Design and Properties of New Functional Water – Soluble Polymers of Citraconic Anhydride (CA) and Related Copolymers

Summary The binary and ternary copolymers are synthesized by free-radical initiated binary copolymerization of citraconic anhydride (CA) with acrylamide (AAm) and terpolymerization of acrylamide (AAm) – citraconic anhydride (CA) – vinyl acetate (VA) monomer system. Co- and terpolymerization were carried out in the presence of benzoyl peroxide (BPO) as an initiator at 70 °C in benzene under nitrogen atmosphere. Structure and monomer unit composition of the copolymers, obtained from a wide range of monomer feed were determined by elemental analysis. Structural peculiarities of synthesized PAAm, [poly (AAm-alt-CA)] and [poly(AAm-co-CA-co-VA)] were characterized by using Fourier Transform Infrared (FTIR), Uv–vis, ¹H-NMR, X-ray diffraction (XRD), elemental analysis, analytical methods (titration methods) and viscometric measurements.     

Copolymerization without initiator of 1-(2-hydroxyethyl)aziridine and acrylamide

Summary 1-(2-Hydroxyethyl)aziridine as nucleophilic monomer was copolymerized in the absence of an initiator under various experimental conditions with acrylamide as electrophilic monomer. All copolymers were characterized by elemental analysis, IR, and ¹H-NMR spectroscopy. The viscosity measurements showed that the copolymers behave as polyelectrolytes. The copolymer composition was determined from elemental analysis and ¹H-NMR spectra.     

Spontaneous copolymerization of 1-(2-hydroxyethyl)aziridine with N-phenylmaleimide and p-methoxyphenylmaleimide

Summary The copolymerization of 1-(2-hydroxyethyl)aziridine as nucleophilic monomer with N-phenylmaleimide and p-methoxyphenylmaleimide as electrophilic monomer in the absence of an initiator in solution was investigated. Copolymerizations under different experimental conditions were carried out. The copolymers were characterized by FT-IR and ¹H-NMR spectroscopy. The copolymer compositions were determined by elemental analysis and ¹H-NMR spectroscopy. Almost all products are statistical copolymers.     

Water-soluble Copolymers of N-vinylpyrrolidone and Vinyl Acetate: Synthesis, Characterization, and Monomer Reactivity at High Conversions

Homogeneous copolymers of N-vinylpyrrolidone (VP) and vinyl acetate (VA) which form clear aqueous solutions were prepared by free radical polymerization in a solution of isopropanol alcohol, using 2,2-azobisisobutyronitrile as an initiator. They were characterized by FTIR, ¹H-NMR, and element analysis studies. The reactivity ratios of the monomer were computed by the Extended Kelen–Tüdós method at high conversions, using data from both ¹H-NMR and elemental analysis studies. The reactivity ratios of VP and VA in a homogenous copolymer were observed to be very different from that of a heterogeneous copolymer. Additional information was obtained by finding out the sequence length distribution for copolymers.     

Kinetics of the Anionic Ring Opening Polymerization of Cyclosiloxanes Initiated with a Superbase

Kinetics of the anionic ring opening polymerization of octamethylcyclotetrasiloxane, D₄, and hexamethylcyclotrisiloxane, D₃, in toluene solution initiated by hexapyrrolidinediphosphazenium hydroxide, P₂Pyr₆ ⁺OH^– were studied. Reactions are first order both in monomer and in initiator. The specific rate of the D₃ polymerization is higher than that of D₄ by about 2–3 orders of magnitudes. Activation energies are 18.1 kcal mol^–1 for D₄ and 11 kcal mol^–1 for D₃. The back-biting reaction leading to decamethylcyclopentasiloxane, D₅, was followed in the polymerization of D₄. This reaction is retarded by the presence of monomer. The kinetics is interpreted in terms of a mechanism in which the active propagation center appears mostly as a monomer separated ion pair, which is also the intermediate in the propagation step.     

