Graft Copolymerization of 2‐Acrylamido‐2‐methyl Propane Sulfonic Acid on Dimethyl Sulfoxide Pretreated Poly(Ethylene Terephthalate) Films Using Cerium Ammonium Nitrate as Initiator

Abstract

In this study, graft polymerization of 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) on poly(ethylene terephthalate) (PET) films using cerium ammonium nitrate (CeAN) as an initiator was investigated. Before the polymerization reaction was carried out, films were swelled in dimethyl sulfoxide (DMSO) at 140°C for 1 h. The effect of polymerization temperature, time, initiator, and monomer concentrations on the graft yield were investigated. It was observed that the graft yield was initially increased with increasing temperature, monomer, and initiator concentrations; and then decreased. Graft yield was found to increase with increasing polymerization time up to 5 h, then remain constant. The effects of monomer and initiator inclusions on the grafting yield were also examined. Optimum conditions for grafting were found to be [AMPS] = 1.0 M, [Ce⁴⁺] = 1.5 × 10^?2 M, T = 85°C and t = 5 h. The rate of grafting was found to be proportional to the 0.1 and 0.4 powers of monomer and initiator concentrations, respectively. The overall activation energy for the grafting was calculated to be 11.4 kcal mol^?1. The effect of grafting on PET film properties such as intrinsic viscosity and water absorption capacity were determined. The grafted PET films were characterized with FTIR spectroscopy and scanning electron microscopy (SEM).     

Thermo-responsive microfibrillar graft copolymer based on carboxymethylagarose and N-isopropylacrylamide

Carboxymethylation of agarose with ClCH₂COOH in 2-propanol, formamide or dimethyl sulfoxide were evaluated in order to obtain water soluble derivatives. Higher yield (86%) and degree of substitution of carboxymethylation in primary alcoholic groups (0.70) were obtained using dimethyl sulfoxide. Carboxymethylagarose-g-PNIPAAm copolymers were synthesized by free radical graft copolymerization using Ce⁴⁺ and S₂O₈²⁻/TEMED as initiators via conventional or microwave-assisted methods. Carboxymethyl derivatives and graft copolymers were characterized by FT-IR and NMR spectroscopies, elemental analysis, TGA and DSC and morphology analysis by SEM and AFM. High nitrogen content (9.7%) was found with Ce⁴⁺ by conventional method and the obtained analysis allowed to confirm the NIPAAm grafting on the carboxymethylagarose chain. Thermoresponsive materials have a low critical solution temperature between 32 and 34 °C. Thermal stability increased ca. 60% with PNIPAAm grafting. Surface analysis of copolymers reveals a microfibrillar type morphology with diameter of 4–6 μm. Synthesized glycoconjugates could find applications in bioactive compounds transport in biological systems.     

Réactions chimiques oscillantes. II. Comportement de la «période d'induction» dans les systémes BrO/Ce4+/Cyclohexanone et BrO/Ce4+/Cyclopentanone

Oscillating Chemical Reactions. 11. Behaviour of the “induction period” in the BrO /Ce⁴⁺/Cyclohexanon and BrO /Ce⁴⁺/Cyclopentanon systems

• (1) The addition of α-monobromoketone, one of the products of reaction of the BrO₃^?/Ce⁴⁺/Cyclohexanon (S1) and BrO₃^?/Ce⁴⁺/Cyclopentanon (S2) oscillating systems, decreases and even suppresses the induction period (τ_ind.) in the case of S2. Such is not the case with S1: τ_ind. increases and the oscillations can even be completely inhibited.
• (2) The order of addition of the reagents and the time lapse (t_adj.) preceding the addition of the last of them influences τ_ind., particularly when the last reagent added is Ce⁴⁺.
• (3) In our experimental conditions, the inhibition of the oscillatory phenomenon by Cl^? ions is definite only for | Cl^? | ≥ 5,0 · 10^?2M (S1) and |Cl^?| > 2,5 · 10^?3M (S2); for lower concentrations τ_ind. increases with | Cl^?|.

