Effect of Poly(Vinyl Alcohol) on the Size,Shape, and Rate of Silver Nanoparticles Formation

The kinetics of cetyltrimethylammonium bromide (CTAB) stabilized silver nanoparticles have been studied spectrophotometrically at 425 nm (λ_max of silver sol) in the absence and presence of water soluble polymer (poly(vinyl alcohol); PVA). Transmission electron microscopy (TEM), ultraviolet-visible spectroscopy, and viscosity measurements were used to determine the size, shape, and the size distribution of the silver nanoparticles. The reaction follows the same behavior with respect to [CTAB], [tri-sodium citrate], and [Ag⁺] in both the media indicating the silver nonoparticles were formed through the same reaction path. The sigmoid nature of the kinetic curves suggests an autocatalytic path in the growth of nanoparticles. The reaction rate is increased by increasing [CTAB]. The presence of PVA inhibits nucleation and retards the rate of particle growth, absorbance and size of the particles. Polymer-surfactant interactions were analyzed based on the viscosity of the reaction mixture.     

Effect of the polymer matrix on the formation of silver nanoparticles in polymer–silver salt complex membranes

When polymer–silver salt complex membranes were exposed to UV irradiation, the separation performances of both the permeance and selectivity for propylene–propane decreased, which was primarily attributed to the reduction of the silver ions in the membranes to silver nanoparticles. Here, the effect of the polymer matrix on the formation of silver nanoparticles in the polymer–silver salt complex membranes was investigated. This effect was assessed for the complexes of two kinds of silver salts (AgBF₄ and AgCF₃SO₃) with several polymeric ligands containing three different carbonyl groups, including poly(vinyl pyrrolidone) (PVP) with an amide group, poly(vinyl methyl ketone) (PVMK) with a ketone group, and poly(methyl methacrylate) (PMMA) with an ester group. UV–vis spectra and transmission electron microscopy (TEM) images clearly indicated that the reduction rate of the silver ions has the following order in the various polymer matrices: PVP > PVMK > PMMA, whereas the size and the distribution of the nanoparticles exhibited the reverse order. The tendency to form silver nanoparticles was explained in terms of the differences between the comparative strengths of the interactions of the silver ions with the different carbonyl oxygens in the matrices, as well as that of the silver ions with counteranions, which was characterized by X‐ray photoelectron spectroscopy (XPS) and FT‐Raman spectroscopy. It was concluded that when the concentration of free silver ions was low due to weak polymer–silver ion and strong silver ion–anion interactions, as found with PMMA, the reduction rate of silver ions to silver nanoparticles was slow. Therefore, the PMMA–silver complex membranes were less sensitive to decreases in separation performance upon UV irradiation than compared to the PVP membranes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1168–1178, 2006     

Diene‐based polymer nanoparticles: Preparation and direct catalytic latex hydrogenation

The diene‐based polymer nanoparticles represented by poly(butadiene‐co‐acrylonitrile) were prepared in the semibatch emulsion polymerization system using Gemini surfactant (GS) trimethylene‐1,3‐bis(dodecyldimethylammonium bromide) as the emulsifier. The nanoparticles within the range of 17–54 nm were achieved with narrow molecular weight and particle size distributions. A spherical morphology was observed for the produced nanoparticles. The effects of GS concentration on the particle size, molecular weight, polymerization conversion and solid content, and composition of copolymer were investigated. The semibatch process using monomeric and conventional surfactant sodium dodecyl sulfate (SDS) was compared. At the second stage of this study, the prepared unsaturated nanoparticles were employed as the substrates for the latex hydrogenation in the presence of Wilkinson's catalyst, that is, RhCl(P(C₆H₅)₃)₃. The effects of the particle size and catalyst concentration on the latex hydrogenation rate were investigated. The particle size is found to have a significant effect on the reaction rate. When the 17‐nm nanoparticles were used as the substrates, a high conversion of 95 mol % was obtained within 18 h using only 0.1 wt % RhCl(P(C₆H₅)₃)₃. The latex hydrogenation process was completely free of organic solvents. The present synthesis and following “green” hydrogenation process can be extended to latices made from semibatch emulsion containing other diene‐based polymers. This study shows great promise for decreasing the demanded quantity of expensive catalyst and eliminating the organic solvent in the hydrogenation process. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

The effects of ring substituents in aniline on the reactivity of PANI with hydrogen tetrachloroaurate and the dispersion of gold nanoparticles