Measurements on the temperature dependence of the cationic polymerization of styrene in CH2Cl2 with CF3SO3H as catalyst

Summary The cationic polymerization of styrene in CH₂Cl₂ with CF₃SO₃H as catalyst and at low monomer concentrations shows, at –15°C, –45°C and –60°C, the same formal dependence on monomer concentration. The dependence on the catalyst concentration is approximately but not exactly of a third order.The unimodal molecular weight distributions at [M]_o<0.2 mol·1^–1 become broader with decreasing polymerization temperature and increasing monomer concentration and change to bimodal or trimodal distributions at [m]_o>0.2 mol·1^–1. The addition of (Bu)₄N⁺CF₃SO₃ ^– to the polymerization system shows that the two higher molecular peaks are produced by free ions. The activation energy of the total reaction is found to be 3.5 kcal·mol^–1.I thank Prof. G. V. Schulz for interesting discussions and the possibility to work in his group, G. Greschner for a computer program and the Alexander von Humboldt Stiftung for their financial help.     

Characterization of electroless Ni-Mo-P/SnO2/Ti electrodes for oxygen evolution in alkaline solution

Ni-Mo-P alloy electrodes, prepared by electroless plating, were characterized for application to oxygen evolution. The rate constants were estimated for oxygen evolution on electrodes prepared at various Mo-complex concentrations. The surface area and the crystallinity increase with increasing Mo content. The electrochemical characteristics of the electrodes were identified in relation to morphology and the structure of the surface. The results show that the electroless Ni-Mo-P electrode prepared at a Mo-complex concentration of 0.011 m provided the best electrocatalytic activity for oxygen evolution.List of symbols b Tafel slope (mV dec^–1) - b F/RT (mV^–1) - F Faraday constant (96 500 C mol^–1) - j current density (mA cm^–2) - k₁ reaction rate of Reaction 1, (mol^–1 cm³ s^–) - k ₁ = k₁C _OH ^–(mol cm^–2 s^–1) - k ₁₀ rate constant of Reaction 1 at = 0 (mol cm^–2 s^–1) - k_c1 rate constant of Reaction 2 (mol^–1 cm³ s^–1) - k _c1 = k_c1C _{H 2O} (mol cm^–2 s^–1) - k_c2 rate constant of chemical Reaction 3 (mol^–1 cm² s^–1) - k _c2 = k_c2² (mol cm^–2 s^–1) - k_c3 rate constant of Reaction 4 (mol^–1 cm² s^–1) - Q _a anodic capacity (mC) - Q _c cathodic capacity (mC) - R gas constant (8.314 J mol^–1 K^–1) - R _ct charge transfer resistance ( cm²) - R _ads charge transfer resistance due to adsorption effect ( cm²) - C _d1 double layer capacity (mF cm^–2) - _{C ads} double layer capacity due to adsorption effect (mF cm^–2) - T temperature (K) Greek symbols anodic transfer coefficient - _{O 2} oxygen overpotential (mV) - saturation concentration of surface oxide on nickel (mol cm^–2)     

Preparation of methoxy poly(ethyleneglycol)-block-poly(caprolactone) via activated monomer mechanism and examination of micellar characterization

Summary The polymerization of ε–caprolactone (CL) in the presence of HCl·Et₂O via activated monomer mechanism was performed to synthesize diblock copolymers composed of methoxy polyethyleneglycol (MPEG) and poly(ε–caprolactone) (PCL). The obtained PCLs had molecular weights close to the theoretical values calculated from the CL to MPEG molar ratios and exibited monomodal GPC curves. We successfully prepared MPEG and PCL diblock copolymers by activated monomer mechanism. The micellar characterization of MPEG-PCL diblock copolymers in an aqueous phase was carried out by using NMR, dynamic light scattering, AFM and fluorescence techniques. The diblock copolymers formed micelles with a critical micelle concentration (CMC) ranging 2.07×10^-2–1.16×10^-3 mg/mL depended on the block lengths of diblock copolymers. The diameters of micelles, measured by dynamic light scattering, were 100–250 nm. Most micelles exhibited a spherical shape in AFM.     

