it more hydrophobic. A comparative experiment shows that chemically reduced GO has almost no compatibilizing effect for PMMA/PS blends, which further confirms the proposed mechanism. In addition, the GO-compatibilized blends exhibit great improvement in the mechanical properties than uncompatibilized blends.