Graft polymerization of octafluoropentyl acrylate on polycaproamide thread

Octafluoropentyl acrylate [H(CF₂CF₂)₂CH₂‐ C(O)CH?CH₂] and polycaproamide (PA‐6) thread were copolymerized with a tert‐butyl hydroperoxide initiator. The fluorine content of the thread was 0.87–1.33% after copolymerization. The creation of ester polyfluorinated alkyl groups on the end of the polyamide macromolecules by the homolytical substitution of hydrogen atoms in the α‐CH₂? group of the ? HN? CH₂? (CH₂)₄? C(O)? chain led to an increase in the tensile strength of the PA‐6 thread. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4028–4029, 2006     

Polymerisation von Vinylchlorid bei Atmosphärendruck. 2. Chemische und spektroskopische Methoden zur Charakterisierung von U-PVC

PVC, which was polymerized at atmospheric pressure (so called U-PVC) contains relatively high concentrations of defects contrary to normal PVC. The number of chain scissions in U-PVC determined by ozonolytic cleavage resulted in values between 0.026 and 0.058 per 100 monomer units (100 VC). The determination of allylic and tertiary chlorine was done by selective reaction of U-PVC with phenol and NMR-spectroscopic investigations of the phenolized polymers. The average ‘labile chlorine’ content amounts to 0.65/100 VC. Hydroxyl radicals formed during the decomposition of the initiator (K₂S₂O₈) resulted in alcoholic endgroups in U-PVC, which were detectable in the IR-spectrum at 3580 cm^?1. The termination with hydroxyradicals also led to structures at the chain ends changing into ß-chloraldehyde groups accompanied by HCl-elimination. The corresponding signal in the IR-spectrum appeared at 1720 cm^?1. U-PVC raw material contained about two branch points per 100 VC. The CCl₄ extracts of the same polymers revealed the ten-fold content of branching. The olefinic structures ? CH?CH? CHCl? and ? CHCl? CH?CH₂ were determined by NMR-spectroscopy. The concentrations of each ranged from 0.25 to 0.3/100 VC. A typical double bond for U-PVC at the chain ends represented the structure ? CH?CH? CH₂Cl, which was preferably present in the low molecular weight material.     

The Photodissociation of Ground and Vibrationally Excited Halogenated Alkanes

The dynamics of photodissociation of small halogenated alkanes, in both their ground and vibrationally excited states, is investigated. The yield of H, Cl(²P_2/3), and Cl(²P_1/2) fragments was measured by (2 + 1) resonance-enhanced multiphoton ionization in a time-of-flight mass spectrometer. We report results from the 193 nm photolysis of ground state CHF₂Cl, CH₃CF₂Cl, CH₃CFCl₂, and OH₃Cl and the 237–243 nm photolysis of CH₃Cl excited to the fourth C–H stretch overtone level. The branching ratios depend on the molecular structure, the accessed excited potential surfaces and, as a consequence, on the dissociation dynamics.     

Structural characterization and thermal behaviour of block copolymers of polydimethylsiloxane and polyamide having trichlorogermyl pendant groups

Block copolymers having a pendant trichlorogermyl group as a part of polyamide segment? (CO? R′? CO? NH? Ar? NH? )_xCO? R′? CO? and polydimethylsiloxane of general formula [(? CO? R′? CO? HN? Ar? NH)_x? CO? R′? CO? NH(CH₂)₃SiO(CH₃)₂ ((CH₃)₂SiO)_ySi(CH₃)₂(CH₂)₃ NH? ]_n (where R′ = CH₂CH(GeCl₃), CH(CH₃)CH(GeCl₃), CH(GeCl₃)CH(CH₃); Ar = C₆H₄, (? C₆H₃? CH₃)₂, (? C₆H₃? OCH₃)₂, 2,5‐(CH₃)₂? C₆H₂, C₆H₄? O? C₆H₄) were prepared by a polycondensation reaction and characterized using CHN and Ge analysis, Fourier transform infrared (FTIR) and ¹H NMR spectroscopy, thermogravimetric analysis (TGA) and molecular weight determination. They have a lamellar structure with weight‐average molecular weight in the range 1.21 × 10⁵–4.79 × 10⁵ g mol^?1. These copolymers display two glass transition temperatures and have an average decomposition temperature of 489 °C. TGA, FTIR and gas chromatography/mass spectrometry studies indicate that degradation of these block copolymers results in carbon monoxide, oligomeric siloxanes and polyamide fragments. They are thermally stable due to the hydrogen bonded interlinked chains of polyamide, while they absorb water due to the presence of Ge? Cl bonding. Copyright © 2010 Society of Chemical Industry     