As expected from theoretical predictions, the polymerization of aniline was affected by the substituent group on the benzene ring. The rate of the polymerization varied as poly(2‐chloroaniline) (PANICl) < < poly(2‐methylaniline) (PANIMe) < polyaniline (PANI). While the rate of polymerization was determined largely by electronic effects of the substituent groups, the reactivity of the polymers was determined by the steric effects. The order of the rate of reaction of the polymers with AuCl₄⁻ was PANIMe < PANICl < < PANI. The amount of Au incorporated into the polymer matrix followed a similar trend. However, the size of the gold nanoparticles did not differ greatly. Gold nanoparticles dispersed on PANICl and PANIMe were more stable in acidic media than those on PANI. Copyright © 2015 John Wiley & Sons, Ltd.     

Catalytic reduction of 4‐nitrophenol using silver nanoparticles‐engineered poly(N‐isopropylacrylamide‐co‐acrylamide) hybrid microgels

Nearly monodisperse poly(N ‐isopropylacrylamide‐co ‐acrylamide) [P(NIPAM‐co‐AAm)] microgels were synthesized using precipitation polymerization in aqueous medium. These microgels were used as microreactors to fabricate silver nanoparticles by chemical reduction of silver ions inside the polymer network. The pure and hybrid microgels were characterized using Fourier transform infrared and UV–visible spectroscopies, dynamic light scattering, X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry and transmission electron microscopy. Results revealed that spherical silver nanoparticles having diameter of 10–20 nm were successfully fabricated in the poly(N ‐isopropylacrylamide‐co ‐acrylamide) microgels with hydrodynamic diameter of 250 ± 50 nm. The uniformly loaded silver nanoparticles were found to be stable for long time due to donor–acceptor interaction between amide groups of polymer network and silver nanoparticles. Catalytic activity of the hybrid system was tested by choosing the catalytic reduction of 4‐nitrophenol as a model reaction under various conditions of catalyst dose and concentration of NaBH₄ at room temperature in aqueous medium to explore the catalytic process. The progress of the reaction was monitored using UV–visible spectrophotometry. The pseudo first‐order kinetic model was employed to evaluate the apparent rate constant of the reaction. It was found that the apparent rate constant increased with increasing catalyst dose due to an increase of surface area as a result of an increase in the number of nanoparticles.     

Preparation,surface morphology,and optical properties of indium(III) oxide nanoparticles by thermolysis of indium–poly(vinyl alcohol) coordination polymer

First report on the preparation of well-dispersed, indium(III) oxide (In₂O₃) nanoparticles with 22–35?nm size by polymer thermolysis is presented. Indium–poly(vinyl alcohol) (PVA) coordination polymer films were prepared by ‘solution casting technique’ from the homogeneous aqueous solution of coordination polymer prepared using PVA and indium(III) nitrate as starting materials; subsequently the films were calcined at 550?°C to yield In₂O₃ nanoparticles. Both indium–PVA coordination polymer that served as the precursor and the titled nanoparticles were characterized by Fourier transform-infrared spectroscopy, photoluminescence (PL), powder X-ray diffraction (XRD), transmission electron microscopy, and thermal analysis. Room temperature PL spectra of the prepared indium oxide nanoparticles showed intense blue emissions around 360, 410 and 430?nm, characteristic of indium oxide nanoparticles due to oxygen vacancies. The lower energy PL emission decreases with an increase of indium(III) content in the precursor. The size of the nanoparticles calculated from line broadening of XRD pattern (cubic; JCPDS: 06-0416) was found to be around 24?nm. The average particle size of the synthesized nanoparticles increased with metal ion content in the precursor coordination polymer.     

Characterization of modified styrene-co-2-acrylamido-2-methylpropane sulfonic acid magnetite nanoparticles

