Bicontinuous\nBlock Copolymer Microparticles through\nHydrogen-Bonding-Mediated Dual Phase Separation between Polymer Segments\nand Fluorinated Additives

Bicontinuous\nmicroparticles have advanced transport, mechanical,\nand electrochemical properties and show promising applications in\nenergy storage, catalysis, and other fields. However, it remains a\ngreat challenge to fabricate bicontinuous microparticles of block\ncopolymers (BCPs) by controlling the microphase separation due to\nthe extremely narrow region of a bicontinuous structure in the phase\ndiagram. Here, we demonstrate a strategy to balance the phase separation\nof BCPs and fluorinated additives at different length scales in emulsion\ndroplets, providing a large window to access bicontinuous microparticles.\nThe key point is to simultaneously introduce contradictory attractive–repulsive\ninteractions between poly(4-vinylpyridine)-containing BCPs and carboxylated\nperfluorinated additives. Hydrogen bonding between poly(4-vinylpyridine)\nand carboxyl groups, as an attractive interaction, directs the microphase\nseparation between BCPs and additives. Meanwhile, the repulsive interaction\ndue to the high immiscibility between perfluoroalkyl residues and\nBCPs induces macrophase separation. The compromise of attractive–repulsive\ninteractions triggers the formation of bicontinuous microparticles\nin a large phase space. In addition, the vulnerable nature of hydrogen\nbonding provides a flexible route for reversibly shaping BCP assemblies.\nThis work establishes a platform for fabricating structured BCP microparticles\nof which the structures are hardly accessible through traditional\nsolution self-assembly.