     

A High‐Valent Manganese(IV)–Oxo–Cerium(IV) Complex and Its Enhanced Oxidizing Reactivity

A mononuclear nonheme manganese(IV)–oxo complex binding the Ce⁴⁺ ion, [(dpaq)Mn^IV(O)]⁺–Ce⁴⁺ ( 1 ‐Ce⁴⁺), was synthesized by reacting [(dpaq)Mn^III(OH)]⁺ ( 2 ) with cerium ammonium nitrate (CAN). 1 ‐Ce⁴⁺ was characterized using various spectroscopic techniques, such as UV/Vis, EPR, CSI‐MS, resonance Raman, XANES, and EXAFS, showing an Mn?O bond distance of 1.69 Å with a resonance Raman band at 675 cm^?1. Electron‐transfer and oxygen atom transfer reactivities of 1 ‐Ce⁴⁺ were found to be greater than those of Mn^IV(O) intermediates binding redox‐inactive metal ions ( 1 ‐Mⁿ⁺). This study reports the first example of a redox‐active Ce⁴⁺ ion‐bound Mn^IV‐oxo complex and its spectroscopic characterization and chemical properties.     

Hairy polymeric nanocapsules with ph‐responsive shell and thermoresponsive brushes: Tunable permeability for controlled release of water‐soluble drugs

The hairy poly(methacrylic acid‐co‐divinylbenzene)‐g‐poly(N‐isopropylacrylamide) (P(MAA‐co‐DVB)‐g‐PNIPAm) nanocapsules with pH‐responsive P(MAA‐co‐DVB) inner shell and temperature‐responsive PNIPAm brushes were prepared by combined distillation–precipitation copolymerization and surface thiol‐ene click grafting reaction using 3‐(trimethoxysilyl)propyl methacrylate‐modified silica (SiO₂‐MPS) nanospheres as a sacrificial core material. The well‐defined PNIPAm was synthesized by a reversible addition fragmentation chain transfer (RAFT) polymerization. The chain end was converted to a thiol by chemical reduction. The PNIPAm was integrated into the nanocapsules via thiol‐ene click reaction. The surface thiol‐ene click reaction conduced to tunable grafting density of PNIPAm brushes. The grafting densities decreased from 0.70 chains nm^?2 to 0.15 chains nm^?2 with increasing the molecular weight of grafted PNIPAm chains. Using water soluble doxorubicin hydrochloride (DOX·HCl) as a model molecular, the tunable shell permeability of the nanocapsule was investigated in detail. The permeability constant can be tuned by controlling the thickness of the P(MAA‐co‐DVB) inner shell, the grafting density of PNIPAm brushes, and the environmental pH and temperature. The tunable shell permeability of these nanocapsules results in the release of the loaded guest molecules with manipulable releasing kinetics. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2202–2216     

Grafting onto wool. IV. Effect of amines upon ceric ion-initiated grafting of poly(methyl acrylate)

Grafting of poly(methyl acrylate) onto wool has been carried out in an aqueous medium at 45 ± 1°C by using ceric ammonium nitrate (CAN) in the presence of triethylamine, diethylamine, n-butylamine, triethanolamine, and N,N-dimethylaniline. The percentage of grafting varied with the nature and concentrations of the amines. Reactivity of the different amines toward grafting reactions followed the order: triethylamine > diethylamine > n-butylamine > triethanolamine ≥ N,N-dimethylaniline. In the presence of N,N-dimethylaniline grafting did not occur. An attempt has been made to explain the observed reactivity of Ce⁴⁺ in various amine systems in graft copolymerization reactions.     

Graft copolymerization of methyl methacrylate onto lignosulfonate by H2O2–Fe(II) redox system. I. Preparation and characterization of the graft copolymer

Graft copolymerization of methyl methacrylate onto lignosulfonate in aqueous medium was investigated. It was found that the H₂O₂–Fe(II) redox system is very effective for the grafting (E_a = 4.4 kcal/mole). The H₂O₂/Fe²⁺ ratio was the most important factor in the graft copolymerization and characteristics of the resultant graft copolymers. In most cases, polymerization for 100 min at 30°C was enough to obtain 80% conversion and 50–60% grafting efficiency. The resultant polymer mixture was subjected to extraction alternately with acetone and water, and the graft copolymer was isolated free from homopolymer and unreacted lignosulfonate. With increasing H₂O₂/Fe²⁺ ratio, the grafting ratio showed a maximum at 4, whereas the yield of graft copolymer and number of poly(methyl methacrylate) branches for every building unit of lignosulfonate increased up to a ratio of 4, both values, however, remaining constant above 4. The graft copolymer obtained for the case H₂O₂/Fe²⁺ = 4 consisted of one part of lignosulfonate and five parts of poly(methyl methacrylate). The number of branches in the graft copolymer was 6 × 10^?3/OCH³ or one every 167 guaiacyl nuclei.     