This work provides an insight into the effect of incorporating of magnetite nanoparticles on the rheology of fluids. In this respect, polymer-stabilized magnetite nanoparticles were obtained using sodium salt of poly (2-acrylamido-2-methylpropanesulfonate (PAMPS-Na). Monodisperse polymer coated magnetite nanoparticles Fe₃O₄/poly(styrene-AMPS) copolymer nanoparticles with diameters of 50–300 nm were prepared by radical polymerization in the presence of a ferrofluid coated with PAMPS-Na. The magnetic nanoparticles were easily separated in a magnetic field. The structure of the obtained magnetic nanoparticles was characterized by Fourier transform infrared spectroscopy (FTIR). The morphology and size of the magnetic nanoparticles were determined by transmission electron microscopy (TEM). FTIR and TEM revealed that the Fe₃O₄ nanoparticles were incorporated into the shells of poly(styrene-AMPS). Aqueous dispersed solutions of a charged hydrophobically modified Fe₃O₄/poly(styrene-AMPS) copolymer nanoparticles exhibit high viscosities even at low polymer concentrations (0.1 wt %), which is an interesting feature in connection with enhanced oil recovery. Effects of temperature and addition of sodium chloride on the viscosity properties of a semidilute dispersed solution of Fe₃O₄/poly(styrene-AMPS) copolymer nanoparticles are examined. The results indicated that Fe₃O₄/poly(styrene-AMPS) copolymer nanoparticles disclose strong interactions between magnetite and coated polymers of both PAMPS-Na and styrene-AMPS copolymers.     

Effect of magnetic nanoparticles on the thermal properties of some hydrogels

Magnetic hydrogels (ferrogels) based on poly(vinyl alcohol) (PVA) and poly(hydroxyethyl methacrylate) (PHEMA) with magnetite (Fe₃O₄) nanoparticles were prepared. PVA ferrogels were synthesised by submitting the aqueous solution of polymer and Fe₃O₄ to freezing-thawing (F-T) cycles yielding a physical gel. Different samples were prepared by varying (i) the concentration of PVA, (ii) the concentration of magnetite and (iii) the number of F-T cycles applied. PHEMA ferrogels were prepared by a crosslinking polymerization reaction in the presence of magnetite yielding chemical gels. Different samples were prepared by varying (i) the concentration of HEMA, (ii) the concentration of EGDMA and (iii) the concentration of magnetite nanoparticles. All ferrogel samples were first dried before been analysed in a thermogravimetric analyzer. The resulting thermograms showed that the concentration of magnetite nanoparticles does affect the thermal stability of either ferrogels system, a general improvement in comparison with PVA and PHEMA hydrogels, respectively, being observed. The apparent activation energy (E_a) of the thermal degradation for PVA ferrogels was evaluated and calculated applying the Flynn-Wall and the Kissinger methods. Values of apparent E_a increased with the content of Fe₃O₄ in the ferrogel sample.     

Polymer-nanoparticle composites composed of PEDOT:PSS and nanoparticles of Ag synthesised by laser ablation

Laser ablation of a solid target material in a liquid environment provides with an easy, straightforward and environmentally friendly method for nanoparticles synthesis as well as with the unique possibility of directly controlling the type of the nanoparticles surface ligands through the liquid choice. In this paper, laser ablation (10.4 ps, 1064 nm and 50 kHz) of a bulk silver target in deionized water, was carried out for nanoparticles synthesis. The synthesised nanoparticles are either pure Ag or A₂O₃ or a mixture of the two materials. Their size distribution follows log-normal function with a statistical median diameter of ≈5 nm. The nanoparticles colloidal solutions were directly mixed after synthesis, with the polymer solution poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) for the formation of polymer-nanoparticles nanocomposite. The nanoparticles readily form bonds with the sulphur atom of PEDOT which results in their uniform distribution within the polymer matrix as well as in a replacement by the nanoparticles of the PSS⁻ as the counteranions to the PEDOT⁺. These effects result in the reduction of the effective insulation of the polymer blend particles by the insulating PSS and furthermore in the electrical conductivity of the nanocomposite becoming higher (by ∼1.5 times) as compared with that of the pure polymer.     

The Relationship of Reaction Temperature,Tg and Rich‐Syndiotacticity of Poly(alkyl methacrylate)s in Modified Microemulsion Polymerization

Nanoscale poly(alkyl methacrylate)s including poly(methyl methacrylate), poly(ethyl methacrylate), poly(cyclohexyl methacrylate), poly(iso‐butyl methacrylate) and poly(benzyl methacrylate) were prepared by a modified microemulsion polymerization procedure. NMR analysis suggested that these poly(methacrylate)s samples were higher in syndiotactic content, lower in isotactic content and the glass transition temperatures (T_gs) of them were also higher than those reported in the literature. The tacticities of the poly(methacrylate)s, beside the restricted volume effect of nanoparticles during the modified microemulsion polymerization, were mainly influenced by the reaction temperature, the lower the reaction temperature, the higher the syndiotacticity of the products. The syndiotacticity of the product decreased obviously when the polymerization was carried out at a temperature far above the T_g of the resulting polymer. It was also shown that the tacticity of the polymer was affected by the monomer structure, a monomer with the bulkier alkyl side group would liable to result in a polymer with richer syndiotacticity. Possible mechanism of rich‐syndiotacticity was also discussed.     

