Synthesis, Characterization, and Solution Properties of a Novel Cross-Bridged Cyclam Manganese(IV) Complex Having Two Terminal Hydroxo Ligands (original) (raw)
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Journal of Polymer Science Part A: Polymer Chemistry, 1997
A novel carboxybetaine monomer, 6-(2-Acrylamido-2-methy lpropyldimethylammonio) hexanoate (AMPDAH), has been synthesized and copolymerized with acrylamide in an aqueous NaBr solution. The feed ratio of AM (Ml) : AMPDAB(M2) was varied from 98.5 :2.5 to O: 100 mol %. The polymerizations were carried out to 20-30% conversion. Copolymer compositions were determined with lSC NMR by integration of the amido carbonyl resonances. Reactivity ratios determined from the nonlinear least-squares method gave values of r] = 0.98 and r2 = 0.85, indicating random incorporation of the comonomers into the final copolymer. Molecular weights ranged from 7.3 to 4.7 X 10' g/mol. The volubility behavior of the copolymers is dependent on the mol % AMPDAH incorporated into the copolymers. When 25 mol % or more is incorporated, the copolymers are only swellable in aqueous media and attempts to solubilize these systems were unsuccessful. AMPDAH incorporation of 10 mol 70 or less resulted in copolymers soluble in aqueous media under a variety of conditions. The viscometric properties of copolymers with 10 mol To or less is reported as a function of pH and added electrolytes. At high pH in deionized water, the polyzwitterions show both inter-and intramolecular associations, which are disrupted by the addition of sodium chloride. In deionized water, as the pH of the aqueous medium is lowered, the copolymers exhibit dramatic increases in viscosity as the carboxylate groups are protonated and charge-charge repulsions of the quaternary ammonium groups induce polyelectrolyte behavior. ICI 1997tJohnWiley & Sons, Inc. Keywords: polyampholyte q polycation q zwitterionic q water soluble q carboxy betaine q acrylamide copolymers * To whom all correspondenceshould be addressed.
Synthesis and characterization of hydrophilic copolymers
International Journal of Biology, 2012
Two composition ratios of poly[N-isopropylacrylamide (NIPAAm)-co-2-hedroxy ethyl acrylate (2-HEA)] were prepared in ethanol/water mixtures (v/v, 1/1) using ammonium persulfate (APS) as initiator. The hydrophilic copolymers were characterized by DSC, TGA, GPC and SEM. The results showed that molecular weight, Tg, thermal stability increase with increase of NIPAAm in the copolymers. The increase of molecular weight is interpreted in terms of increasing the formation of primary radicals in high ratio of NIPAAm in the copolymer. SEM showed that the polymer became more hydrophilic with increasing the ratio of NIPAAm in the copolymer.
Biomedical Materials, 2010
The aim of this work was the synthesis and characterization of a novel poly(N-isopropylacrylamide)-based copolymer, with hydrolysis-dependent thermosensitivity, for bioengineering applications. For this purpose, N-isopropylacrylamide (NIPAAm) and 2-hydroxyethylmethacrylate-6-hydroxyhexanoate (HEMAHex) monomers were chosen. The poly(NIPAAm-co-HEMAHex) copolymer was synthesized by radical polymerization. The physicochemical, mechanical, functional and biological properties of the copolymer were investigated. The physicochemical characterization confirmed that the copolymerization was successfully carried out. In addition, the newly synthesized poly(NIPAAm-co-HEMAHex) copolymer showed temperature sensitivity, with a phase separation temperature under body temperature (at 23 • C). Fourier transform infrared spectroscopy and differential scanning calorimetry results after hydrolysis tests indicated that the incorporation of the HEMAHex ester groups provides the cleavage of the lateral chain, which leads to an increase in the hydrophilicity of the copolymer and, consequently, to an increase in the lower critical solution temperature (LCST) with time. Since the LCST increases above body temperature (up to 40.4 • C), the copolymer becomes soluble again and diffuses away. It was also demonstrated that the hydrolysis occurred on the peripheral ester bond of the lateral chain, with the release of 6-hydroxyhexanoic acid, whose bioresorbibility has been reported in the literature. Therefore, the properties of this copolymer are very interesting and make it particularly attractive for biomedical applications.
