Microwave spectrum of propionyl chloride

The microwave spectrum of propionyl chloride has been investigated in the region 18.0–40.0 GHz, and transitions due to a cis conformer have been assigned. This form has a heavy atom planar configuration and the methyl group and the carbonyl oxygen atom are cis to each other. Using the substitution structures of propionic acid and acetyl chloride as molecular models for the propionyl chloride molecule, good agreement is found between observed and calculateò effective rotational constants. For the ³⁵Cl species satellite spectra assigned to the first four excited states of the C-C torsional mode have been observed together with the first excited state of the methyl torsional mode. The ground state spectrum has also been assigned for the ³⁷Cl species. Relative intensity measurements yielded the lowest C-C torsional vibration frequency of 86 ± 10 cm^?1. The CH₃ internal rotation frequency was found to be 197 cm^?1. Nuclear quadrupole coupling constants were determined for the ground state of the ³⁵Cl and ³⁷Cl species. From observed A-E splittings of ^bQ-branch transitions of the first excited state of the methyl torsional mode a barrier to internal rotation was estimated to be V₃ = 2480 ± 40 cal mol^?1 (867 ± 14 cm^?1).     

Surface-enhanced raman scattering from poly(4-vinyl pyridine)

Surface-enhanced Raman scattering (SERS) has been observed for poly(4-vinyl pyridine) absorbed onto silver island films. Bands near 1219 and 1613 cm^?1, which are weak in normal Raman spectra of PVP, are strong in SERS spectra, and the band near 1020 cm^?1, which is the strongest band in the normal spectra, is relatively weak in SERS. The strongest bands in the SERS spectra all belong to the same symmetry species as α_ZZ, implying that the pyridine moieties are adsorbed through the nitrogen atoms with a vertical conformation. The ring breathing mode of the pyridine rings is observed near 1020 cm^?1, a frequency characteristic of pyridinium ions or coordinated pyridine, providing further evidence for adsorption through the nitrogen atoms. Silver catalyzed photooxidation, which can lead to the appearance of artifacts in SERS spectra, particularly of polymers, can be reduced by overcoating SERS samples with thin films of polymers such as poly(methyl methacrylate) that have low Raman scattering cross sections.     

Raman spectra of styrene-sodium methacrylate copolymers—evidence for ion clustering

Raman spectra of a series of styrene-sodium methacrylate copolymers of varying sodium methacrylate contents have been investigated in the 425–100 cm^?1 region. The bands appearing at 254 and 166 cm^?1 have been attributed to ion multiplets and clusters, respectively. From an analysis of the intensities of these bands and a comparison of these intensities with those obtained from an analysis of dielectric data, it seems that Raman spectroscopy is a useful method for determining the concentrations of ions in the two different kinds of sites.     

Investigation of viscoelastic and thermal properties of cyclic carbonate bearing copolymers

In this paper, one-pot reaction of radical copolymerization of glycidyl methacrylate with methyl methacrylate, n-butyl acrylate and styrene under carbon dioxide atmosphere (1 atm) was employed to synthesize cyclic carbonate bearing copolymers. Obtained copolymers were characterized using ¹H NMR and FTIR spectroscopy. The viscoelastic and thermal properties of the resulted copolymers were investigated using dynamic mechanical thermal analysis and thermogravimetric analysis. Copolymer composition and monomer type had a significant effect on the properties of the copolymers. An increase in cyclic carbonate (2-oxo-1,3-dioxolane-4-yl-methyl methacrylate) content in the copolymer composition led to an increase in glass transition temperature, storage modulus and loss tangent as well as the thermal stability of the copolymers.     