Preparation of monodisperse nanoparticles containing poly(propylene imine)(NH2)32‐polystyrene

Polypropylenimine dendrimer (DAB‐Am‐32, generation 4.0) was converted into a macroinitiator DAB‐Am‐32‐Cl via reaction with 2‐chloropropionyl chloride. Monodisperse nanoparticles containing poly(propylene imine)(NH₂)₃₂‐polystyrene were prepared by emulsion atom transfer radical polymerization (ATRP) of styrene (St), using the DAB‐Am‐32‐Cl/CuCl/bpy as initiating system. The structure of macroinitiator was characterized by FTIR spectrum, ¹H NMR, and ¹³C NMR. The structure of poly(propylene imine)(NH₂)₃₂‐polystyrene was characterized by FT‐IR spectrum and ¹H NMR; the molecular weight and molecular weight distribution of poly(propylene imine)(NH₂)₃₂‐polystyrene were characterized by gel permeation chromatograph (GPC). The morphology, size and size distribution of the nanoparticles were characterized by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effects of monomer/macroinitiator ratio and surfactant concentration on the size and size distribution of the nanoparticles were investigated. It was found that the diameters of the nanoparticles were smaller than 100 nm (30–80 nm) and monodisperse; moreover, the particle size could be controlled by monomer/macroinitiator ratios and surfactant concentration. With the increasing of the ratio of St/DAB‐Am‐32‐Cl, the number‐average diameter (D_n), weight‐average diameter (D_w) were both increased gradually. With enhancing the surfactant concentration, the measured D_h of the nanoparticles decreased, while the polydispersity increased. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2892–2904, 2009     

Organic solvent‐free catalytic hydrogenation of diene‐based polymer nanoparticles in latex form. Part II. Kinetic analysis and mechanistic study

The central challenge that has limited the development of catalytic hydrogenation of diene‐based polymer latex (i.e., latex hydrogenation) in large‐scale production pertains to how to accomplish the optimal interplay of accelerating the hydrogenation rate, decreasing the required quantity of catalyst, and eliminating the need for an organic solvent. Here, we attempt to overcome this dilemma through decreasing the dimensions of the polymer substrate (such as below 20 nm) used in the hydrogenation process. Very small diene‐based polymer nanoparticles were synthesized and then used as the substrates for the subsequent latex hydrogenation. The effects of particle size, temperature, and catalyst concentration on the hydrogenation rate were fully investigated. An apparent first‐order kinetic model was proposed to describe the rate of hydrogen uptake with respect to the concentration of the olefinic substrate (C?C). Mass transfer of both the hydrogen and catalyst involved in this solid (polymer)–liquid (water)–gas (hydrogen) three‐phase latex system is discussed. The competitive coordination of the catalyst between the C?C and acrylonitrile units within the copolymer was elucidated. It was found that (1) using very small diene‐based polymer nanoparticles as the substrate, the hydrogenation rate of polymer latex can be increased vastly to achieve a high conversion of 95% while a quite low level of catalyst loading is required; (2) this latex hydrogenation process was completely free of organic solvent and no cross‐linking was found; (3) the mass transfer of hydrogen is not a rate‐determining step in the present hydrogenation reactions; (4) the catalyst was dispersed homogeneously within the polymer nanoparticles; (5) for the reaction that has reached about 95 mol % conversion, the kinetic study shows that the reaction is chemically controlled with an apparent activation energy of 100–110 kJ/mol; (6) the strong coordination of C[tbond]N to the catalytically active species RhH₂Cl(PPh₃)₂ imposed a negative effect on the hydrogenation activity. The present research provides a comprehensive study to appreciate the underlying chemistry of latex hydrogenation of diene‐based polymer nanoparticles and more importantly shows great promise toward the commercialization of a “green” catalytic hydrogenation operation of a diene‐based polymer latex in industry. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Thermoresponsive poly(ionic liquid): Controllable RAFT synthesis,thermoresponse, and application in dispersion RAFT polymerization

