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1.
A metal-chelating superabsorbent hydrogel based on poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylic acid-co-acrylamide) grafted onto sodium alginate backbone, NaAlg-g-poly(AMPS-co-AA-co-AM) is prepared under microwave irradiation. The Taguchi method is used for the optimization of synthetic parameters of the hydrogel based on water absorbency. The Taguchi L9 (34) orthogonal array is chosen for experimental design. Mass concentrations of crosslinker MBA \(C_{\text{MBA}}\) initiator KPS \(C_{\text{KPS}}\), sodium alginate \(C_{\text{NaAlg}}\) and mass ratio of monomers \(C_{\text{AM/AA/AMPS}}\) are chosen as four factors. The analysis of variance of the test results indicates the following optimal conditions: 0.8 g L?1 of MBA, 0.9 g L?1 of KPS, 8 g L?1 of NaAlg and \(R_{\text{AM/AA/AMPS}}\) equals to 1:1.1:1.1. The maximum water absorbency of the optimized final hydrogel is found to be 822 g g?1. The relative thermal stability of the optimized hydrogel in comparison with sodium alginate is demonstrated via thermogravimetric analysis. The prepared hydrogel is characterized by FTIR spectroscopy and scanning electron microscopy. The influence of the environmental parameters on water absorbency such as the pH and the ionic force is also investigated. The optimized hydrogel is used as adsorbent for hazardous heavy metal ions Pb(II), Cd(II), Ni(II) and Cu(II) and their competitive adsorption is also discussed. Isotherm of adsorption and effect of pH, adsorption dosage and recyclability are investigated. The results show that the maximum adsorption capacities of lead and cadmium ions on the hydrogel are 628.93 and 456.62 mg g?1, respectively. The adsorption is well described by Langmuir isotherm model. The hydrogel is also utilized for the loading of potassium nitrate as an active agrochemical agent and the release of this active agent has also been investigated.  相似文献   

2.
A well-defined thermo- and pH-responsive ABC-type triblock copolymer monomethoxy poly(ethylene glycol)-b-poly(2-(2-methoxyethoxy) ethyl methacrylate-co-N-hydroxymethyl acrylamide)-b-poly(2-(diethylamino) ethyl methacrylate), mPEG-b-P(MEO2MA-co-HMAM)-b-PDEAEMA, was synthesized by reversible addition-fragmentation chain transfer polymerization (RAFT). The ABC-type triblock copolymer was endowed thermo- and pH-responsive, corresponding to the thermosensitive properties of P(MEO2MA-co-HMAM) and pH-responsive properties PDEAEMA segments, respectively. The thermo- and pH-responsive properties of copolymer aqueous solutions were studied by UV transmittance measurements, dynamic light scattering (DLS), transmission electron microscopy (TEM). The results showed that the N-hydroxymethyl acrylamide (HMAM) content in triblock copolymer affected the lower critical solution temperature (LCST) of the triblock copolymer aqueous solution. The copolymer self-assembled into core-shell micelles, with the thermoresponsive P(MEO2MA-co-HMAM) block and the hydrophilic PEG block as the shell, the hydrophobic PDEAEMA block as the core, in alkaline solution at room temperature. While in acidic media, when the temperature above the lower critical solution temperature (LCST) of the triblock copolymer aqueous solution, the copolymer self-assembled into P(MEO2MA-co-HMAM)-core micelles with mixed hydrophilic PEG and pH-responsive PDEAEMA coronas. Sol-gel transition temperature (Tsol-gel) for the triblock copolymer determined by vial inversion test further indicated that it is dependent on the concentration of the triblock copolymers and solution pH. Copolymer hydrogel loaded with bovine serum albumin (BSA) were used for the sustained release study. The results indicated that the hydrogel was a promising candidate for controlling protein drug delivery.  相似文献   