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     

Preparation and photolysis of poly-4′-acetylacrylophenone and its copolymers with styrene and methyl methacrylate

Poly-4′-acetylacrylophenone (P4AcAP) and its copolymers with styrene (4AcAP/S) and methyl methacrylate (4AcAP/MMA) were prepared. Ultraviolet (UV) spectra of these polymers show an absorption band at 29,500 cm^?1 (? = 270) of n-π* character. The low temperature emission spectra of films of copolymers studied exhibit a less resolved vibrational structure and are bathochromically shifted with respect to those of polyacrylophenone and its styrene and methyl methacrylate copolymers. The emission decay is slightly nonexponential and has a lifetime of about 0.02 sec. Quantum yields of main chain scission in solution with 366-nm radiation are of the same order as those of the unsubstituted polyacrylophenone. Substitution by a strong electron-accepting group, in comparison with polyacrylophenone, influences the value of the quantum yield only a little but prolongs the lifetime of the lowest triplet state. This is also evident in an increase in the Stern–Volmer constant in passing from polyacrylophenone–naphthalene in benzene (68 mole^?1) to P4AcAP–naphthalene in dioxane (380 mole^?1). With biphenyl as a triplet quencher, the Stern–Volmer constants are low because of back transfer:     

Bioligand carriers based on methyl methacrylate copolymers with <Emphasis Type="Italic">N</Emphasis>-vinylformamide or glycidyl methacrylate

Emulsifier-free emulsion copolymerization of methyl methacrylate with N-vinylformamide and glycidyl methacrylate initiated by a cationic or anionic azoinitiator in the presence of dextran is used to produce monodisperse polymer particles with a developed multifunctional surface. As a result, monodisperse particles are obtained with a diameter of 350–660 nm, the surface layer of which contains, in addition to carboxyl groups, amino or epoxy groups. The conditions are determined for the formation of multifunctional hydrophilic particle surface via the hydrolysis of comonomer units and residual groups of initiators. The limiting values of bovine serum albumin chemisorption (2.4 and 1.0 mg/m² on the particles of methyl methacrylate copolymers with glycidyl methacrylate or N-vinyl formamide, respectively) indicate that the obtained particles have sufficient sorption capacity to be applied as carriers for immunoreagents.     

A Raman spectroscopic study of the low-frequency vibrations in anisole and anisole-d3

Low-frequency Raman spectra of solid anisole and of solid anisole-d₃ have been recorded at 130 K. The phenyl torsion observed at 148 cm^?1 is shifted to 133 cm^?1 upon deuteration of the methyl group. The twofold torsional barriers calculated from these frequencies are 4033 ± 110 cm^?1 and 4094 ± 123 cm^?1 indicating that coupling to other low-frequency modes in both cases is of the same order of magnitude. The methyl torsional mode was observed at 285 cm^?1 in the spectrum of solid anisole and at 183 cm^?1 in the spectrum of anisole-d₃. The threefold barriers calculated using these frequencies are 1847 ± 20 cm^?1 and 1465 ± 18 cm^?1 respectively. These barrier values indicate that the methyl torsion is coupled to another low-frequency mode. A doublet centered at 230 cm^?1 in anisole is shifted to 245 cm^?1 in anisole-d₃; it is proposed that this is due to a ring mode coupled to the methyl torsion. The splitting is interpreted as an example of Davydov splitting.     

PHOTOPOLYMERS: SYNTHESIS AND CHARACTERIZATION OF POLY(4-CINNA-MOYLPHENYL METHACRYLATE) WITH GLYCIDYL METHACRYLATE

Copolymers of 4-cinnmoylphenyl methacrylate (CPMA) with glycidyl methacrylate were synthesized in methyl ethyl ketone solution using benzoyl peroxide as initiator at 70 ± 1°C. They were characterized by UV, IR, ¹H-NMR, and ¹³C-NMR spectra. Their compositions were determined by ¹H-NMR technique. The monomer reactivity ratios were determined by the Fineman-Ross and Kelen-Tüdös methods. The molecular weights ([Mbar]_w and [Mbar]_n) of the polymers were determined by GPC technique. Thermogravimetric analysis of the copolymers were carried out in air. The T_g of the polymers were determined by differential scanning calorimetry. The photocrosslinking properties of the homo and copolymers were also discussed.     

Fullerene-C60, A New Effective Inhibitor of High-Temperature Thermooxidative Degradation of Methyl Methacrylate Copolymers

Fullerene-C₆₀ inhibits thermal and thermooxidative degradation of copolymers of methyl methacrylate with styrene, butyl acrylate, glycidyl methacrylate, and hydroxyethyl methacrylate.     