New fluorinated polysiloxanes containing an ester function in the spacer—II. Surface tension studies

The surface tensions of fluorinated polysiloxanes prepared by hydrosilylation of unsaturated perfluoroalkyl esters derived from undecylenic acid [CH₂?CH? (CH₂)₈? COO? CH₂? CH₂? R_F, with R_F = C₆F₁₃, C₈F₁₇, and C₈F₁₇? (CH₂)₁₀COO? CH₂? CH₂? CH?CH₂] by methylhydrodimethylsiloxane copolymers of various Si? H contents have been measured. The critical surface tensions, γ_c, and the solid surface tensions, γ^D_s, were deduced from n-alkane and water contact angle data. They decrease as the perfluoroalkyl graft content of the copolymers increases. Some of them, which are in the range of the lowest surface tension fluoro polymers known, are observed when the fluorinated segments are self-organized at the interface, i.e. when the polymers are mesomorphous or crystalline at room temperature.     

Facile,Efficient Copolymerization of Ethylene with Bicyclic,Non‐Conjugated Dienes by Titanium Complexes Bearing Bis(β‐Enaminoketonato) Ligands

Copolymerizations of ethylene with 5‐vinyl‐2‐norbornene or 5‐ethylidene‐2‐norbornene under the action of various titanium complexes bearing bis(β‐enaminoketonato) chelate ligands of the type, [R¹NC(R²)CHC(R³)O]₂TiCl₂ ( 1 , R¹=Ph, R²=CF₃, R³=Ph; 2 , R¹=C₆H₄F‐p, R²=CF₃, R³=Ph; 3 , R¹=Ph, R²=CF₃, R³=t‐Bu; 4 , R¹=C₆H₄F‐p, R²=CF₃, R³=t‐Bu; 5 , R¹=Ph, R²=CH₃, R³=CF₃; 6 , R¹=C₆H₄F‐p, R²=CH₃, R³=CF₃), have been shown to occur with the regioselective insertion of the endocyclic double bond of the monomer into the copolymer chain, leaving the exocyclic vinyl double bond as a pendant unsaturation. The ligand modification strongly affects the copolymerization behaviour. High catalytic activities and efficient co‐monomer incorporation can be easily obtained by optimizing the catalyst structures and polymerization conditions.     

IN SITU visualization of water adsorption in cellulose nanofiber film with micrometer spatial resolution using micro-FTIR imaging

Hygroscopic behavior is an inherent characteristic of nanocellulose film which strongly affects its applications. In order to gain a better understanding of water adsorption, micro-Fourier transform infrared (FTIR) imaging was used to investigate the water adsorption in cellulose nanofiber film with a spatial resolution of 20 um. Four spectral peaks at 2905?cm^?1, 1428?cm^?1, 1371?cm^?1, and 1317?cm^?1 attributed to CH and CH₂ groups were used to generate 2D micro-FTIR images of cellulose distribution, and the most intense peak at 3348?cm^?1 was employed to generate 2D micro-FTIR image of OH group distribution. On this basis, difference 2D micro-FTIR images of OH group distribution at different relative humidity (RH) levels demonstrated the development of adsorbed water distribution in cellulose nanofiber film during the water adsorption process. The study results confirmed that the micro-FTIR imaging was one promising tool for in situ visualization of water adsorption with micron-scale resolution.     

Plasma polymerization of tetrafluoroethylene

The plasma polymerization of C₂F₄ was carried out in both continuous wave and pulsed rf discharges to establish the effects of reaction conditions on the kinetics of polymer deposition and the polymer structure. ESCA spectra of the polymer show evidence for ? CF₃, ? CF₂, and ? CH₂? groups. Under conditions favoring low deposition rates, the dominant functional group is ? CF₂? . At higher deposition rates the concentration of ? CF₂? groups is reduced and a more crosslinked polymer is produced. Both polymer deposition rates and polymer structures were essentially identical when using continuous wave and pulsed rf discharges.     