3.
A series of well-defined novel amphiphilic temperature-responsive graft copolymers containing PCL analogues P(αClεCL-co-εCL) as the hydrophobic backbone, and the hydrophilic side-chain PEG analogues P(MEO2MA-co-OEGMA), designated as P(αClεCL-co-εCL)-g-P(MEO2MA-co-OEGMA) have been prepared via a combination of ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). The composition and structure of these copolymers were characterized by 1H NMR and GPC analyses. The self-assembly behaviors of these amphiphilic graft copolymers were investigated by UV transmittance, a fluorescence probe method, dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses. The results showed that the graft copolymers exhibited the good solubility in water, and was given the low critical temperature (LCST) at 35(±1) °C, which closed to human physiological temperature. The critical micelle concentrations (CMC) of P(αClεCL-co-εCL)-g-P(MEO2MA-co-OEGMA) in aqueous solution were investigated to be 2.0 × 10?3, 9.1 × 10?4 and 1.5 × 10?3 mg·mL?1, respectively. The copolymer could self-assemble into sphere-like aggregates in aqueous solution with diverse sizes when changing the environmental temperature. The vial inversion test demonstrated that the graft copolymers could trigger the sol-gel transition which also depended on the temperature.  相似文献   

4.
In this work, a novel chitosan/P(2-acrylamido-2-methyl-1-propanesulfonic acid-co-acrylic amide) (CS/P(AMPS-co-AM)) hydrogel was successfully prepared by a simple one-step method using glow-discharge-electrolysis plasma (GDEP) initiated copolymerization, in which N,N′-methylenebisacrylamide was used as a cross-linking agent. A copolymerization mechanism of AMPS and AM onto CS initiated by GDEP was proposed. The structure, thermal stability and morphology of CS/P(AMPS-co-AM) hydrogel were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), TG/DTG, and scanning electron microscope (SEM). This hydrogel was employed as an absorbent for the removal of methylene blue (MB) and malachite green (MG) from aqueous solutions. The effects of pH, contact time and equilibrium concentration on the dye adsorption were investigated batchwise. FTIR and XRD indicated that AM and AMPS were grafted onto the CS backbone successfully, forming copolymer. TG/DTG suggested that grafted AMPS and AM onto CS could change the thermal stability of the CS. SEM showed a unique three-dimensional porous structure for the CS/P(AMPS-co-AM) hydrogel. The optimum pH for the removal of cationic dyes was 5.8, and time of adsorption equilibrium was achieved in 90 min. The CS/P(AMPS-co-AM) hydrogel exhibited a very high adsorption potential, and its adsorption capacities calculated based on the Langmuir isotherm for MB and MG were 1,538.5 and 917.4 mg g?1, respectively. The dye adsorption data fitted well to the pseudo-second-order model and Langmuir model at 25 °C with pH 5.8.  相似文献   

5.
A novel series of copolymer hydrogels of 2-(dimethylamino)ethylacrylate (DMAEA)/2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) were prepared by solution free radical polymerization at different feed monomer mol ratios. The monomer reactivity ratios were determined by Kelen–Tüdös method. According to that, the monomer reactivity ratios for poly(DMAEA-co-AMPS) were r1 = 0.125 and r2 = 2.85, (r1 × r2 = 0.356). The effect of reaction parameters, including the concentration of cross-linking reagent N,N′-methylene-bis-acrylamide (MBA) and initiator ammonium persulfate (APS), the monomer concentration, pH, temperature, salt solutions, and solvent polarity on the water absorption have been also studied. The hydrogels achieved water-absorption values of 430 g of water/g of xerogel for the copolymer 1:2 richest in AMPS moiety. This copolymer is also very stable to the temperature effect. The optimum pH for the copolymers is 7. Aqueous solutions of the copolymers showed lower critical solution temperature behaviour (LCST). The phase transition temperatures of aqueous solutions of these copolymer increased with increasing of hydrophilic AMPS unit content in the copolymers. The glass transition temperature (Tg) of hydrogels showed a decrease by increasing of comonomer DMAEA content.  相似文献   

