The Phase Behavior Of Poly (Styrene-co-acrylonitrile) /Poly(Methyl Methacrylate) In Solution

The phase behavior in solution for poly(styrene-co-acrylonitrile)(SAN)/poly(methyl methacrylate) (PMMA) blends in which miscibility derives from the so-called "repulsion effect" were investigated by using rheological measurements. The influences of blend composition and solvent on the phase behavior of SAN/PMMA blend in solution were studied in this thesis.The viscosity of SAN/PMMA blend in various of solvent at different concentration, c, scaled by c* were measured. The results reveal that the viscosity increases slightly with increase of concentration in the region c < c*, but increases intensively when c > c*. When c/c* > 10, the viscosity is very close to η ∝ = (c/c*)^15/4, indicating the start of the concentrated region where polymers are entangled with each other. No difference could be observed in dilute solution with different blend composition, however a large discrepancy was seen in semidilute solution in various solvent. It was interesting that a negative discrepancy appeared in 30c* DMF solvent, nevertheless, first a negative and then a positive discrepancy in 30c* butanone and 1,2-dichloroethane solvent was observed with the increase of PMMA content in SAN/PMMA blend which is considered to be the result of salvation and the chain repulsion effect in the polymer blend system. The effective distance of the "repulsion effect" was estimate to be 10⁰～10¹ nm.Due to the low concentration of polymer solution elastic modulus, its dynamic rheological behavior can not be measured by usring the rheometer in our laboratory, therefore only the dynamic rheological behavior of semidilute solution, such as 30c* solution, was investigated. The result of frequency scanning shows that the degree of entanglment in blends enhances with the increase of PMMA content. In the solution of pure polymer, the solvents also have great impact on the entanglement of the macromolecular chain. Meanwhile, the relaxation spectrum and Cole-Cole curve also shows that there are different relaxation behavior and morphology in solution. This needs further exploration.In addition, this thesis also attempted to synthesize the styrene-propylene nitrile block copolymer using atom transfer radical polymerization method. Several impact factors in synthesizing have been studied.