Synthesis of statistical glycidyl methacrylate‐n‐vinyl pyrrolidone copolymers and their reaction with naproxen

Free‐radical copolymerization of glycidyl methacrylate (GMA) with N‐vinylpyrrolidone (VPD) was carried out at 50 °C using 3.0 mol · L^?1 of N,N′‐dimethylformamide solution and 9.0 · 10^?3 mol · L^?1 of 2,2′‐azobisisobutyronitrile as an initiator. The modification reaction of GMA‐VPD copolymers with a model bioactive carboxylic acid, 6‐methoxy‐α‐methyl‐2‐naphthaleneacetic acid (naproxen), was studied in the homogeneous phase using basic catalysts. The influence of the type of catalyst and the GMA content was evaluated. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1192–1199, 2002     

Catalytic properties of transition metal salts immobilized on nanoporous silica polyamine composites II: hydrogenation

The transition metal compounds Pd(OAc)₂, RhCl₃·4H₂O and RuCl₃ · nH₂O were adsorbed onto the nanoporous silica polyamine composite (SPC) particles (150–250 µm), WP‐1 [poly(ethyleneimine) on amorphous silica], BP‐1 [poly(allylamine) on amorphous silica], WP‐2 (WP‐1 modified with chloroacetic acid) and BP‐2 (BP‐1 modified with chloroacetic acid). Inductively coupled plasma‐atomic emission spectrometry analysis of the dried samples after digestion indicated metal loadings of 0.4–1.2 mmol g^?1 except for RhCl₃·4H₂O on BP‐2 which showed a metal loading of only 0.1 mmol g^?1. The metal loaded composites were then screened as hydrogenation catalysts for the reduction of 1‐octene, 1‐decene, 1‐hexene and 1, 3‐cyclohexadiene at a hydrogen pressure of 5 atm in the temperature range of 50–90 °C. All 12 combinations of SPC and transition metal compound proved active for the reduction of the terminal olefins, but isomerization to internal alkenes was competitive in all cases. Under these conditions, selective hydrogenation of 1,3‐cyclohexadiene to cyclohexene was observed with some of the catalysts. Turnover frequencies were estimated for the hydrogenation reactions based on the metal loading and were in some cases comparable to more conventional heterogeneous hydrogenation catalysts. Examination of the catalysts before and after reaction with X‐ray photoelectron spectroscopy and transmission electron microscopy revealed that, in the cases of Pd(OAc)₂ on WP‐2, BP‐1 and BP‐2, conversion of the surface‐ligand bound metal ions to metal nano‐particles occurs. This was not the case for Pd(OAc)₂ on WP‐1 or for RuCl₃ · nH₂O and RhCl₃· 4H₂O on all four composites. The overall results are discussed in terms of differences in metal ion coordination modes for the composite transition‐metal combinations. Suggested ligand interactions are supported by solid state CPMAS ¹³C NMR analyses and by analogy with previous structural investigations of metal binding modes on these composite materials. Copyright © 2011 John Wiley & Sons, Ltd.     

[DBU‐H]+ and H2o as effective catalyst form for 2,3‐dihydropyrido[2,3‐d]pyrimidin‐4(1H)‐ones: A DFT Study

DFT investigations are carried out to explore the effective catalyst forms of DBU and H₂O and the mechanism for the formation of 2,3‐dihydropyrido[2,3‐d]‐pyrimidin‐4(1H)‐ones. Three main pathways are disclosed under unassisted, water‐catalyzed, DBU and water cocatalyzed conditions, which involves concerted nucleophilic addition and H‐transfer, concerted intramolecular cyclization and H‐transfer, and Dimroth rearrangement to form the product. The results indicated that the DBU and water cocatalyzed pathway is the most favored one as compared to the rest two pathways. The water donates one H to DBU and accepts H from 2‐amino‐nicotinonitrile ( 1 ), forming [DBU‐H]⁺‐H₂O as effective catalyst form in the proton migration transition state rather than [DBU‐H]⁺‐OH^?. The hydrogen bond between [DBU‐H]⁺···H₂O··· 1 ^? decreases the activation barrier of the rate‐determining step. Our calculated results open a new insight for the green catalyst model of DBU‐H₂O. © 2015 Wiley Periodicals, Inc.     

