Synthesis And Properties Of Water Soluble Polymers With Amino Pendant Groups

In the field of polymer science it has been of great interest to combine properties of useful functional groups and polymers, especially well-defined block copolymers. The application of this approach provides a prospect of modifying polymer constitution to discovery new type of polymer which can be used as a pharmacological tool. Aminated polyelectrolytes have caused a great deal of attention because of their applications in drug delivery, immobilization matrices for enzymes and cells, and tissue engineering. As a matter of fact, the incorporation of primary amino groups onto the polymer backbone can tune both stabilization of polymer fragment and the useful biological activity of amino groups, which are among the most important classes of polyelectrolytes.Amino functionalized polymers aggregate to spherical, cylindrical, tubular and vesicular phases in selective solvent spontaneously. Such aggregations can be used as templates for making nano-materials, immobilization matrices for enzymes and cells, and tissue engineering, and applicated in drug delivery such as vesicles possessing nano-sized hollow cubages.We summarize the amino group properties; structures, synthesis and industrial applications of cationic polyelectrolyte; characteristics and aggregation of polyelectrolyte solution. In this paper, we study on the synthesis methods, conformation and self-assembly behavior of amino functional cationic homo-or block polyelectrolytes. We try to find out the relationship between the aggregation structures and self-assembly condition, by which to analyses the self-assembly mechanism and control the aggregation.(1) A water-soluble monomer methacrylamido-pentylamine hydrochloride (MAAPA) was synthesized. The block copolymers were prepared by free radical polymerization using macroinitiator bis[methoxy poly(ethylene glycol) ethyl]4,4'-(diazene-1,2-diyl)bis(4-cyano-pentanoate)(mPEG-ACVA) as the initiator. The structure and molecular weight of polymers were characterized by1H-NMR and GPC-MALLS. Aggregation behavior of the polymer in aqueous solution was investigated by dynamic light scattering (DLS), TEM and Resonance Light Scattering (RLS) spectra. The experimental results show that the fluorescence intensity of the aggregates reduces and the size of the aggregates increases due to the amino groups with increasing solution pH. It was demonstrated that polyelectrolyte having a pH-responsive polyamine segment in water in prompt response to pH. Also the NaCl concentration could effect the size of the aggregates.(2) A water-soluble monomer N1-(4-vinylbenzyl)-pentane-1,5-diamine dihydrochloride (VBPDA)(with cadaverine salts) was synthesized. The polymers with cadaverine side groups were prepared by free radical polymerization using4',4'-azobis(4-cyanovaleric acid)(ACVA) as the initiator. The structure and molecular weight of polymers were characterized by FTIR,1H-NMR and GPC-MALLS. Aggregation behavior of the polymer in aqueous solution was investigated by dynamic light scattering (DLS), UV-spectrophotometer, RLS and fluorescence spectra. The experimental results show that the fluorescence intensity of the aggregates reduces and the size of the aggregates increases due to the cadaverine side groups with increasing solution pH. It was demonstrated that polyelectrolyte having a pH-responsive polyamine segment in water in prompt response to pH and the sizes of aggregates are in the range of23to406nm, increasing with the increase of pH.(3) A new pH-responsive diblock copolymer, methoxy poly (ethylene glycol)-b-poly[N1-(4-vinylbenzyl) pentane-1,5-diamine dihydrochloride](mPEG-b-PVBPDA). The monomer with cadaverine side group (N1-(4-vinylbenzyl) pentane-1,5-diamine dihydrochloride, VBPDA) and macro-initiator (mPEG-ACVA) were synthesized, respectively, and mPEG-b-PVBPDA was then obtained by free radical polymerization. The synthesis of mPEG-b-PVBPDA was confirmed by FTIR,1H NMR and GPC-MALLS measurements. At low pH, it is hydrophilic due to the protonation of the amine groups. With increasing pH, deprotonation occurs and the hydrophobicity of PVBPDA block increases. This molecular feature leads to interesting aggregation behavior of mPEG-b-PVBPDA in aqueous solutions at different pH as revealed by DLS measurements, TEM observations; RLS and fluorescence spectrometry. This polymer was further subjected to gene delivery evalutions and promising DNA transfection capacity has been found.In comparison, comb-like copolymers, consisting of the same hydrophobic PVBPDA backbone at high-pH, albeit with non-interaction hydrophilic mPEG polymer side chain, could self-assemble only into hollow nanoparticles of single-wall in aqueous media. Moreover, the copolymer aggregates exhibit a reversible change in fluorescence intensity in aqueous media within a pH range of2.6to10.8. Finally, the transfection activity of mPEG-b-PVBPDA as novel carrier for synthetic DNA in gene therapy was evaluated.(4) A novel water-soluble block polypseudorotaxanes is synthesized in water from cucurbituril (CB[6]) and a diblock copolymer, methoxy poly (ethylene-glycol)-b-poly[N1-(4-vinylbenzyl) pentane-1,5-diaminedihydrochloride](mPEG-b-PVBPDA), by simple stirring at room temperature. Driven by hydrophobic/hydrophobic and charge/dipole interactions, CB[6] beads are localized on pentamethylene units in side chains of3as found by NMR studies. The degree of threading, i.e., the average number of CB[6] beads per repeat recognition unit of mPEG-b-PVBPDA (denoted as q/n hereafter), can be controlled from0.2to1.0by varying the amount of CB[6] added. This molecular feature leads to interesting aggregation behavior of the polypseudorotaxanes in aqueous solutions at different q/n as revealed by DLS measurements, TEM observations, UV-vis and fluorescence spectrometry. The average hydrodynamic radius (Rh), the intensity of UV-vis absorption band,RLS and the fluorescence intensity (If) of the block polypseudorotaxanes in solution increase with the increasing of CB[6] threaded.The degree of CB[6] threaded can be controlled from0.25to1.0. The polypseudorotaxanes in aqueous solution have more rigid chain conformation because of the threaded CB[6]. The Rh, the intensity of UV-vis absorption band and If of the polypseudorotaxanes increases with the increasing amount of CB[6] threaded.