Block copolymers with crystalline/amorphous, crystalline/polyelectrolyte and amorphous/polyelectrolyte blocks

Diblock and triblock copolymers containing polybutadiene (PB) with high 1.4-butadiene content and poly(tert-butyl methacrylate) (PtBMA) blocks were synthesized by anionic polymerization using high vacuum techniques. These polymers were transformed by homogeneous hydrogenation, using the Wilkinson catalyst, into block copolymers containing a semicrystalline polyethylene (PE) block and an amorphous semiflexible PtBMA block. Subsequent hydrolysis resulted in block copolymers with semi-crystalline (PE) and polyelectrolyte (poly(methacrylic acid), PMAA) blocks. The PB/PtBMA copolymer precursors were also converted by direct hydrolysis to PB/PMAA copolymers, and subsequently to PB/poly(sodium methacrylate) amorphous/polyelectrolyte block copolymers by neutralization with NaOH. The extent of the transformation reactions was determined by solution and solid-state NMR spectroscopy. The materials containing a semicrystalline block were also characterized by differential scanning calorimetry (DSC). Some preliminary results from DSC on the phase behavior (mixing of phases and interplay between organization in the amorphous and semicrystalline phases) of these new materials are also presented.