Hydrogen-Bonding-Driven Surface Fusion of Polymersomes and Fabrication of Multilayer Nanofilms

Self-assembly of block copolymers in selective solvents leads to the formation of polymersomes, consisting of polymer shells around hollow voids. Polymersomes have been widely used in many different fields such as drug delivery, nanomedicine, and artificial cells. In the applications of polymersomes, it is crucial to understand the interaction between polymersomes and substrate surfaces. In this research, hydrogen bonding-driven surface fusion of polymersomes on solid surfaces is studied. Tannic acid (TA) molecules are adsorbed onto the surfaces of silica particles, leading to the synthesis of TA-coated silica particles (SiO2-TA). Upon mixing poly[2-(dimethylamino)ethyl methacrylate]-block-polystyrene (PDMAEMA-b-PS) polymersomes and SiO2-TA, polymersomes are adsorbed onto the surfaces of silica particles due to the hydrogen bonding interaction between PDMAEMA blocks and TA molecules. To gain favorable interaction, the adsorbed polymersomes make lateral spreading on the particle surfaces, which leads to deformation and surface fusion of the polymersomes. Bilayer structures with PDMAEMA blocks at the inner and outer layers and collapsed PS in the walls are produced on silica particles after surface fusion of the polymersomes. It is demonstrated that the mobility of the polymer chains in the polymersomes plays a key role in the surface fusion process. The formation of multilayer structure through surface fusion of poly(acrylic acid)-b-polystyrene (PAA-b-PS) polymersomes on the PDMAEMA-b-PS-coated silica particles is studied. Driven by the hydrogen bonding interaction between PAA and PDMAEMA blocks, the adsorbed PAA-b-PS polymersomes make surface fusion on the PDMAEMA-b-PS bilayers, forming nanofilms with multilayer structures on the silica particles.