Phase morphology and dynamic mechanical properties of model polyblock copolymers prepared from reactive oligomers

Two polyblock copolymer (BCP) series of the type (P/S)(n) (where P is the o ligomeric azo-initiator and S is the styrene block) synthesized by sequenti al (series A) and simultaneous (series B) photo-initiated polymerization we re characterized by small-angle X-ray scattering and by dynamic mechanical analysis. The molar mass characteristics of the BCP were little affected by methods of synthesis, whereas their morphologies and mechanical behaviour in the bulk state were widely different. Reasonably sharp SAXS peaks and di stinct log E' falls concomitant to the glass-rubber transitions for the mic rophases of each chain component for samples of series B were regarded as e vidence of a well-ordered, three-dimensional lattice of isolated S domains within a continuous P matrix. In contrast, the absence of well-defined SAXS peaks in the same range of scattering vectors combined with nearly two-fol d smaller log E' falls at T-gP for samples of series A suggested the existe nce of two co-continuous, randomly interpenetrated microphases of S and P b locks with a broad distribution of microheterogeneities by size.