New fluorine-containing polyorganosilsesquioxanes: Preparation and properties

It has been found that hydrolysis of three-functional alkoxysilanes, such as R^FOCH₂Si(OR^F)₃, R^F = CH₂CF₃, CH₂CF₂CF₃, CH₂CF₂CF₂CF₃, and CH₂CF₂CF₂CF₂CF₃, under mild conditions upon exposure to air moisture in the presence of ??-aminopropyltriethoxysilane results in the formation of hydrophobic coatings from fluorine-containing polyorganosilsesquioxanes directly on the substrate. Polymers have a layered ladder structure. The hydrophobicity and low values of refractive indices, surface energy, and its polar component, as well as the simplicity of the preparation, determine the possibility of using polyorganosilsesquioxane films as antireflection protective coatings for laser optics.     

Polyorganosiloxanes containing both ester and hydride functionalities: A detailed study by 1H and 13C NMR spectroscopy

A total of eighteen linear polysiloxanes of general formula Me₃SiO-(MeSi(E)O)_x(MeSi(H)O)_ySiMe₃ (E = —(CH₂)_nester; x+y = 40) have been prepared by the platinum catalysed addition of CH₂=CH(CH₂)_n-2 -ester to Me₃SiO-(MeSi(H)O)₄₀SiMe₃ under anhydrous conditions. Polymers containing the ester functionalities—(CH₂)₃CO₂R(R = Me, CF₃, Et, Pr, and CH₂COMe),—(CH₂)₃-CHMeCO₂Et, —(CH₂)₂CH(CO₂Me)₂, —(CH₂)₃CH(CO₂Et)₂, -(CH₂)₃CO₂CH= CHCO₂CH₂CH=CH₂ and —(CH₂)₃CO₂C₆H₄CO₂ CH₂CH=CH₂ have been characterised by analysis and ¹H and ¹³C NMR spectroscopies. Factors affecting Markownik off versus anti-Markownikoff addition of allyl acetate to this polymethylsiloxane have also been explored.     

Experimental Evaluation of the Adsorption,Diffusion, and Separation of CH4/N2 and CH4/CO2 Mixtures on Al-BDC MOF

Adsorption equilibrium, thermodynamics, and kinetics of CH₄, N₂, and CO₂ were investigated by volumetric-chromatographic and inverse gas chromatographic (IGC) methods on the Al-BDC MOF. The binary adsorption data from the volumetric-chromatographic experiments represents that the Al-BDC MOF has a high CO₂/CH₄ selectivity ca. 11 and a CH₄/N₂ selectivity ca. 4.3 at 303 K, and appears to be a good candidate for the CH₄ separation. The initial adsorption heats of CH₄, N₂, and CO₂ on the Al-BDC MOF were determined to be 15.3, 11.5, and 32.2 kJmol^?1 by IGC method, respectively. Moreover, the micropore diffusivities of N₂, CH₄ and CO₂ in the Al-BDC MOF at 303 K were also estimated to be 1.58 × 10^?7 cm²/s, 7.04 × 10^?8 cm²/s, and 3.95 × 10^?9 cm²/s, respectively. The results indicate that micropores play a crucial role in the adsorptive separation of the CH₄/N₂ and CH₄/CO₂ mixtures, and the IGC method is a validity manner to estimate the thermodynamic and kinetic parameters of MOF adsorbents.     