Photograft Copolymerization of Methyl Methacrylate on Wool Using Ce4+ -Oxalic Acid Redox Initiator in a Limited Aqueous System

Abstract

Photograft copolymerization of methyl methacrylate on reduced wool (reduction done by treatment with thioglycollic acid, TGA) was studied at nearly 30°C using a Ce⁴⁺ -oxalic acid redox initiator system in a limited aqueous system (2.7 mL water for 0.15 g wool). Reduction of wool for 16 h with 15% TGA solution produced optimum grafting effects. Percent grafting and grafting efficiency under different sets of conditions were studied and compared, and the mechanism of grafting discussed. Generation of grafting sites (radical centers) on reduced wool was more effective in the presence of light than in the dark. Percent grafting of 250–350% and grafting efficiency of 65-80% over a conversion range of 60–90% in 3–5 h were easily obtained.     

A Simple Synthetic Method of a 1,3,5‐Triazine UV Absorbent CGL‐479 and Its Characterization

As a novel ultraviolet (UV) absorbent with excellent performance in UVA section (320 ~ 400 nm), 2‐{2‐hydroxy‐4‐[(octyloxycarbonyl)ethylideneoxy]phenyl}‐4,6‐Bis(4‐biphenylyl)‐1,3,5‐triazine (CGL‐479) was synthesized in a simple method with a total yield of 45.3% in four steps. Its outstanding UV absorption capability (λ_max = 326 nm, ε_max = 4.15 × 10⁴ L?mol^?1?cm^?1), high thermostability [T₅ (the temperature of losing 5% in weight) = 385 °C], and compatibility with polymer materials make it a potential substitute of the traditional UV absorbents.     

A New Amperometric Biosensor Based on HRP/Nano-Au/L-Cysteine/Poly（o-Aminobenzoic acid）-Membrane-Modified Platinum Electrode for the Determination of Hydrogen Peroxide

The third generation amperometric biosensor for the determination of hydrogen peroxide （H2O2） has been described. For the fabrication of biosensor, o-aminobenzoic acid （oABA） was first electropolymerized on the surface of platinum （Pt） electrode as an electrostatic repulsion layer to reject interferences. Horseradish peroxidase （HRP） absorbed by nano-scaled particulate gold （nano-Au） was immobilized on the electrode modified with polymerized o-aminobenzoic acid （poABA） with L-cysteine as a linker to prepare a biosensor for the detection of H2O2. Amperometric detection of H2O2 was realized at a potential of ＋20 mV versus SCE. The resulting biosensor exhibited fast response, excellent reproducibility and sensibility, expanded linear range and low interferences. Temperature and pH dependence and stability of the sensor were investigated. The optimal sensor gave a linear response in the range of 2.99×10^-6 to 3.55×10^-3 mol·L^-1 to H2O2 with a sensibility of 0.0177 A·L^-1·mol^-1 and a detection limit （S/N = 3） of 4.3×10^-7 mol·L^-1. The biosensor demonstrated a 95% response within less than 10 s.     

Three New Thioantimonates(V): Solvothermal Syntheses and Crystal Structures of [M(chxn)3]3(SbS4)2·4H2O (M = Ni,Co) and [Co(dien)2][Co(tren)SbS4]2·4H2O