“Spontaneous Copolymerization of p-Chlorophenylmaleimide with 2-Methylaziridine”

Abstract

p-Chlorophenylmaleimide as an electrophilic monomer was copolymerized in the absence of initiator with 2-methylaziridine as nuclephilic monomer. The copolymers were characterized by elemental analysis, FT-IR, and ¹H-NMR spectroscopy. The copolymer compositions were determined by chloro elemental analysis and ¹H-NMR spectroscopy. 2-Methylaziridine is more reactive than p-chlorophenylmaleimide yielding statistical copolymers. Mn, determined by vapor pressure osmometry, varied between 3.000 and 6.700 g/mol.     

Unsaturated Copolyesters from Macrolactone/Norbornene: Toward Reaction Kinetics of Metathesis Copolymerization Using Ruthenium Carbene Catalysts

Unsaturated copolyesters are of great interest in polymer science due to their broad potential applications and sustainability. Copolyesters were synthesized from the ring-opening metathesis copolymerization of ω-6-hexadecenlactone (HDL) and norbornene (NB) using ruthenium-alkylidene [Ru(Cl₂)(=CHPh)(1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)(PCy₃)] (Ru1), [Ru(Cl)₂(=CHPh)(PCy₃)₂] (Ru2), and ruthenium-vinylidene [RuCl₂(=C=CH(p-C₆H₄CF₃))(PCy₃)₂] (Ru3) catalysts, respectively, yielding HDL-NB copolymers with different ratios of the monomer HDL in the feed. The activity of N-heterocyclic-carbene (NHC) (Ru1) and phosphine (Ru2 and Ru3) ligands containing ruthenium-carbene catalysts were evaluated in the synthesis of copolymer HDL-NB. The catalysts Ru1 with an NHC ligand showed superior activity and stability over catalysts Ru2 and Ru3 bearing PCy₃ ligands. The incorporation of the monomers in the copolymers determined by ¹H-NMR spectroscopy was similar to that of the HDL-NB values in the feed. Experiments, at distinct monomer molar ratios, were carried out using the catalysts Ru1–Ru3 to determine the copolymerization reactivity constants by applying the Mayo–Lewis and Fineman–Ross methods. The copolymer distribution under equilibrium conditions was studied by the ¹³C NMR spectra, indicating that the copolymer HDL-NB is a gradient copolymer. The main factor determining the decrease in melting temperature is the inclusion of norbornene units, indicating that the PNB units permeate trough the HDL chains. The copolymers with different molar ratios [HDL]/[NB] have good thermal stability up to 411 °C in comparison with the homopolymer PHDL (384 °C). Further, the stress–strain measurements in tension for these copolymers depicted the appreciable increment in stress values as the NB content increases.     

The first P–N containing RuCl3NO complex: fac-[RuCl3(NO)(P–N)] (P–N = [o-(N,N-dimethylamino)phenyl]diphenylphosphine)

Complex fac-[RuCl₃(NO)(P–N)] was synthesized from [RuCl₃(H₂O)₂(NO)] in methanol solution under reflux. The orange solid obtained was characterized by NMR (³¹P{¹H}, ¹H, ¹³C) and, cyclic voltammetry, ESI-MS, IR, elemental analysis and X-ray diffraction structure determination. The ³¹P{¹H} reveals the presence of singlet at 36 ppm. IR N–O stretching as KBr pellets or CH₂Cl₂ solution presented 1866 cm⁻¹ and 1872 cm⁻¹, respectively.     

Intrinsic kinetics of Fischer–Tropsch reactions over an industrial Co–Ru/γ-Al2O3 catalyst in slurry phase reactor

