Formation of genus vesicles in dilute aqueous solution by PtBAx‐b‐PS130‐b‐PEO90‐b‐PS130‐b‐PtBAx amphiphilic pentablock terpolymers

Abstract

AbstractA series of linear symmetrical ABCBA pentablock terpolymers, poly(tert‐butyl acrylate)‐b‐polystyrene‐b‐poly(ethylene oxide)‐b‐polystyrene‐b‐poly(tert‐butyl acrylate) with constant lengths of PS and PEO blocks but different degree of polymerization x of PtBA block, namely PtBAx‐b‐PS130‐b‐PEO90‐b‐PS130‐b‐PtBAx (x = 40, 75, 100, 165, and 200), were found to form various vesicular nanostructures in dilute aqueous solution as observed by conventional transition electron microscopy (TEM), cryogenic transmission electron microscopy (cryo‐TEM) and scanning electron microscopy (SEM). Genus vesicles with nanometer sizes and various genus values (g), including individual spherical vesicles, tubular vesicles (g = 0), toroidal vesicles (g = 1) and the vesicles with even larger g values (g > 1) were observed, respectively. The g value of genus vesicles formed by PtBAx‐b‐PS130‐b‐PEO90‐b‐PS130‐b‐PtBAx pentablock terpolymers decreased with the increasing length of PtBA block. The formation mechanism of genus vesicles was preliminarily discussed by the combination of membrane bending energy, the area‐difference‐elasticity and the edge effect.