Hydrogen bonding induces unusual self-assembled structures from mixtures of two miscible disordered diblock copolymers

We synthesized two miscible disordered diblock copolymers, poly(methyl methacrylate– b –vinylphenol) (PMMA- b -PVPh) and poly(4-vinylpyridine– b –ethylene oxide) (P4VP- b -PEO), through anionic living and reversible addition fragmentation chain transfer polymerizations, respectively; together, these polymers contained one hydrogen bond donor (PVPh) and three hydrogen bond acceptors (P4VP, PEO, PMMA). The inter-association equilibrium constants ( K A ) for the three different hydrogen bonded pairs followed the order PVPh/P4VP ( K A  = 1200) > PVPh/PEO ( K A  = 280) > PVPh/PMMA ( K A  = 47.1), suggesting that the PVPh units prefer to hydrogen bond with P4VP block, rather than PEO and PMMA blocks. Nevertheless, the excluded PMMA and PEO segments experienced weak intermolecular dipole–dipole interactions, such that the PMMA- b -PVPh/P4VP- b -PEO blends exhibited two-phase behavior, forming miscible PVPh/P4VP and PMMA/PEO phases, as evidenced using transmission electron microscopy.