6.
A bifunctional comonomer β-methylhydrogen itaconate was synthesized to prepare high molecular weight poly [acrylonitrile-co-(β-methylhydrogen itaconate)] [P (AN-co-MHI)] by mixed solvents polymerization, which was used as carbon fiber precursor instead of acrylonitrile terpolymers. The effect of dimethyl sulfoxide (DMSO)/deionized water ratios on the polymerization, structure and stabilization of P (AN-co-MHI) was studied by elemental analysis, UV-Visible Spectroscopy, fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The highest viscosity-average molecular weight (76.72 × 104 g/mol) of P(AN-co-MHI) was obtained in the mixed solvents of DMSO/deionized water = 10/90 (wt/wt) due to the zero chain transfer constant of deionized water for radical ~ ~ ~AN·, which is 10 times larger than that of P(AN-co-MHI) copolymers prepared in DMSO solution polymerization under the same conditions and is beneficial to improving the tensile strength of resulting carbon fiber. The composition of P(AN-co-MHI) was controlled by the ratio of DMSO/deionized water in the mixed solvents, it is attributed to the changes of AN/MHI ratio taking part in the polymerization reactions, which is caused by the different solubility of AN in the mixed solvents. From elemental analysis and FTIR studies, it can be found out that the content of MHI in P(AN-co-MHI) copolymer becomes larger with the increase of DMSO content in the mixed solvents. The FTIR, XRD and DSC results show that the stabilization of P(AN-co-MHI) copolymer was significantly improved by MHI compared with PAN homopolymer and poly (acrlonitrile-methyl acrylate-acrylic acid) terpolymer, such as larger extent of stabilization, lower initiation temperature and smaller E a of cyclization, which is beneficial to preparing high performance carbon fiber.  相似文献   

7.
Polyamide 6 (PA 6) is an important thermoplastic with excellent strength, stiffness, and good chemical resistance. The notch sensitivity and low notch impact toughness of PA 6, however, limit its application. A core-shell structured polyacrylic modifier, poly(n-butyl acrylate)/poly(methyl methacrylate-co-methacrylic acid) modifier (PBM-co-MAA), was used to toughen PA 6. To study the effect of PBM-co-MAA particles on the toughness of PA 6, various contents of poly(BA) in PBM-co-MAA latexes of 300 nm were synthesized by seed emulsion polymerization. The results showed that polymerization had an instantaneous conversion higher than 95 wt% and an overall conversion higher than 97 wt%. The PBM-co-MAA particles had a clear core–shell structure confirmed by transmission electron microscope (TEM). The mechanical properties of PA 6/PBM-co-MAA blends showed that the notch impact strength of PA 6/PBM-co-MAA blends with 85 wt% poly(BA) and 0.5 wt% MAA in PBM-co-MAA was nearly six times greater than that of pure PA 6, being consistent with the scanning electron microscope (SEM) observations on the fractured surfaces. The notch impact strengths of PA 6/PBM-co-MAA blends were also better than that of PA 6/PBM blend, which did not contain MAA functional group in the modifier. Dynamic mechanical analysis (DMA) results showed improved compatibility between PA 6 matrix and core-shell toughening modifier, which should contain a functional group in the shell layer and a suitable core rubbery content to toughen PA 6 effectively.  相似文献   

8.
Thermo- and pH-responsive N-isopropylacrylamide (NIPAM) nanogels can be obtained by copolymerization of acrylic acid (AA) comonomer through differential microemulsion polymerization. The effects of comonomer, cross-linker, surfactant contents, and water/oil ratio were preliminarily investigated by a 24 full factorial design in order to eliminate the insignificant parameters from the polymerization analysis. The smallest poly(NIPAM-co-AA) nanogel particles were 40 ± 1 nm in diameter with 6 wt% of solid content and 98% conversion without coagulation. The comonomer amounts controlled the morphologies and LCST of the poly(NIPAM-co-AA) nanogels. The hairy microgels of poly(NIPAM-co-AA) with a 10:90 mol ratio of AA/ NIPAM had a lower critical solution temperature (LCST) of 6 °C. With an increase in the AA amount to a 17 mol ratio, the LCST increased to 27 °C, resulting in core-shell morphology. The morphology of resultant nanogels was characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, and differential scanning calorimetry. Nuclear magnetic resonance spectroscopy was used to calculate the mole ratio of NIPAM and AA in resultant nanogels after dialysis. Both nanogel mole ratio and morphology effectively retained the cationic anti-cancer drug of methylene blue for several hours, an important basic requirement for a drug delivery system. Compared to core-shell microgels, a higher methylene blue release was obtained from the hairy microgels in simulated intestinal fluid.  相似文献   