One-dimensional co-ordination polymer of aqua-bridged binuclear manganese(II) carboxylate
Inorganic Chemistry Communications, 2008
A simple route for a novel sulphur containing one-dimensional aqua-bridged carboxylate co-ordination polymer of manganese(II) that have structural resemblance to biological aqua-bridged manganese systems is described. The manganese(II) co-ordination polymer is derived from dicarboxylate of (4-carboxymethoxy-2,3-bis-4-methylphenylsulfanyl-naphthalene-1-yloxy)-acetic acid and complex has pyridine as ancillary ligand.
Polymer, 2001
The association in dilute aqueous solution of the nonionic surfactant t-octylphenoxy polyoxyethanol (Triton X-100) with hydrophobically modi®ed copolymers based on an N-isopropylacrylamide (NIPAM) backbone is presented. The NIPAM-based copolymers contain also N,N-[(dimethylamino)propyl] methacrylamide (MADAP), the content x of MADAP varying from 0 up to 25 mol%, completely alkylated with dodecylbromide or octadecylbromide. The highly hydrophobic copolymers are characterised by a compact conformation in aqueous solution, due to the formation of intrachain hydrophobic aggregates. Association with Triton X-100 leads to the destruction of these intrachain aggregates and to their replacement by mixed alkyl/surfactant ones, revealed macroscopically by a gradual viscosity increase upon addition of surfactant. Fluorescence probing studies and dialysis equilibrium experiments con®rmed that polymer/surfactant association starts in the vicinity of the critical micelle concentration (CMC) of Triton X-100.
Polymers
We have previously demonstrated that poly(N-cyanomethylacrylamide) (PCMAm) exhibits a typical upper-critical solution temperature (UCST)-type transition, as long as the molar mass of the polymer is limited, which was made possible through the use of reversible addition-fragmentation chain transfer (RAFT) radical polymerization. In this research article, we use for the first time N-cyanomethylacrylamide (CMAm) in a typical aqueous dispersion polymerization conducted in the presence of poly(N,N-dimethylacrylamide) (PDMAm) macroRAFT agents. After assessing that well-defined PDMAm-b-PCMAm diblock copolymers were formed through this aqueous synthesis pathway, we characterized in depth the colloidal stability, morphology and temperature-responsiveness of the dispersions, notably using cryo-transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and turbidimetry. The combined analyses revealed that stable nanometric spheres, worms an...
Sequential Association of Anionic/Thermosensitive Diblock Copolymers with Cationic Surfactants
Macromolecules, 2013
The synthesis and properties of double hydrophilic block copolymers (DHBCs) are explored in the present work. These copolymers, denoted PSSNa-b-PNIPAM or PSSNa-b-PDMAM, are composed by an anionic poly(sodium styrenesulfonate), PSSNa, block and a thermosensitive poly(N-isopropylacrylamide), PNIPAM, or a hydrophilic poly(N,N-dimethylacrylamide), PDMAM, block, respectively. Core−shell nanoparticles, with a solidlike hydrophobic PNIPAM core and a hydrophilic PSSNa shell, are stabilized in water upon heating the aqueous PSSNa-b-PNIPAM solutions above the lower critical solution temperature of PNIPAM. The association of the diblock copolymers with the cationic surfactant cetyltrimethylammonium bromide, CTAB, was investigated as a function of charge mixing ratio and temperature, through turbidimetry, dynamic light scattering, ζ-potential measurements, and 1 H NMR spectroscopy. It is shown that both blocks of the PSSNa-b-PNIPAM DHBCs are able to associate with CTAB. The association process is sequential; namely, the mixed PNIPAM/CTAB aggregates are formed only when the PSSNa/CTAB complexation has been completed.
