The implication of PMMA molecular weight on compatibility of SAN/ PMMA blends containing GO-g-PMMA hybrid compatibilizers

The molecular weight of a polymer is one of the most important factors defining material properties and per-formance. Within the current study, poly(styrene-co-acrylonitrile)/poly(methyl methacrylate) (SAN/PMMA) blends containing hybrid particles of graphene oxide-g-poly(methyl methacrylate) (GO-g-PMMA) were designed so that the molecular weight of the PMMA chains tethered on the GO particles was correlated with the molecular weight of the PMMA matrix. Hybrid particles were prepared using surface-initiated atom transfer radical polymerization (ATRP). The number average molecular weight of the matrix PMMA was Mn = 20,100 or 130,900 g/mol, while in the case of hybrids it was Mn = 5600, 27,300 or 191,600 g/mol. Two blend compo-sitions were investigated: SAN/PMMA= 70/30 and 90/10 wt/wt, and the content of GO-g-PMMA was 1 wt%. Based on rheological studies it was demonstrated that higher molecular weights of the matrix PMMA promoted the compatibility of SAN/PMMA due to the similar viscosity of both blend components. Furthermore, the length of the PMMA chains grafted to the GO influenced the viscoelastic response of the material, resulting in different relaxation behavior as confirmed by mean relaxation times calculated from Cole-Cole plots. In addition, the effect of neat GO and GO-g-PMMA particles on the blend morphology and size distribution of PMMA droplets was discussed based on rheology and TEM analyses.

Automated summary

The molecular weight of a polymer is a crucial factor in determining material properties. In this study, a novel polymer blend was designed by correlating the molecular weight of poly(methyl methacrylate) (PMMA) chains tethered on graphene oxide (GO) particles with the molecular weight of the PMMA matrix. Rheological studies and TEM analyses were conducted to investigate the effects of molecular weight on blend compatibility, viscoelasticity, and morphology.