Alternating copolymerization through the complexes of conjugated vinyl monomers–alkylaluminum halides

A vinyl monomer that has the nitrile or carbonyl group conjugated to the C?C double bond, such as acrylonitrile, methyl acrylate, and methyl methacrylate, forms a complex with an alkylaluminum halide, and the complex reacts spontaneously with a hydrocarbon monomer such as styrene, propylene, or ethylene, giving a high molecular weight copolymer. The copolymers always contain the two monomer units in 1:1 ratio. Thus styrene, copolymerized with methyl acrylate or methyl methacrylate in the presence of ethylaluminum sesquichloride in homogeneous toluene solution, gives such an equimolar copolymer regardless of the initial monomer compositions. The NMR spectra of these copolymers are distinctly different from those of the equimolar copolymers obtained with azobisisobutyronitrile as initiator and have simpler and well separated patterns. The copolymers and the corresponding radical copolymers appear to be amorphous, judged by their x-ray diffraction patterns and their differential thermal analyses. Their infrared spectra resemble each other very closely. Hence, the difference in the NMR spectra may be ascribed to the matter of the sequence distribution. The infrared spectrum of ethylene–methyl acrylate copolymer shows no absorption near 720 cm.^?1 due to the methylene sequence arising from ethylene–ethylene linkage. These experimental data lead to the inference that the equimolar copolymers obtained in this work may have an alternating sequence.     

Investigation of infrared calibration methods for application to the study of methyl methacrylate polymerization

Infrared spectroscopy has been used to monitor the polymerization of methyl methacrylate. Concentrations of methyl methacrylate in the reaction mixture were determined by use of three calibration methods. Classical quantitative analysis was used to measure the height of the stretching vibration bands of the vinyl group at 1639 cm^–1. A calibration procedure using the considerably higher intensity of the C = O stretching vibration band of the carbonyl ester group at 1725 cm^–1 seemed useful only for high concentrations of methyl methacrylate, i.e. at the beginning of reaction, because this band overlaps that of poly(methyl methacrylate). Use of second-derivative spectra and measuring their values at 1725 cm^–1 enabled estimation of ten times lower concentrations of methyl methacrylate the calibration using the band from the vinyl group.     

Copolymers of methyl methacrylate and fluoroalkyl methacrylates: Effects of fluoroalkyl groups on the thermal and optical properties of the copolymers

Fluoroalkyl methacrylates, 2,2,2‐trifluoroethyl methacrylate ( 1 ), hexafluoroisopropyl methacrylate ( 2 ), 1,1,1,3,3,3‐hexafluoro‐2‐methyl‐2‐propyl methacrylate ( 3 ), and perfluoro t‐butyl methacrylate ( 4 ) were synthesized. Homopolymers and copolymers of these fluoroalkyl methacrylates with methyl methacrylate (MMA) were prepared and characterized. With the exception of the copolymers of MMA and 2,2,2‐trifluoroethyl methacrylate ( 1 ), the glass transition temperatures (T_gs) of the copolymers were found to deviate positively from the Gordon‐Taylor equation. The positive deviation from the Gordon‐Taylor equation could be accounted for by the dipole–dipole intrachain interaction between the methyl ester group and the fluoroalkyl ester group of the monomer units. These T_g values of the copolymers were found to fit with the Schneider equation. The fitting parameters in the Schneider equation were calculated, and R² values, the coefficients of determination, were almost 1.0. The refractive indices of the copolymers, measured at 532, 633, and 839 nm wavelengths, were lower than that of PMMA and showed a linear relationship with monomer composition in the copolymers. 2 and MMA have a tendency to polymerize in an alternating uniform monomer composition, resulting in less light scattering. This result suggests that the copolymer prepared with an equal molar ratio of 2 and MMA may have useful properties with applications in optical devices. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4748–4755, 2008     

Some 1-substituted quaternary imidazolium compounds and related polymers: Qualitative and quantitative infrared analysis

It was found that 1-substituted quaternary imidazolium compounds show some characteristic infrared (IR) activity. On quarternization of 1-substituted imidazoles strong absorption bands appeared at about 1150 and 1550 cm^?1 in the IR spectra of these compounds. The band at 1150 cm^?1 was assigned to the position 2 C?H bending mode and the 1550 cm^?1 band was attributed to a ring vibration mode of the quaternary imidazolium compounds. The concentration of the quaternary imidazolium units in a polymer can be determined by measuring the intensity of the absorption bands at 1150 or 1550 cm^?1 in relation to another suitable absorption band of the spectrum.     