Carbohydrate Polymers, 2013
Mono-6-(allyl amino)-ˇ-cyclodextrin (N-ˇ-CD) and mono-2-O-(allyl oxygen radicals-2-hydroxyl propyl)-ˇ-cyclodextrin (O-ˇ-CD) were copolymerized with acrylamide (AM), acrylic acid (AA), and 1-llyl-3-oil acyloxyimidazole-1-ammonion bramide (AOAB) initiated by redox initiation system in an aqueous medium. The AM/AA/AOAB/N-ˇ-CD and AM/AA/AOAB/O-ˇ-CD were prepared by adjusting the reactive conditions, such as initiator concentration, pH, temperature, and monomer ratios. The obtained copolymers were characterized by means of infrared (IR) spectroscopy, 1 H NMR spectroscopy, scanning electron microscope (SEM), rotational rheometer, intrinsic viscosity, salt resistance, core flood test, etc. The temperature-tolerance, shear-tolerance, salt-resistance and thickening function of these copolymers are improved remarkably compared with partially hydrolyzed polyacrylamide (HPAM). About 18.3% and 12.5% oil recovery could be enhanced by 2000 mg/L AM/AA/AOAB/N-ˇ-CD and AM/AA/AOAB/O-ˇ-CD comparing with water-flooding. In addition, the result of X-ray diffractometry (XRD) test showed that the solutions of obtained copolymers could remarkably reduce the crystalline interspace of sodium montmorillonite (from 18.9Å to 15.3Å).
Synthesis and aqueous solution properties of stimuli-responsive triblock copolymers
Soft Matter, 2007
Two series of poly(di(methylamino)ethyl methacrylate)-b-poly(di(ethylene glycol)methyl ether methacrylate)-b-poly(di(methylamino)ethyl methacrylate), pDMAEMA-b-pDEGMEMA-b-pDMAEMA, and poly(di(ethylamino)ethyl methacrylate)-b-poly(di(ethylene glycol)methyl ether methacrylate)-b-poly(di(ethylamino)ethyl methacrylate), pDEAEMA-b-pDEGMEMA-b-pDEAEMA, triblock copolymers have been synthesized using copper-mediated living radical polymerization. Kinetic studies showed that the polymerizations were controlled yielding copolymers with MWt similar to predicted values with narrow polydispersities. UV/Vis experiments in aqueous solution indicate that the incorporation of pDMAEMA hydrophilic segments into the pDEGMEMA polymeric chains causes an increase in the lower critical solution temperature (LCST). Conversely, the incorporation of pDEAEMA hydrophobic segments has the reverse effect. It has been demonstrated that the cloud points of the copolymers increase when blocks pDMAEMA and pDEAEMA are protonated. At acidic pH and above 35-40 uC, the pDEGMEMA inner blocks become insoluble and, consequently, upon contact with water they form micellar aggregates constituted of a pDEGMEMA hydrophobic core with a pDMAEMA or pDEAEMA hydrophilic shell. At pH = 8.3 and 25 uC, the pDMAEMA-b-pDEGMEMA-b-pDMAEMA triblock copolymers form ordered aggregates of larger size. In addition under these conditions, in aqueous solution the pDEGMEMA form aggregates of smaller size than those found in the case of copolymers with pDMAEMA. Surface-tension measurements suggest that homopolymers, as well as copolymers, are surface active. The pDEGMEMA polymers present low values of the critical aggregation concentration (cac), due to their amphiphilic properties. The combination of pDEGMEMA thermosensitive segments with pDMAEMA and pDEAEMA blocks sensitive to pH and temperature has given rise to the formation of intelligent materials with responses to both stimuli. Their behavior depends on the MWt and the composition of the copolymers.
Journal of Research Updates in Polymer Science, 2014
The study presents a set of copolymers synthesis based on N-isopropylacrylamide, 2-dimethylaminoethyl methacrylate and itaconic acid comonomers found in different gravimetric ratio, acquired through polymerization in water in the presence of ammonium persulfate as radical initiator. The purpose was to prepare polymeric structure with dual sensitivity to temperature and pH respectively, and able as well to ensure intramolecular strategies for coupling applications of inorganic or bioactive compounds. The polymers composition was confirmed by FTIR and 1 H-NMR spectra. The thermal stability of the polymeric compounds was evaluated, and SEM investigations of the polymer morphology are also presented. The polymers dispersions were characterized from the viewpoint of their hydrodynamic radius, zeta potential and conductivity.