9.
Novel bioengineering copolymers were synthesized by radical copolymerization of N-isopropylacrylamide (NIPA) and 3,4-2H-dihydropyran (DHP) with 2,2′-azobisisobutyronitrile as an initiator in acetone solution at 70 °C under nitrogen atmosphere. Structure, tacticity and compositons of the copolymers prepared in a wide range of monomer feed were confirmed by FTIR, 1H{13C} NMR-DEPT and elemental analyses. The monomer reactivity ratios (r 1 and r 2) were detected using known two methods: r 1 (NIPA)?=?1.25 and r 2?=?0.035 (DHP), and r 1 (NIPA) ?=?0.97 and r 2?=?0.022 (DHP) by Kelen-Tüdös and Jaacks methods, respectively. It was demonstrated that the studied monomer pair has a tendency to form H-bonding beween amide/ether groups through ?NH...O< complexation which played an important role in the stereoselective chain growth, and significant decrease of allyl degradative chain transfer reactions. This phenomenon is also confirmed by the observed relatively high molecular weights of copolymers (M v ). The synthesized water-soluble stimuli-responsive poly(NIPA-co-DHP)s exhibit thermal stability, higher glass-transition temperature, polyelectrolyte, pH- and temperature-sensitive behavior and can be attributed to the class of bioengineering functional copolymers useful for various bio- and gene-engineering, and drug delivery applications.  相似文献   

10.
The present study demonstrates the separation of a critical pair of conjugated linolenic acid (CLN) isomers—jacaric acid (JA; c8, t10, c12-18:3) and punicic acid (PA; c9, t11, c13-18:3)—on a 60-m conventional Supelcowax 10 column. The alkyl esters of different alcohols (C1–C8) of JA and PA were prepared and analyzed isothermally at 220, 230 and 240 °C. The adequacy of their separation was determined from the separation factors (α) and peak resolutions (R s). Acceptable resolution (R s = 1.01) of JA and PA was obtained with their 2-ethyl-1-hexyl ester derivatives at a column temperature of 230 °C. In addition, the Gibbs energy of transfer from solution to gas of the three double bonds \((\Delta_{\text{sln}}^{\text{g}} G_{\text{u}}\)) could be used to describe the interactions of the double bond with the stationary phase. Characterization of 2-ethyl-1-hexyl esters of Jacaranda mimosifolia seed oil at 230 °C demonstrates that the oil contains JA and α- and β-calendic acid as a CLN without the presence of PA. The results suggested that JA could be resolved from PA on a 60-m Supelcowax 10 column as the ethyl hexyl ester.  相似文献   

11.
Two groups of disymmetric Gemini imidazolium surfactants, [C14C4C m im]Br2 (m = 10, 12, 14) and [C m C4C n im]Br2 (m + n = 24, m = 12, 14, 16, 18) surfactants, were synthesized and their structures were confirmed by 1H NMR and ESI–MS spectroscopy. Their adsorption at the air/water interface, thermodynamic parameters and aggregation behavior were explored by means of surface tension, electrical conductivity and steady-state fluorescence. A series of surface activity parameters, including cmc, γ cmc, π cmc, pC 20, cmc/C 20, Γ max and A min, were obtained from surface tension measurements. The results revealed that the overall hydrophobic chain length (N c) for [C14C4C m im]Br2 and the disymmetry (m/n) for [C m C4C n im]Br2 had a significant effect on the surface activity. The cmc values decreased with an increase of N c or m/n. The thermodynamic parameters of micellization (ΔG m θ , ΔH m θ , ΔS m θ ) derived from the electrical conductivity indicated that the micellization process of [C14C4C m im]Br2 and [C m C4C n im]Br2 was entropy-driven at different temperatures, but the contribution of ΔH m θ to ΔG m θ was enhanced by increasing N c or m/n. The micropolarity and micellar aggregation number (N agg) were estimated by steady-state fluorescence measurements. The results showed that the surfactant with higher N c or m/n can form larger micelles, due to a tighter micellar structure.  相似文献   

