Self-assembly And Functionalization Of PH Responsive Polymer Vesicles

Compared with surfactant vesicles and liposome, polymer vesicles has much advantage, such as designable, stable and good penetrability. It is a challenge in the self-assembly field to make polymer vesicles more widely used. Otherwise, how to improve the complicacy of self-assembly to get better struction is very important to make the self-assembly science better developed. Here, we report a new kind of pH responsive complex vesicles made by two kinds of amphiphilic hyperbranched block polymer. We found the hierarchical self-assembly of the complex vesicles by increasing the pH of the solution. Then we used these complex vesicles as templating to get a series of size-controlled and wall-thickness-controlled silica hollow spheres.1. The hierarchical self-assembly behavior of the pH responsive complex behaviorTwo kinds of amphiphilic multiarm copolymers with a same hydrophobic hyperbranched poly[3-ethyl-3-(hydroxymethyl)oxetane](HBPO) core and different hydrophilic poly (ethylene oxide (PEO) and poly( 2-(dimethylamino)ethyl methacrylate)(DMAEMA) arms were synthesized by a"graft from"method. The obtained two polymers can complex together and will self-assemble in the water into pH-responsive giant vesicle around 1-10μm. The self-assembly behavior of the complex vesicle was studied by Zetasizer, laser scanning confocal microscopy (LSCM) and microscope. The results show that at PH that below iso-electric point (IEP), the complex vesicles were suspended randomly in the solution, and then the vesicles aggregated together to pearl necklace with the increase of pH. At an even higher pH, the vesicles aggregated to a three-dimensional macroscopic network like spider web. It is expected that the present work will give a new light on controlling the hierarchical self-assembly of vesicles and on the preparation of branched and network supramolecular systems.2. The silica hollow spheres by templating of complex vesiclesTwo kinds of different RA/C HBPO-star-PEO was used to combine with HBPO-star-PDMAEMA as templating to produce silica hollow spheres by addition of TEOS. At pH=8, TEOS hydrolyzed and deposit on the surface of complex vesicles. The morphology of the silica hollw spheres was studied by microscope and TEM. We found the size of the hollow spheres were in the dimension of micron and nanometer respectively. So we can control the size of the silica hollow spheres by using different HBPO-star-PEO. Otherwise, we get different silica hollow spheres of different wall thickness. The thickness corresponds to the amount of TEOS. Thus, we realized the control on both the size and wall thickness of the silica hollow spheres. This improved the level of controlling the mineralization by templating of polymer. and paved way for application of inorganic hollow nanopheres in catalysis, as the stationary phase for selective separation, controlled drug delivery, artificial cells, light fillers, low-dielectric-constant prosthetic materials and photonic crystals.