Synthesis And Properties Of Imidazolium-Functionalized Ionic Polvmers And Their Nanocomplexes

A series of positively charged imidazolium-functionalized ionic polyurethanes (IPUs) were prepared in one-step polymerization process by polymerization of pre-synthesized short-chain imidazolium-based ionic diol, polyethylene glycols (PEGs) with different molecular weights as long-chain diols, and toluylene-2,4-diisocyanate(TDI). The structures of IPUs are confirmed by'H NMR analysis, and the TGA measurement indicates that the IPUs have high degradation temperature. By the electrostatic interaction between positively charged IPUs and the negatively charged aqueous CdTe quantum dots (QDs), fluorescent nanocrystal-polymer composites CdTe-IPU can be prepared conveniently. UV-vis absorption and photoluminescence (PL) spectra indicate the photochemical stability and strong fluorescent emission of CdTe-IPU composites. The TEM photographs show that the QDs in composites are uniform and monodisperse. The obtained nanocomposites are powder or elastomers with good film building. The casted CdTe-IPU films are transparent under visible light, and the colors of the composites and their films are vivid under a UV lamp.Fe3O4magnetic nanoparticles with mean diameter of about6nm coated by PEG4000were prepared by a precipitation method with ferric chloride, ferrous sulfate as starting materials and ammonia for alkalinizing, and the Fe3O4-PEG4000magnetic nanoparticles obtained were further modified by citric acid through ultrasonic treatment. Afterwards, NH2end group surface functionalized Fe3O4magnetic nanoparticles Fe3O4@SiO2-NH2were prepared through Stober method using silane coupling agent. Further, positively charged ionic polyurethane (IPU) was grafted onto the surface of Fe3O4@SiO2nanoparticles by polymerization of NH2end group, presynthesized ionic diol, PEG200and toluylene-2,4-diisocyanate (TDI). Finally, Fe3O4/CdTe/polyurethane (Fe3O4/CdTe/IPU) nanocomposites were prepared by electrostatic interaction of positively charged IPU and thioglycolic acid coated CdTe quantum dots(QDs). The structure Fe3O4/CdTe/IPU nanocomposites was characterized and verified by XRD, FT-IR, TGA, TEM, VSM, UV, PL analyses. The hysteresis loops proved the superparamagnetic properties of the as-prepared magnetic nanoparticles and nanocomposites. The UV and PL spectra suggested the nanocomposites were composed of the properties of the QDs and the UV irradiation images showed that the QDs moved and aggregated with magnetic nanoparticles in the magnetic field.The NCO-terminated positively charged ionic polyurethane (NCO-IPU) precursor was grafted onto the surface of Graphene oxide (GO) by reaction of-NCO with-OH/-COOH of the GO surface. The GO/IPU composites were then reduced by hydrazine monohydrate into Graphene (GE)/IPU composites. The structure of GO/IPU and GE/IPU composites was characterized and verified by FT-IR, UV-Vis. XRD, TGA and AFM analyses. Further, CdTe/GE/IPU and CdTe/GE/IPU nanocomposites were prepared by electrostatic interaction of positively charged IPU and thioglycolic acid coated CdTe quantum dots(QDs). UV-vis absorption and photoluminescence (PL) spectra indicate the photochemical stability and fluorescent emission of CdTe/GE/IPU and CdTe/GE/IPU composites. The TEM photographs show that the QDs incorporated on the surface of the GO/IPU or GE/IPU sheets are uniform and monodisperse.Side-chain imidazolium-functionalized random copolymer P(MMEIM+Cl--co-St) was synthesized by free-radical copolymerization of l-methyl-3-(2-methacryloyloxy ethyl) imidazolium chloride (MMEM+Cl-) and styrene (St) with AIBN as initiator. The structure of random copolymer obtained has been characterized and verified by FT-IR.1H NMR. and GPC analyses. By the electrostatic interaction between positively charged imidazolium-functionalized P(MMEIM+Cl--co-St) and the negatively charged aqueous CdTe quantum dots (QDs), fluorescent nanocrystal-polymer composites CdTe/P(MMEIM+Cl--co-St) can be prepared conveniently. UV-vis absorption and photoluminescence (PL) spectra indicated the photochemical stability and strong fluorescent emission of CdTe/P(MMEIM+Cl--co-St) composites. The transmission electron microscopy (TEM) photograph showed that the CdTe QDs in composites are monodisperse and uniform and no significant surface deterioration or aggregation of the QDs occurred during the CdTe/P(MMEIM+Cl--co-St) composite synthesis. Photographs of CHCl3solution of the as-synthesized CdTe/P(MMEIM+Cl--co-St) nanocomposites indicated that the nanocomposite solution is clear under normal light, and vivid with green-emitting under365nm UV light excitation.Main-chain imidazolium-functionalized amphiphilic block copolymers (PIL-b-PS) consisting of polyionic liquid (PIL) and polystyrene (PS) blocks have been firstly synthesized by condensation polymerization combined with nitroxide-mediated free radical polymerization (NMP). The di-functional imidazolium-based ionic liquid (1L) having both hydroxyl and ester end groups was synthesized through Michael addition between imidazole and methylacrylate (MA), and further quaternization by2-chloroethanol. The HTEMPO (4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy) terminated polyionic liquid (HTEMPO-PIL) as the hydrophilic block was prepared by condensation polymerization of di-functional imidazolium IL and HTEMPO at a certain ratio. The hydrophobic PS block was synthesized by controlled radical polymerization of styrene using HTEMPO-PIL through NMP, resulting PIL-b-PS block copolymers. The structure of block copolymers obtained has been characterized and verified by FT-IR,1H NMR, and SEC analyses. In addition, the morphology and size of the micelles formed by PIL-b-PS block copolymers in water were investigated by TEM and DLS.