Hydrogen-Bonding-Driven\nSurface Fusion of Polymersomes\nand Fabrication of Multilayer Nanofilms

Self-assembly of block copolymers\nin selective solvents\nleads to\nthe formation of polymersomes, consisting of polymer shells around\nhollow voids. Polymersomes have been widely used in many different\nfields such as drug delivery, nanomedicine, and artificial cells.\nIn the applications of polymersomes, it is crucial to understand the\ninteraction between polymersomes and substrate surfaces. In this research,\nhydrogen bonding-driven surface fusion of polymersomes on solid surfaces\nis studied. Tannic acid (TA) molecules are adsorbed onto the surfaces\nof silica particles, leading to the synthesis of TA-coated silica\nparticles (SiO<sub>2</sub>-TA). Upon mixing poly[2-(dimethylamino)ethyl\nmethacrylate]-<i>block</i>-polystyrene (PDMAEMA-<i>b</i>-PS) polymersomes and SiO<sub>2</sub>-TA, polymersomes\nare adsorbed onto the surfaces of silica particles due to the hydrogen\nbonding interaction between PDMAEMA blocks and TA molecules. To gain\nfavorable interaction, the adsorbed polymersomes make lateral spreading\non the particle surfaces, which leads to deformation and surface fusion\nof the polymersomes. Bilayer structures with PDMAEMA blocks at the\ninner and outer layers and collapsed PS in the walls are produced\non silica particles after surface fusion of the polymersomes. It is\ndemonstrated that the mobility of the polymer chains in the polymersomes\nplays a key role in the surface fusion process. The formation of multilayer\nstructure through surface fusion of poly(acrylic acid)-<i>b</i>-polystyrene (PAA-<i>b</i>-PS) polymersomes on the PDMAEMA-<i>b</i>-PS-coated silica particles is studied. Driven by the hydrogen\nbonding interaction between PAA and PDMAEMA blocks, the adsorbed PAA-<i>b</i>-PS polymersomes make surface fusion on the PDMAEMA-<i>b</i>-PS bilayers, forming nanofilms with multilayer structures\non the silica particles.