12.
Mesoporous nickel oxide (NiO) nanoparticles were synthesized by the thermal decomposition reaction of Ni(NO3)2·9H2O using oxalic acid dihydrate as the mesoporous template reagent. The pore structure of nanocrystals could be controlled by the precursor to oxalic acid dihydrate molar ratio, thermal decomposition temperature and thermal decomposition time. The structural characteristic and textural properties of resultant nickel oxide nanocrytals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), N2 adsorption–desorption isotherm and temperature programmed reduction. The results showed that the most excellently mesoporous nickel oxide particles (m-Ni-1-4) with developed wormlike pores were prepared under the conditions of the mixed equimolar precursor and oxalic acid and calcined for 4 h at 400 °C. The specific surface area and pore volume of m-Ni-1-4 are 236 m2 g?1 and 0.42 cm3 g?1, respectively. Over m-Ni-1-4 at space velocity = 20,000 mL g?1 h?1, the conversions of toluene and formaldehyde achieved 90 % at 242 and 160 °C, respectively. It is concluded that the reactant thermal decomposition with oxalic acid assist is a key step to improve the mesoporous quality of the nickel oxide materials, the developed mesoporous architecture, high surface area, low temperature reducibility and coexistence of multiple oxidation state nickel species for the excellent catalytic performance of m-Ni-1-4.  相似文献   

13.
Culicoides biting midges (Diptera: Ceratopognidae) cause pain and distress through blood feeding, and transmit viruses that threaten both animal and human health worldwide. There are few effective tools for monitoring and control of biting midges, with semiochemical-based strategies offering the advantage of targeting host-seeking populations. In previous studies, we identified the host preference of multiple Culicoides species, including Culicoides impunctatus, as well as cattle-derived compounds that modulate the behavioral responses of C. nubeculosus under laboratory conditions. Here, we test the efficacy of these compounds, when released at different rates, in attracting C. impunctatus under field conditions in Southern Sweden. Traps releasing 1-octen-3-ol, decanal, phenol, 4-methylphenol or 3-propylphenol, when combined with carbon dioxide (CO2), captured significantly higher numbers of C. impunctatus compared to control traps baited with CO2 alone, with low release rates (0.1 mg h?1, 1 mg h?1) being generally more attractive. In contrast, traps releasing octanal or (E)-2-nonenal at 1 mg h?1 and 10 mg h?1 collected significantly lower numbers of C. impunctatus than control traps baited with CO2 only. Nonanal and 2-ethylhexanol did not affect the attraction of C. impunctatus when compared to CO2 alone at any of the release rates tested. The potential use of these semiochemicals as attractants and repellents for biting midge control is discussed.  相似文献   

