Synthesis, Characterization And Multi-responsive Self-assembly Of Amphiphilic Carboxy-terminated Hyperbranched Polyesters

Hyperbranched polymers have obtained more and more attention for its unique chemical and physical properties. Hyperbranched polymers have a very special molecular structure, a large number of terminal functional groups, and can be functionalized through modification of the terminal functional group. In addition, hyperbranched polymers can be synthesized by simple one-step reaction. Therefore, Hyperbranched polymers have a lot of potential applications which include coating, additives, drug or gene delivery, supramolecular chemistry, and nanotechnology, etc. In recent years, the application of hyperbranched polymers in the field of self-assembly get rapid development, especially, in cytomimetic Chemistry. Reversible regulate on size and self-assembly/disassembly of vesicles can be obtained by stimulation responsive conditions such as temperature, pH and light ect to achieve the function of detection and release. It has caused great interest for the scientific. However, this research field exists some problem such as size of assemblies is too small to observe; the way of stimulation responsive behavior of assemblies is relatively onefold; the Reactive monomer of assembly molecular is almost not commercial available. In conclusion, this research topic study on synthesis of amphiphilic carboxy-terminated hyperbranched polyesters by simple one-step reaction and the fabrication of mult-responsive micron-sized vesicles based on pH, temperature and electrolyte. Simulate the function of encapsulation and release of drug which is observed by OM and FM, The main results are shown as follows:1.Synthesis, characterization of amphiphilic hyperbranched polyesters.Synthesis and characterization of amphiphilic hyperbranched polyesters (c-HBPE-PEG300, c-HBPE-PEG400, c-HBPE-PEG600) by simple one-pot reaction. The structure and properties of hyperbranched polyesters are characterized by FT-IR,1H-NMR,GPC, DSC, TGA.2.Fabrication of hyperbranched polyester vesicles and study on multi-responsive stimulative self-assembly.First of all, hyperbranched polyester vesicles are fabricated by way of synchronous-assembly. Morphology of vesicles is observed by OM, FM, SEM and TEM. Test on pH responsive of vesicles. The responsive progress is tracked by OM, TM and DLS. The results indicate that vesicles of c-HBPE are pH responsive. Secondly, study on the temperature responsive of c-HBPE vesicles. The responsive progress is tracked by OM, TM. And the LCST of vesicles is 31.5℃,33℃,37℃ respectively. The results indicated that c-HBPE vesicles have temperature responsive.In the end, test on temperature responsive and electrolyte responsive of c-HBPE in methanol/ethanol. It is found experimentally that c-HBPE can be self-assembly under methanol or ethanol. Test on temperature responsive of vesicles. The assembly liquor change from turbid state to clear state with temperature rising. Test the transmittance of assembly liquor at different temperature by TM. The UCST is 40℃. The responsive stability is verified by trial and error. Test on electrolyte responsive of vesicles. It is found experimentally that the assembly liquor change from turbid state to clear state by dropping one drop of solution of NaCl immediately. The change of transmittance is tested by TM. The responsive stability is verified by trial and error. It is indicated that c-HBPE shows electrolyte responsive in methanol/ethanol.3. Function simulation of drug encapsulation and drug release of c-HBPE vesiclesFirst of all, synchronous-assembly of c-HBPE-PEG300 and rhodamine B. Dialytic assembly liquor is observed by OM and FM based on micron-sized vesicles. Vesicles of red cavity and vesicles of glow lumen is observed by OM and FM respectively which indicates that vesicles encapsulate rhodamine B successfully. Function of drug encapsulation is simulated.Secondly, adjust pH of assembly liquor of vesicles encapsulating rhodamine B by dropping solution of NaOH. Assembly liquor changes from red turbid station to red clear station. It gets turbid again by dialysis. Redness of cavity and glow of lumen observed by OM and FM respectively disappeared which indicates that vesicles release rhodamine B successfully by adjusting the pH of assembly liquor. Function of drug release is simulated...