The rate of Fischer–Tropsch synthesis over an industrial well-characterized Co–Ru/γ-Al₂O₃ catalyst was studied in a laboratory well mixed, continuous flow, slurry reactor under the conditions relevant to industrial operations as follows: temperature of 200–240 °C, pressure of 20–35 bar, H₂/CO feed ratio of 1.0–2.5, gas hourly space velocity of 500–1500 N cm³ g_cat^− 1 h^− 1 and conversions of 10–84% of carbon monoxide and 13–89% of hydrogen. The ranges of partial pressures of CO and H₂ have been chosen as 5–15 and 10–25 bar respectively. Five kinetic models are considered: one empirical power law model and four variations of the Langmuir–Hinshelwood–Hougen–Watson representation. All models considered incorporate a strong inhibition due to CO adsorption. The data of this study are fitted fairly well by a simple LHHW form − R_H2 + CO = ap_H2^0.988p_CO^0.508 / (1 + bp_CO^0.508)² in comparison to fits of the same data by several other representative LHHW rate forms proposed in other works. The apparent activation energy was 94–103 kJ/mol. Kinetic parameters are determined using the genetic algorithm approach (GA), followed by the Levenberg–Marquardt (LM) method to make refined optimization, and are validated by means of statistical analysis. Also, the performance of the catalyst for Fischer–Tropsch synthesis and the hydrocarbon product distributions were investigated under different reaction conditions.     

UV-Light Absorption Properties of Cr-Doped Polyethyleneglycol (PEG)/γ-Glycidoxypropyltrimethoxysilane (GPTMS)/Chelated-Titanium Coating Materials Prepared by the Sol–Gel Process

New hybrid inorganic–organic glass coating materials, which contain polyethyleneglycol/γ-glycidoxypropyltrimethoxysilane/titanium(IV)-n-propoxide(2-methoxyethylacetoacetate)/chromium(III)nitrate [PEG/GPTMS/Ti(OR)(2-MEAA)/Cr³⁺] have been developed for UV-light absorption by using the sol–gel process. The effect of agitation time and temperature on UV-light absorption was investigated. The titanium complex was characterized by ¹H-NMR and FTIR spectroscopies. UV–Vis spectroscopy was used to investigate the optical properties of the coating materials. The results show that the coated glass has very low transmission in the UV region (300–400 nm) compared to the uncoated glass, especially at 150, 200, 250 and 300°C treatment temperatures after 1- and 18-hour agitation times. The UV-light transmission of the coated glass was not different from the uncoated glass between 80–100°C and 350–500°C.     

A novel benzoxazine monomer with methacrylate functionality and its thermally curable (co)polymers

Benzoxazine monomer with methacrylate functionality, namely 2-(2-(2H-benzo[e][1,3]oxazin-3(4H)-yl)ethoxy) ethyl methacrylate (BEM) was synthesized by simple esterification reaction of hydroxyl containing benzoxazine (B–OH) with methacryloyl chloride, and characterized. BEM was then copolymerized with styrene in 1:4 mol ratio by free radical polymerization using 2,2′-azobis(isobutyronitrile) (AIBN) as initiator. The structure, chemical composition, and molecular weight characteristics of the resulting copolymer were confirmed by FT-IR, ¹H-NMR spectroscopy, and GPC, respectively. The curing behavior and thermal properties of both monomer and copolymer were also studied by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA).     

The polymerization of acenaphthylene by sulphuric acid in methylenedichloride

Summary Acenaphthylene was polymerized in methylenedichloride at 273, 291 and 308 K by sulphuric acid. The initiation step takes place by addition of the proton of sulphuric acid to the monomer. The propagation step is through ion-pairs, and the propagation constants are first-order with respect to the monomer and initiator(k_p = 0.22 M^–1. s^–1(273K), k_p=0.88 M^–1. s^–1(291K), k_p = 2.81 M^–1. s^–1 (308K)). There is not appreciable loss of active centres, being this confirmed by experiments carried out with succesive additions of monomer. The molecular weights obtained confirm the importance of processes to monomer in this polymerization.     

Spontaneous copolymerization of N-(2-hydroxyethyl)ethyleneimine with maleic anhydride

Summary The copolymerization of N-(2-hydroxyethyl)ethyleneimine, (HEEI) as nucleophilic monomer and maleic anhydride (MA) as electrophilic monomer in the absence of initiator in acetonitrile was investigated. Copolymers were characterized by IR, ¹H-NMR and ¹³C-NMR spectroscopy. The copolymer composition depends on the monomer ratio in the feed, determined by ¹H-NMR spectroscopy. The presence of MA bridges between copolymer chains was established by spectroscopic analysis. At lower temperature the yield and molecular weight of copolymers decrease as well as the MA unit content in the copolymer.     