Study on syntheses and properties of 2,2′‐mercaptoethylsulfide dimethacrylate transparent homo‐ and copolymer resins having high refractive index

2,2′‐Mercaptoethylsulfide dimethacrylate (MESDMA) was synthesized from 2,2′‐mercaptoethylsulfide (MES) by a Phase‐Transfer Catalysis technique and, was characterized and corroborated by ¹H‐NMR and FTIR spectra. Except for the poor impact strength, the MESDMA homopolymer resin shows better comprehensive properties, such as a higher refractive index (1.625), lower dispersion (Abbe's number 36), and good heat‐resistance (T_g 150°C) and surface hardness (3H), etc. Copolymerizing with styrene (St) can modify most of the properties of the resin. The refractive index, Abbe's number, onset wavelength, density, water‐absorption ratio, and absorption intensity of peaks in NIR region, etc. all display a regular change along with the proportion of MESDMA/St. The main absorption peaks in NIR region are assigned as follows: 1680 (first overtone) and 1144 nm (second overtone) to the phenyl C—H vibration of polystyrene; 1694 nm (first overtone) to ν(CH₃); 1730 and 1750 nm (first overtone) to ν(CH₂) for ordinary CH₂ and for CH₂ connected with S or COS groups, respectively; and 1186 nm (second overtone) to aliphatic C—H vibration. The prominent advantage achieved by copolymerization is that the impact strength can be improved as much as 10‐fold at a proper composition of the monomers (75% St). © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1474–1479, 2000     

Electrolysis of mixed melt of (CH3)4NF·mHF+x wt.% CsF·2.0HF with nickel anode

A new process for electrolytic synthesis of a perfluorinated compound using mixed melts of (CH₃)₄NF·4.0HF+x wt.% CsF·2.0HF as electrolytes and Ni sheet anode at room temperature was developed. The addition of CsF·2.0HF reduced the overvoltage of the Ni anode. The surface film on the anode formed in the presence of CsF·2.0HF consisted of inorganic compounds of NiF₂, CsNi₂F₆, and an organic compound of (CH₃)₄NF. The presence of CsNi₂F₆, which is a highly oxidized nickel compound, gave a high electronic conductivity to the film and decreased the anode overvoltage. The gas evolved on the anode was composed of (CF₃)₃N and CF₄ as main products with small amounts of NF₃, C₂F₆, CHF₃, C₂HF₅, CF₃N(CF₂H)₂, and (CF₃)₂NCHF₂. The addition of 20 wt.% CsF·2.0HF gave the highest ratio of (CF₃)₃N of 40.5% when the electrolysis was carried out at 5 mA cm⁻² at room temperature.     

Phosphorus-Containing polyurethanes based on bisphenol-AF,prepared by N-alkylation

Phosphorus-containing polyurethanes (PU-P) based on bisphenol-AF were synthesized by N-alkylation in a two-step process. First, the polymer was metalated with sodium hydride; then the prepared urethane polyanion was treated with diethyl 2-bromoethyl phosphate. IR spectra exhibited characteristic absorptions at 1303 cm⁻¹ (PO stretch), 1015 cm⁻¹ (CH stretch), 1646 cm⁻¹ (CO stretch), 1231 cm⁻¹ (CNH), and 1053 cm⁻¹ (CO O C stretch). In the ¹H-NMR spectrum of the maximum substituted PU-P, the signal of the urethane proton (NH  CO O) at 9.87 ppm virtually disappeared as expected; new signals appeared at 1.20–1.24 ppm (POCH₂CH ₃) and 3.79 ppm (POCH ₂CH₃). Physical and thermal properties of the N-alkylated polymer were also investigated with differential scanning calorimetry (DSC), solubility, X-ray diffraction, thermogravimetric analysis (TGA), limiting oxygen index (LOI), and reduced viscosity. DSC analysis showed that T_g values were decreased from 81 to 43°C. The reduced viscosities of the PU-Ps were observed in the range of 0.23–0.18 dL g⁻¹. The results of TGA revealed that the thermal stability was decreased, because the phosphorus moiety in the PUs is readily dissociated thermally. The PU-Ps exhibited enhanced fire resistance because phosphorus simultaneously promoted carbonization of the polymer and inhibited combustion. The X-ray diffraction patterns of the PU-Ps showed that with increasing phosphorus content, the degree of crystallinity of the PUs decreased. N-alkylated PUs are soluble, not only in polar solvents such as N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, and H₂SO₄, but also in less polar solvents such as phenol, toluene, THF, and trichloroethylene. © 1996 John Wiley & Sons, Inc.     