14.
Hydroxyl terminated polylactide polymers with number of average molecular weights (M n ) varying from 1625 to 3459 g mol?1 were synthesized by ring opening bulk polymerization of lactide in the presence of zinc acetate being a potent catalyst. The use of 1,4 butanediol (BDO) initiator leads to hydroxyl terminated polylactides, thus excellent precursors for shape-memory biodegradable polyurethanes. Different reaction conditions employed for the synthesis of hydroxyl terminated polylactide polymers via activated monomer mechanism may result in differences in M n , percentage mass conversion and percentage degree of crystallinity (%χ c ) of the product. Influence of process parameters, i.e. catalyst concentration, initiator concentration, reaction temperature and time on characteristics of hydroxyl terminated polylactides was studied. These polymers were characterized by Nuclear Magnetic Resonance (1H-NMR) spectroscopy, Fourier transforms infrared (FTIR) spectroscopy, gel permeation chromatography (GPC) and X-ray diffraction (XRD) techniques. FTIR and 1H-NMR confirmed the formation of hydroxyl terminated polylactides. M n was determined by 1H-NMR, GPC and end group analysis. %χ c was calculated from XRD spectra. Maximum mass conversion, M n and %χ c were observed at 5 mol% SnOct2 and 5 mol% BDO concentration. At optimum temperature of 145 °C, these characteristics improved linearly with polymerization time up to 6 h and declined thereafter.  相似文献   

15.
Poly(N-isopropylmethacrylamide-co-methacrylic acid) [p(NipAam-Mac)] microgels were synthesized and used as microreactors to fabricate silver nanoparticles. Pure and hybrid microgels were characterized using Ultraviolet–Visible (UV/Vis) spectroscopy, Fourier transform infra-red (FTIR) spectroscopy and transmission electron microscopy (TEM). Catalytic activity of hybrid microgels and mechanism of catalysis by this system was explored using different reaction conditions. At the same temperature, apparent rate constant (kapp) was found to be varied from 0.0414 to 0.7852 min?1 by increasing the concentration of NaBH4 from 2.49 to 22.41 mM at constant concentration of substrate and catalyst. However upon extra increase in concentration of NaBH4 from 22.41 to 37.35 mM reduced the value of kapp to 0.2178 min?1. Likewise, the value of kapp was found to be increased from 0.1242 to 0.5495 min?1 with increasing the concentration of 4-nitrophenol [Para-nitrophenol (p-Np)] from 0.063 to 0.079 mM keeping other parameters constant. Further increase in concentration of p-Np caused decline in the value of kapp. Kinetic data reveals that catalytic reduction of p-Np obeys Langmuir–Hinshelwood mechanism and p-Np is converted to p-Ap on the surface of the silver nanoparticles passing through various reaction intermediates.  相似文献   

16.
Pectin-graft-poly(2-acrylamido-2-methyl-1-propane sulfonic acid) (Pec-g-PAMPS) gel was made in the form of beads by subjecting the solution containing pectin (Pec), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) and ammonium peroxodisulphate to microwave irradiation followed by ionic crosslinking in CaCl2 solution. Gel beads containing silver nanoparticles were also prepared by the same method but with the addition of silver nitrate and trisodium citrate solution prior to microwave irradiation. The synthesized Pec-g-PAMPS and its silver nanocomposite (Pec-g-PAMPS-Ag) gel beads were characterized using FTIR, TGA, XRD, SEM, EDS and TEM techniques. The effect of incorporation of Ag NPs on the biological activity of Pec-g-PAMPS was studied by zone inhibition method considering two bacterial strains namely E. coli and B. subtilis. The nanocomposite gel exhibited higher antibacterial activity compared to the parent gel, which was comparable with the standard drug, Streptomycin. The in vitro drug release profiles of the parent gel and its composite were analyzed using Ketoprofen (KF) to study the effect of incorporation of Ag NPs on the drug release behavior of the Pec-g-PAMPS. The presence of silver nanoparticles enhanced both swelling of the gel beads and the extent of drug release significantly.  相似文献   

17.
A series of nonylphenol-substituted alkyl sulfonates (C x NPAS, x = 8, 10, 12, 14, 16) with two hydrocarbon chains and two different hydrophilic groups has been synthesized from α-olefins and nonylphenol. The respective products have a “pseudo-gemini” surfactant structure. The structures of the C x NPAS have been characterized by IR, UV, 1H nuclear magnetic resonance, electrospray ionization mass spectrometry, and elemental analysis. The effects of carbon chain length of the obtained surfactants on properties such as the critical micelle concentrations (CMC) in aqueous solutions, surface tension at the CMC (γ CMC), and efficiency of adsorption at the water/air interface (pC 20) have been determined. The γ CMC of the surfactants first decreased and then increased with increasing length of the carbon chain x, and reached a minimum of 29.25 mN/m at x = 10, which is much lower than that of α-olefin sulfonate (AOS) (33.52 mN/m). The CMC decreased and pC 20 increased with increasing x. The introduction of the hydroxyl group is responsible for multiple molecular conformations at the water/air interface and leads to a greater molecular area A min and smaller Γmax than those of AOS.  相似文献   