The three new thioantimonates(V) [Ni(chxn)₃]₃(SbS₄)₂·4H₂O ( I ), [Co(chxn)₃]₃(SbS₄)₂·4H₂O ( II ) (chxn is trans‐1,2‐diaminocyclohexane) and [Co(dien)₂][Co(tren)SbS₄]₂·4H₂O ( III ) (dien is diethylenetriamine and tren is tris(2‐aminoethyl)amine) were synthesized under solvothermal conditions. Compounds I and II are isostructural crystallizing in space group C2/c. The structures are composed of isolated [M(chxn)₃]²⁺ complexes (M = Ni, Co), [SbS₄]^3? anions and crystal water molecules. Short S···N/S···O/O···O separations indicate hydrogen bonding interactions between the different constituents. Compound III crystallizes in space group and is composed of [Co(dien)₂]²⁺ and [Co(tren)SbS₄]^? anions and crystal water molecules. In the cationic complex the Co²⁺ ion is in an octahedral environment of two dien ligands whereas in [Co(tren)SbS₄]^? the Co²⁺ ion is in a trigonal bipyramidal coordination of four N atoms of tren and one S atom of the [SbS₄]^3? anion, i.e., two different coordination polyhedra around Co²⁺ coexist in this compound. Like in the former compounds an extended hydrogen bonding network connects the complexes and the water molecules into a three‐dimensional network.     

A New Fluorescein Isothiocyanate-Piperidine Self-ordered Ring Phosphorescent Probe for the Determination of Trace Protein

The ? COOH in fluorescein isothiocyanate (FITC) reacted with ? NH? in piperidine (P) to form FITC‐P on the center of indentation of polyamide membrane (PAM) when drying for 2 min at (92±1)°C. Then, the FITC‐P diffused outward from the indentation center and formed the round SOR‐P‐FITC (containing the FITC‐P self‐ordered rings). Thus, multi‐FITC accumulated on SOR‐P‐FITC, leading to the enhancement of RTP signal on bio‐target, whose I_p increased 2.0 times compared with non‐generated SOR. When bovine serum albumin (BSA) was added to the center of SOR‐P‐FITC, ? NCS of FITC in SOR‐P‐FITC reacted with ? NH₂ of BSA to form SOR‐P‐FITC‐BSA, which caused the RTP signal of FITC to enhance sharply. The ΔI_p of the system was 3.4 times higher than that without β‐CD and 4.0 times higher than that without SOR‐P‐FITC formed. Its ΔI_p was linear to the content of BSA. Therefore, a new solid substrate‐room temperature phosphorimetry (SS‐RTP) for the determination of trace protein was established using SOR‐P‐FITC as a phosphorescent probe. Under the optimum condition, the linear range of this method was 0.040–16.0 ag·spot^?1 with a detection limit (LD) of 8.5 zg·spot^?1 (0.40 µL sample solution per spot, the corresponding concentration was 2.1×10^?17 g·mL^?1), and the regression equation of working curve was ΔI_p=3.848+4.240m_BSA (ag·spot^‐1), n=6, correlation coefficient (r) was 0.9993. This method with high sensitivity had been applied to determining the content of trace protein in the water samples, and the results coincided well with those obtained with pyrocatechol violet‐Mo(VI) method (P.V.M.M.). At the same time, the mechanism of SS‐RTP using SOR‐P‐FITC as a phosphorescent probe (SOR‐P‐FITC‐SS‐RTP) was discussed.     

阴极催化剂Sm1.5Sr0.5MO4 (M＝Ni, Co, Fe)在低温常压下合成氨

利用溶胶—凝胶法制备了复合氧化物Sm1.5Sr0.5MO4 (M＝Ni, Co, Fe)(SSM),并利用XRD和SEM等对样品进行表征。用Nafion膜作电解质、以SSM作为阴极、Ni-SDC金属陶瓷为阳极、银-铂网做集流体组成单电池,在温度为25℃～100℃的低温常压下以干燥氮气和湿的氢气为原料进行电化学合成氨气测定,同时研究了影响氨合成的关键因素,确定了合适的工作温度,实验结果表明,最高氨产率可达到1.05×10-8mol·s-1·cm-2。     

New Structure Type among Octahydrated Rare‐Earth Sulfates, β‐Ce2(SO4)3·8H2O,and a new Ce2(SO4)3·4H2O Polymorph