Complexation of Titanium Alkoxides with Cis-2-butene-1,4-diol and Hydrolysis of Their Products

Reaction of Ti(OEt)₄ and Ti(OBu ⁿ )₄ with cis-2-butene-1,4-diol (B.diol-2H) in 1:1 molar ratio was studied at room temperature using the sol-gel process. ¹³C{¹H}- and ¹H-NMR data showed that all the B.diol-2H completely reacted with both titanium alkoxides. Each of the products was hydrolyzed by water. The new hydrolyzed products were characterized by ¹³C- and ¹H-NMR spectroscopy and Karl–Fischer Titration. Thermogravimetric and differential thermal analyses (TGA-DTA) of the hydrolyzed-products were also studied.     

In situ FTIR and UV/VIS spectroscopic study of the generation of anionic Pt-carbonyl complexes within a faujasite matrix

The temporal generation of anionic platinum-carbonyl complexes in platinum ionexchanged zeolites X and Y by reductive carbonylation at 10⁵ Pa and 363 K is monitored by in situ UV/VIS and FTIR spectroscopy. A monomer [Pt₃(CO)₆]^2–, exhibiting bands at 318 and 456 nm in the UV/VIS spectra and at 1790 and 2025 cm^–1 in the FTIR spectra, is the only platinum/species formed in NaX. The monomer as well as oligomers are generated in NaY, where the formation of the latter species is due to the stronger acidity in the NaY as compared to NaX. The decomposition of the complexes results in the generation of Pt clusters of the size 1 nm.     

Novel Supramolecular Square Grid-Like Structure: Synthesis and Characterization of [(Me3Sn)2CrO4]

Reactions of K₂Cr₂O₇ and K₂CrO₄ with Me₃SnCl yielded [(Me₃Sn)₂CrO₄] (1) and [(Me₃Sn)₂CrO₄(Me₃SnOH)] (2), respectively, which were characterized by elemental analysis, ¹H-NMR spectroscopy, and an X-ray diffraction study. Compound 1 shows a novel square grid-like structure consisting of CrO₄ ^2– and Me₃Sn⁺ ions, whereas 2 exhibits a three-dimensional structure composed of CrO₄ ^2–, Me₃Sn⁺, and [(Me₃Sn)₂SnOH]⁺ ions.     

Synthesis, Characterization and Antimicrobial Properties of Oligomer and Monomer/Oligomer–Metal Complexes of 2-[(Pyridine-3-yl-methylene)amino]phenol

Oligo-2-[(pyridine-3-yl-methylene)amino]phenol (2-PMAP) is synthesized by the oxidative polycondensation (OP) in aqueous alkaline medium using air as oxidant. At optimum reaction conditions, the yield of products is 71%. The structures of the monomer and oligomer were confirmed by FT-IR, UV–Vis, ¹H-NMR, ¹³C-NMR and elemental analysis. Characterization was made by thermogravimetric analysis-differential thermal analysis (TGA-DTA), size exclusion chromatography (SEC) and solubility. The ¹H-NMR and ¹³C-NMR data show that polymerization proceeds by C–C and C–O coupling of the ortho and para positions (–OH group and oxyphenylene group) of 2-[(pyridine-3-yl-methylene)amino]phenol. The molecular weight distribution of the product was determined by SEC. The number-average molecular weight (M _n ), weight-average molecular weight (M _w ) and polydispersity index (PDI) of O-2-PMAP are 7150, 8000 g mol⁻¹ and 1.119 for air oxidant, respectively. Thermal analysis results of O-2-PMAP indicate stability against thermal decomposition. Thermal analyses of 2-PMAP, 2-PMAP-Cd, 2-PMAP-Co, 2-PMAP-Cu, 2-PMAP-Zn, O-2-PMAP, O-2-PMAP-Cd, O-2-PMAP-Co, O-2-PMAP-Cu and O-2-PMAP-Zn monomer/oligomer–metal complexes were investigated under a N₂ atmosphere between 15 and 1000 °C. Antibacterial and antifungal activity of the synthesized compounds was examined against selected bacteria and fungi.