Vesicle-polymer hybrid architectures: A full account of the parachute architecture

We have previously reported that polymerization of styrene in dioctadecyldi methylammonium bromide (DODAB) vesicles leads to so-called parachute-like m orphologies where a polymer bead is attached to a vesicle. To learn the con structive principles of these novel polymer colloids, we present here a ful l characterization study. The dual nature of these particles, combining int rinsic Vesicle features with polymer colloid properties, requires character ization methods that address both the morphology (cryo-TEM, AFM, DLS) and t he typical Vesicle characteristics (micro-DSC, fluorescence techniques, sur factant lysis). It is found that the vesicle characteristics after polymeri zation are virtually unchanged when compared to the bare vesicles. This obs ervation can be fully accounted for by the putative complete phase separati on between polymer and surfactant bilayer matrix. Several methods to releas e the polymer bead from its parental vesicle are presented. In a second par t we investigate the relation between polymerization reaction conditions (i .e., temperature, mode of initiation, molecular weight of the polymer) and the resulting vesicle-polymer hybrid morphology. Unexpectedly, slight modif ications in the reaction conditions prove to exert great influence on the p roduced morphology, resulting in novel vesicle-polymer architectures. It tu rns out that these variations in morphology are governed by intrinsic vesic le properties. As a general phenomenon, we find that polymerization of styr ene in DODAB vesicles-independent of process parameters-inevitably leads to microphase separation between the amphiphilic bilayer matrix and polymer.