Two cylinder-forming polystyrene-block-polybutadiene block copolymers of type A-B with antisymmetric composition (polymer PI with A : B = 3 : 1 (w/w) and polymer P2 with A : B = 1 : 3 (w/w)) and their binary mixture were studied by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) in order to determine the microphase structure. The cylindrical microstructure is confirmed for both copolymers, whereas, in the mixture, both techniques have unambiguously shown that a regular lamellar structure is obtained at the polymer-polymer composition P1 : P2 = 1 : 1 (ratio of the numbers of chains). Qualitatively, the same results are obtained for corresponding systems simulated by the cooperative motion algorithm (CMA). Direct observations of the structure as well as the cooperative structure factors determined in the strong segregation limit for the simulated systems indicated lamellar structures in the blend of composition P1 :P2 = 1 : 1, in contrast to the microfibrillar morphology of the copolymers. The simulation additionally indicated a polymer-polymer microseparation. The experimental and simulation results are compared with theoretical predictions based on the self consistent field theory.
Chain degradation of poly(α-methylstyrene) and polystyrene during dissolution of their nanocomposites with fullerene C 60 in solvents of different quality with respect to fullerene was studied in detail by size exclusion chromatography and UV spectroscopy. Chain ruptures have been shown to arise during swelling of composites but only for samples with entangled polymer matrix. The data obtained confirm that the hindered mobility of chains because of interaction of the entangled matrix with fullerene is the only cause of degradation. Chain rupture leads to radical depolymerization accompanied by covalent binding of fullerene with the chain fragments, which results in changing of the polymer matrix structure. Chain degradation indicates deterioration of the mechanical properties of the polymers in the presence of C 60 . The possibility of chain degradation in polymer-filler nanocomposites under deformation with the simultaneous observation of an apparent reinforcement effect because of the addition of filler in the polymer matrix is discussed.
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