Syntheses, crystal structures and thermal behavior of two new hydrated cerium(III) sulfates are reported, Ce₂(SO₄)₃·4H₂O ( I ) and β‐Ce₂(SO₄)₃·8H₂O ( II ), both forming three‐dimensional networks. Compound I crystallizes in the space group P2₁/n. There are two non‐equivalent cerium atoms in the structure of I , one nine‐ and one ten‐fold coordinated to oxygen atoms. The cerium polyhedra are edge sharing, forming helically propagating chains, held together by sulfate groups. The structure is compact, all the sulfate groups are edge‐sharing with cerium polyhedra and one third of the oxygen atoms, belonging to sulfate groups, are in the S–Oμ₃–Ce₂ bonding mode. Compound II constitutes a new structure type among the octahydrated rare‐earth sulfates which belongs to the space group Pn. Each cerium atom is in contact with nine oxygen atoms, these belong to four water molecules, three corner sharing and one edge sharing sulfate groups. The crystal structure is built up by layers of [Ce(H₂O)₄(SO₄)]_nⁿ⁺ held together by doubly edge sharing sulfate groups. The dehydration of II is a three step process, forming Ce₂(SO₄)₃·5H₂O, Ce₂(SO₄)₃·4H₂O and Ce₂(SO₄)₃, respectively. During the oxidative decomposition of the anhydrous form, Ce₂(SO₄)₃, into the final product CeO₂, small amount of CeO(SO₄) as an intermediate species was detected.     

Highly branched acrylamide graft copolymer

Acrylamide graft copolymerization onto poly(3-O-methacryloyl D -glucose) (PMG) as a backbone was performed by the ceric ion method. The number of polyacrylamide (PAM) chains grafted was dependent upon the concentration ratio of the redox catalyst system at constant acid concentration and increased in proportion to the ceric ion concentration. A maximum number of grafts obtained, for example, was 29 onto PMG (DP = 244) under the conditions [Ce⁴⁺]/[PMG] = 1/5, [H⁺] = 1.0 × 10^?2 mole/l. In other words, the graft frequency was 12 per 100 monomer units of PMG. Such a high frequency of the grafts was, however, greatly decreased when the acid concentration was increased. Characteristics of the highly branched structure were revealed by the relationship between intrinsic viscosity and graft frequency, which showed a downward curvature with the increasing graft frequency. Influences of acid and ceric ion concentrations on the copolymerization were kinetically evaluated. The rate of polymerization was found to be first-order with respect to ceric ion and proportional to the square of the reciprocal acid concentration. The result suggests that the graft frequency is dependent upon the rate of polymerization.     

Co(en)3[B4O5(OH)4]Cl·3H2O和[Ni(en)3][B5O6(OH)4]2·2H2O的合成、结构以及热力学性质

利用水热法合成了两种过渡金属配合物为模板剂的含水硼酸盐晶体Co(en)3[B4O5(OH)4]Cl·3H2O(1) 和 [Ni(en)3][B5O6(OH)4]2·2H2O (2),并通过元素分析、X射线单晶衍射、红外光谱及热重分析对其进行了表征。化合物1晶体结构的主要特点是在所有组成Co(en)33+, [B4O5(OH)4]2–, Cl– 和 H2O之间通过O–H…O、O–H…Cl、N–H…Cl和N–H…O四种氢键连接形成网状超分子结构。化合物2晶体结构的特点是[B5O6(OH)4]–阴离子通过O–H…O氢键连接形成沿a方向有较大通道的三维超分子骨架,模板剂[Ni(en)3]2+阳离子和结晶水分子填充在通道中。     

Comparison of Electrochemical Synthesis of Ammonia by Using Sulfonated Polysulfone and Nafion Membrane with Sm1.5Sr0.5NiO4

Polysulfone (PSF) and sulfonated polysulfone (SPSF) were synthesized and characterized by IR spectrum. Sm_1.5Sr_0.5NiO₄ (SSN) and Ni‐Ce_0.8Sm_0.2O_2?δ (Ni‐SDC, Ni‐samarium doped ceria) were prepared and characterized by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). Ammonia was synthesized from wet hydrogen and dry nitrogen with applied voltage, using SSN as cathode, Ni‐SDC as anode, Nafion and SPSF as proton membrane respectively. The performances of Nafion and SPSF membranes in ammonia synthesis were investigated and compared at atmospheric pressure and low temperature (25–100°C). The results demonstrated that the proton conducting performances of Nafion and SPSF membranes were similar and the highest rates of evolution of ammonia were up to 1.05×10^?8 and 1.03×10^?8 mol·cm^?2·s^?1 respectively at 80°C and 2.5 V.