Synthesis and Surface Activities of Novel Succinic Acid Monofluoroalkyl Sulfonate Surfactants

Two environmentally friendly succinic acid monofluoroalkyl sulfonate surfactants were synthesized from maleic anhydride and polyethylene glycol mono (1H,1H,7H‐dodecafluoroheptyl) ether, i.e. H(CF₂)₆CH₂OCH₂CH₂OCOCH(SO₃Na)CH₂COOH (FEOS‐1) and H(CF₂)₆CH₂(OCH₂CH₂)₃OCOCH(SO₃Na)CH₂COOH (FEOS‐3). The obtained surfactants were characterized by FT‐IR, ¹H NMR, ¹³C NMR and ¹⁹F NMR in detail. The synthesized fluorinated surfactants have a high thermal stability on the basis of thermogravimetric analysis. Their surface properties were examined and the results show that FEOS‐1 and FEOS‐3 surfactants can reduce the surface tension of water to 25.55 mN m^?1 at 10.25 mmol L^?1 and 21.63 mN m^?1 at 8.33 mmol L^?1, respectively; meanwhile, the introduction of oxyethylene groups enhances the hydrophilicity and micellar forming ability and the longer oxyethylene chains the better surface properties. The Krafft points (K_p) of FEOS‐1 and FEOS‐3 were both below 0 °C, which was lower than perfluoro‐n‐heptanesulfonic acid sodium salt (n‐C₇F₁₅SO₃Na, K_p = 56.5 °C) at a similar length of fluorocarbon chains. Comparison studies on two surfactants above and the conventional fluorocarbon surfactants, perfluorooctanoate of ammonium (PFOA) show that the surfactants have comparable properties to PFOA, thus offering an environmentally friendly synthesizing alternatives to PFOA.     

Effect of CsF-concentration on electrolytic conductivity, viscosity and anodic reaction of nickel electrode in (CH3)3N-CsF–HF system at room temperature

In order to increase the formation ratio of perfluorotrimethylamine, (CF₃)₃N, to overall anode gas in electrolytic production using Ni anode, mixed melts of (CH₃)₃N·mHF + CsF·2.3HF were used as electrolytes at room temperature. The ionic conductivity of the mixed melts decreased with an increase in the CsF concentration, whereas the viscosity of the mixed melts increased with increasing the CsF concentration. AC impedance and XRD analysis revealed that the presence of CsNi₂F₆ in the oxidized layer formed on the Ni anode after electrolysis. The gas evolved at the Ni anode was composed of (CF₃)₃N, (CF₃)₂CHF₂N, CF₃(CHF₂)₂N, (CHF₂)₃N, CF₄, NF₃, CHF₃, C₂HF₅, and C₂F₆. The best ratio of (CF₃)₃N to the overall anode gas (52.11%) was obtained in the electrolyte of (CH₃)₃N·5.0HF + 50 wt% CsF·2.3HF mixed melt at 20 mA cm⁻².     

Intermolecular Interactions Between Methanol/Water Molecules and Nafion™ Membrane: An Infrared Spectroscopy Study

The intermolecular interactions between methanol/water and Nafion™ membranes have been investigated using IR spectroscopy. The evolution of IR spectra of the Nafion™ membranes, immersed in various concentrations of methanol solution depends strongly on the methanol concentration. The O–H bending vibration modes at 1,636, 1,660 and 1,672 cm^–1 associated with the hydrogen bonding of (H₃O⁺…SO₃^–) as well as (CH₃OH₂⁺…SO₃^–), and at 1,702, 1,717 and 1,711–1,736 cm^–1 associated with the hydrogen bonding of (CF₂…H–O–CH₃), (CF₂…H–OH), (CF₂…⁺H₃O) and (CF₂…H–OSO₂^–) were observed. The vibration mode of (CF₂…H–O) was found to be appearing obviously at 3,821–3,900 cm^–1 when the Nafion™ membrane was immersed in the methanol solution with concentration higher than 6 M. On the other hand, the wavenumber of the O–H stretching peak increases with an increase in the methanol concentration. Results of IR spectra revealed that the methanol molecules show better capability to penetrate into the hydrophobic domain of the Nafion™ membrane than water. The intermolecular interaction between the hydrophobic domains of Nafion™ and methanol molecules becomes more observable at a higher methanol concentration.     