The thermoresponsive poly(ionic liquid) of poly[1‐(4‐vinylbenzyl)‐3‐methylimidozolium tetrafluoroborate] trithiocarbonate (P[VBMI][BF₄]‐TTC) showing the soluble‐to‐insoluble phase transition in the methanol/water mixture at the upper critical solution temperature (UCST) was synthesized by solution RAFT polymerization and the synthesized P[VBMI][BF₄]‐TTC was employed as macro‐RAFT agent to mediate the RAFT polymerization under dispersion condition to afford the thermoresponsive diblock copolymer nanoparticles of poly[1‐(4‐vinylbenzyl)‐3‐methylimidozolium tetrafluoroborate]‐b‐polystyrene (P[VBMI][BF₄]‐b‐PS). The controllable solution RAFT polymerization was achieved as indicated by the linearly increasing polymer molecular weight with the monomer conversion and the narrow molecular weight distribution. The P[VBMI][BF₄]‐TTC macro‐RAFT agent mediated dispersion polymerization afforded the P[VBMI][BF₄]‐b‐PS nanoparticles, the size of which was uncorrelated with the polymerization degree of the P[VBMI][BF₄] block. Several parameters including the polymerization degree, the polymer concentration and the water content in the solvent of the methanol/water mixture were found to be correlated with the UCST of the poly(ionic liquid). The synthesized poly(ionic liquid) is believed to be a new thermos‐responsive polymer and will be useful in material science. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 945–954     

Functionalization of carbon black nanoparticles with poly(vinylidene fluoride)

The surface of carbon black (CB) nanoparticles was functionalized with poly(vinylidene fluoride) (PVDF) either by trapping of macroradicals or by cycloaddition. PVDF with two iodine end groups (I‐PVDF‐I) obtained from iodine transfer polymerization in supercritical CO₂ was heated in the presence of CB and the C? I bond was cleaved resulting in a reaction between the macroradical and the CB surface. To allow for cycloaddition of PVDF to the CB surface for a number of polymers, the iodine end groups were replaced by azide end groups. In addition, microwave irradiation was applied to the functionalization. The influence of temperature, time, polymer concentration, and polymer molar mass on the functionalization reaction was examined. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Synthesis of highly cross-linked poly(diethylene glycol dimethacrylate) microparticles in supercritical carbon dioxide

Herein we report the synthesis of poly(diethylene glycol dimethacrylate), poly(DEGDMA), by free-radical heterogeneous polymerization in supercritical carbon dioxide (scCO₂), using a commercially available carboxylic acid end-capped perfluoropolyether oil (Krytox 157FSL) as stabiliser. The effect of initial concentration of stabiliser, monomer and initiator on the yield and morphology of the resulting polymer has been investigated. Krytox worked effectively as a stabiliser and discrete poly(DEGDMA) particles with diameters ranging from 1.28 to 2.08 μm and narrow particle size distribution were produced in supercritical carbon dioxide, in high yield and in short reaction times, without making use of harmful organic solvents.     

分散共聚法制备特殊形态高分子微球的研究

以聚乙二醇 (PEG)大分子单体为反应性稳定剂 ,在丙烯腈的分散共聚反应中添加少量苯乙烯以形成疏水性核 ,制备得到了亚微米级高分子微球 .透射电子显微镜研究表明 ,该高分子微球具有特异的形态结构 .同时研究了分散共聚体系中各种反应因素对微球形态和直径的影响 ,结果表明 ,苯乙烯单体的添加量、PEG大分子单体的浓度及分子量、混合溶剂的组成对微球直径和形态均有明显的影响 .X 射线光电子能谱 (XPS)研究结果表明 ,微球表面聚集有亲水性PEG链 ,核为疏水的聚 (丙烯腈 苯乙烯 ) ,即形成的特异形态的PEG接枝高分子微球亦为复合型结构     

Monodispersed PEG‐b‐PSt nanoparticles prepared by atom transfer radical emulsion polymerization under microwave irradiation