18.
Synthesis and ion transport characterization of a new K+-ion conducting nano-composite polymer electrolytes (NCPEs): (1?x) [70PEO:30KBr] + x SiO2, where 0 < x < 20 wt%, are reported. The present NCPEs have been cast using a novel hot-press technique in place of the traditional solution cast method. The conventional solid polymer electrolyte (SPE) composition: (70PEO:30KBr), identified as the highest conducting composition at room temperature, has been used as first-phase host matrix and nano-size (~8 nm) particles of SiO2 as second-phase dispersoid. As a consequence of dispersal of SiO2 in SPE host, two orders of conductivity enhancement have been observed in NCPE composition: [95(70PEO:30KBr) + 5SiO2] and this has been referred to as optimum conducting composition (OCC). The polymer-salt/nano-filler SiO2 complexation and thermal properties characterization were done with the help of XRD, FTIR, SEM, DSC and TGA studies. The ion transport behavior in NCPEs have been discussed on the basis of experimental measurements on some basic ionic parameters, viz. conductivity (σ), ionic mobility (μ), mobile ion concentration (n), ionic transference number (t ion), etc. The temperature-dependent conductivity studies of NCPE OCC have been done and activation energy (E a) value was determined using log σ?1/T Arrhenius plot.  相似文献   

19.
We fabricated a novel vascular endothelial growth factor (VEGF)-loaded poly(lactic-co-glycolic acid) (PLGA)-nanoparticles (NPs)-embedded thermo-sensitive hydrogel in porcine bladder acellular matrix allograft (BAMA) system, which is designed for achieving a sustained release of VEGF protein, and embedding the protein carrier into the BAMA. We identified and optimized various formulations and process parameters to get the preferred particle size, entrapment, and polydispersibility of the VEGF-NPs, and incorporated the VEGF-NPs into the (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (Pluronic®) F127 to achieve the preferred VEGF-NPs thermo-sensitive gel system. Then the thermal behavior of the system was proven by in vitro and in vivo study, and the kinetic-sustained release profile of the system embedded in porcine bladder acellular matrix was investigated. Results indicated that the bioactivity of the encapsulated VEGF released from the NPs was reserved, and the VEGF-NPs thermo-sensitive gel system can achieve sol-gel transmission successfully at appropriate temperature. Furthermore, the system can create a satisfactory tissue-compatible environment and an effective VEGF-sustained release approach. In conclusion, a novel VEGF-loaded PLGA NPs-embedded thermo-sensitive hydrogel in porcine BAMA system is successfully prepared, to provide a promising way for deficient bladder reconstruction therapy.  相似文献   

20.
CO2 absorbents were prepared from polyethylene glycol and the polyamidines having N,N′-disubstituted amidine structure in the main chain synthesized through acid-catalyzed melt polycondensation of orthoesters and α,ω-diamines. The homogeneous binary mixtures with the polyamidines captured CO2 much more efficiently under CO2 flow than the one with polyethyleneimine. Furthermore, we investigated the CO2 capture and release by the binary mixtures in terms of effects of the volatility and the structure of polyamidines, temperature, and polyethylene glycol. Taking into consideration the results thus obtained, we conducted CO2 capture/release cycles with the CO2 capture step at 40 °C and with the CO2 releasing step at 80 °C in an alternating manner, thereby demonstrating the repeatability of CO2 capture and release by the binary system of the polyamidine and polyethylene glycol.  相似文献   

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