Tunning the Physical Properties of PVDF/PVC/Zinc Ferrite Nanocomposites Films for More Efficient Adsorption of Cd (II)

This work deals with the synthesis of ZnFe₂O₄ NPs and studies the effect of addition on the physical properties PVDF/PVC blend. XRD affirmed the formation of ZnFe₂O₄ NPs and HRTEM shows that the size of the prepared ZnFe₂O₄ NPs ranged from 20 to 55 nm. The effect of ZnFe₂O₄ on the behavior of PVDF/PVC was studied through XRD, ATR-FTIR, FESEM and UV–Visible spectroscopy. XRD revealed that the addition of ZnFe₂O₄ NPs enhanced the crystallinity of PVDF/PVC blend system and also confirmed the incorporation of ZnFe₂O₄ NPs by appearing a diffraction peak at 2θ equals 35°. ATR-FTIR affirmed the interaction between blend sample and ZnFe₂O₄ NPs by appearing new bands 554 cm^?1 and 421 cm^?1 which are corresponded to ZnFe₂O₄ NPs functional group with appearing a new band at 603 cm^?1. FESEM showed that the addition of ZnFe₂O₄ to PVDF/PVC blend improved surface properties, for example, roughness average has been increased from 319 to 414 nm while maximum height increased from 260 to 473 nm for PVDF/PVC and PVDF/PVC/10% ZnFe₂O₄, respectively. Optical properties and band gap calculations revealed that addition of ZnFe₂O₄ NPs changes the structure of polyblend samples which results due to the formation of localized states. The removal efficiency of Cd (II) by using PVDF/PVC/10% ZnFe₂O₄ reached about 50% at pH 6 after 60 min. the absorption mechanism as well as kinetics isotherm have been studied. It is found that adsorption of Cd (II) occurred through the Langmuir mechanism and fellow pseudo-second order isotherm.

     

Synthesis of polyphosphazene random copolymers bearing alkoxyethoxy and trifluoroethoxy functional groups

The anionically initiated copolymerization of (CH₃OCH₂CH₂O)(CF₃CH₂O)₂ P=N-Si(CH₃)₃, (CH₃OCH₂CH₂OCH₂CH₂O)(CF₃CH₂O)₂ P=N-Si(CH₃)₃, (CH₃OCH₂CH₂O)₂ (CF₃CH₂O) P=N-Si(CH₃)₃, and (CH₃OCH₂CH₂OCH₂CH₂O)₂ (CF₃CH₂O) P=N-Si(CH₃)₃ with (CF₃CH₂O)₃ P=N-Si(CH₃)₃ is reported. These materials were characterized by³¹P and¹H NMR, SEC, and DSC.In situ ³¹P NMR studies indicate that monomers are simultaneously consumed, SEC traces show that these random copolymers exhibit monomodal distributions, and there is a gradient in solubilities as well as thermal and mechanical properties which is dependent upon the repeating unit ratios.     

Synthesis, Characterization and Properties of New Lauryl Amidopropyl Trimethyl Ammoniums

A new lauryl amidopropyl trimethyl ammonium methyl carbonate with the formula CH₃(CH₂)₁₀CONH(CH₂)₃N⁺(CH₃)₃CH₃CO₃ ^? was synthesized via a high pressure process with tertiary amines and dimethyl carbonate, and its chemical structure was confirmed using ¹H-NMR spectra, mass spectral fragmentation, and FTIR spectroscopic analysis. In addition, several quaternary ammonium salts with new counterions X^? (X^?=HCO₃ ^?, HCOO^?, CH₃COO^?, CH₃CH(OH)COO^?) were also synthesized by the ion exchange reaction of methyl carbonate quaternary ammoniums with corresponding acids. The surface activities of these compounds were measured, including surface tension (??), critical micelle concentration and minimum surface area (A _min) at 25?°C. Adsorption and micellization free energies of these quaternary ammonium salts in their solutions showed a good tendency towards adsorption at interfaces. The antimicrobial activities are reported for the first time against representative bacteria and fungi for lauryl amidopropyl trimethyl ammoniums. It was found that the antimicrobial potency was Gram-positive bacteria?>?fungi?>?Gram-negative bacteria.