Atom transfer radical emulsion polymerization of styrene using PEG‐Cl as macroinitiator under microwave irradiation was successfully conducted and monodispersed nanoparticles were prepared. The PEG‐Cl macroinitiator was synthesized, and confirmed by FTIR spectrum. The structure of the PEG‐b‐PSt diblock copolymer was characterized by ¹H‐NMR and the number of styrene unit in the diblock copolymer was calculated. The morphology, size, and size distribution of the nanoparticles were characterized by transmission electron microscope (TEM) and photon correlation spectroscopy (PCS). The effects of the ratio of macroinitiator and monomer, the ratio of catalyst and macroinitiator on the size and size distribution of nanoparticles were investigated. It was found that the diameters of PEG‐b‐PSt nanoparticles prepared under microwave irradiation were smaller (<50 nm) and more monodispersed than those prepared with conventional heating. Moreover, with the increasing of the ratio of St/PEG‐Cl, the hydrodynamic diameters (D_h) of the nanoparticles increased and the poly index decreased, both D_h and poly index of the nanoparticles prepared under microwave irradiation were smaller then those prepared with conventional heating; as the concentration of catalyst increased, the D_h of the nanoparticles decreased and the poly index of the nanoparticles increased. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 481–488, 2008     

Nanoparticle Size and Concentration Dependence of the Electroactive Phase Content and Electrical and Optical Properties of Ag/Poly(vinylidene fluoride) Composites

This paper describes the processing of silver‐nanoparticle‐doped poly(vinylidene fluoride). The effects of the concentration and size of the filler on the electroactive phase of the polymer and the optical and electrical properties are discussed. Spherical silver nanoparticles incorporated into the poly(vinylidene fluoride) polymeric matrix induce nucleation of the electroactive γ phase. The electroactive phase content strongly depends on the content and size of the nanoparticles. In particular, there is a critical nanoparticle size, below which the filler losses its nucleation efficiency due to its small size relative to that of the polymer macromolecules. Furthermore, the presence of surface plasmon resonance absorption in the composites is observed, which once again shows a strong dependence on the concentration and size of the particles. The absorption is larger for higher concentrations, and for a given concentration increases with particle size. This behavior is correlated to the electrical response and is related to the extra bands and electrons provided by the nanoparticles in the large energy band gap of the polymer.     

离子聚合物微球负载钯催化甲酸分解产氢

催化甲酸分解产氢是氢气储存和氢能利用的重要途径。以对乙烯基吡啶和1,3,5-三(溴甲基)-2,4,6-三甲基苯为原料,通过季胺化和聚合,制备了树枝状离子聚合物微球。负载Pd纳米粒子后用于催化甲酸分解产氢。微球的离子交换性能、含N特性以及分子内部空穴使制备的Pd 纳米粒子具有高分散性、小尺寸、均一粒径和优化的电子结构。考察了甲酸浓度和反应温度对产氢速率的影响。结果表明,在50℃、甲酸浓度为1 M、甲酸与钯摩尔比为200、甲酸与甲酸钠摩尔比为3的优化反应条件下,甲酸完全分解时间为30 min。催化剂使用4次后活性无明显下降。     

Effect of Pluronic P103 Concentration on the Simple Synthesis of Ag and Au Nanoparticles and Their Application in Anatase-TiO2 Decoration for Its Use in Photocatalysis

Silver and gold nanoparticles were synthesized under environmentally-friendly reaction conditions by using a biodegradable copolymer and water as a solvent. The triblock copolymer Pluronic P103 was utilized as a stabilizing agent or soft template to produce Ag and Au nanoparticles (NPs) of different sizes. Moreover, in the synthesis of Au NPs, the polymer acted as a reducing agent, decreasing the number of reagents used and consequently the residues produced, hence, rendering the procedure less complicated. It was observed that as the concentration of the polymer increased, the size of the metallic NPs augmented as well. However, AgNPs and AuNPs prepared with 1 and 10 wt% Pluronic P103, respectively, showed a significant decrease in particle size due to the presence of polymeric soft templates. The hybrid materials (metal/polymer) were characterized by UV-Vis spectroscopy, DLS, and TEM. The pre-synthesized nanoparticles were employed to decorate anatase-TiO₂, and the composites were characterized by DRS, XRD, BET surface area measurements, the TEM technique with the EDS spectrum, and XPS spectroscopy to demonstrate NPs superficial incorporation. Finally, methylene blue was used as a probe molecule to evidence the effect of NPs decoration in its photocatalytic degradation. The results showed that the presence of the NPs positively affected methylene blue degradation, achieving 96% and 97% removal by utilizing TAg0.1 and TAu10, respectively, in comparison to bare anatase-TiO₂ (77%).