Chiorosulfonated block copolymers

Rubber-phase chlorosulforiated polystyrene-poly-(ethylene-butene-1)-polystyrene block copolymers were prepared by reaction of the block copolymer in solution with SO₂ and C1₂. Sample compositions ranged up to 7 weight percent sulfur and 29 weight percent chlorine contents as determined by X-ray fluorescence and infrared spectroscopy. A series of chlorosulfonated derivatives of an analogue of the elastomeric midblock were prepared and analyzed in similar fashion. A comparison of dynamic mechanical and dielectric behavior of solvent cast films of the block copolymer and midblock polymer materials indicates the existence of sulfonyl chloride dipole-dipole complexes in the solid state. Further evidence for the presence of such aggregates was obtained from analysis by Fourier-transform infrared spectroscopy. It appears that polystyrene domains in the block copolymer materials hinder this aggregation up to moderate concentrations of the sulfonyl chloride group as compared with the relatively unrestrained aggregate formation in the analogue midblock materials. At high levels of substitution, the formation of dipole aggregates disrupts the integrity of the polystyrene domain structure in the block copolymer materials, resulting in a reduction in mechanical strength.