Infrared spectroscopy of ethylene–vinyl chloride copolymers

This paper continues an investigation into the ethylene–vinyl chloride copolymers prepared by partial reduction of poly(vinyl chloride). The infrared spectra of the copolymers have been obtained and the individual resonances assigned. Each infrared band has been quantitatively analyzed in terms of peak position (cm^?1) and intensity, and correlations with the sequence microstructure (dyad, triads, etc.) have been determined. The infrared resonances have been found to be sensitive to long sequences; i.e., (V)_x or (E)_x where x ≥ 10. Sequences of up to 10–15 monomer units were seen to affect the position (cm^?1) and intensity of C? H stretching and bending frequencies. Methylene rocking bands between 850 and 700 cm^?1 were observed to be sequence dependent with ? V(E)_xV? resonanting at 860, 750, or 730 cm^?1 for x = 0, 1 and 2, or ≥3, respectively. The C? Cl stretching resonances, which are well known for their conformational complexity in pure PVC, were found to be dominated by sequence length effects reducing to two bands at 665 and 610 cm^?1 characteristic of and isolated ? CH? Cl unit in a long methylene chain.     

Confirmation of the presence of imine bonds in thermally cured polyimides

Model compounds for imines formed during the thermal curing of short chain polyimides have been synthesized and characterized. These compounds have imine bonds (C?N) formed by the nucleophilic attack of primary amines on imide carbonyls. The C?N stretching mode appears at 1649–1664 cm^?1 in the Raman and infrared spectra of these compounds and the band assigned to the carbonyl mode in an imide ring with an imine bond appears near 1740 cm^?1. These compounds have been prepared and characterized to verify the conclusions of a previously reported study in which bands observed in thermally cured short chain polyimides at 1656 and 1742 cm^?1 were assigned as the C?N and associated C?O modes, respectively. It has also been confirmed that the C?N stretching mode in the imide model compounds is inherently IR weak and can only be seen if the concentration of imine species is high. © 1993 John Wiley & Sons, Inc.     

Low‐energy excitations in stressed poly(methyl methacrylate)

Raman study of flexure stressed poly(methyl methacrylate) (PMMA) plates at the frequency range of libration mode (80 cm⁻¹), boson peak (14 cm⁻¹), and quasi‐elastic light scattering (QLS) (below 20 cm⁻¹) is presented. The reversible changes in the vicinity of the Rayleigh line were attributed to partial disturbance of the midrange order due to stress‐induced redistribution of random fluctuations of orientation. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1133–1136, 2000     

Preparation,Characterization and Properties of Cellulose Acetate-Grafted-Poly(glycidyl methacrylate) Copolymers

The cellulose acetate-grafted-poly(glycidyl methacrylate) copolymers were synthesized successfully by free radical polymerization. The resulting copolymer was characterized by proton nuclear magnetic resonance (¹H-NMR), solid-state ¹³C-NMR, Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). The crystallization behavior, thermal properties, specific particle surface area, moisture sorption behavior of the modified cellulose acetate were investigated by wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) method and Dynamic Vapor Sorption (DVS) instrument. It was found that the poly(glycidyl methacrylate) (PGMA) grafting was effective in improving the water adsorption of cellulose acetate (CA) changing the specific surface area, and reducing the T_g of copolymers.     

Synthesis and characterization of random and block copolymers with pendant rhenium diimine complexes by controlled radical polymerization

We report the polymerization of rhenium‐containing methacrylates by atom transfer radical polymerization. The structure of the monomer was confirmed by X‐ray crystallography, which showed the bulkiness of the metal‐complex moiety. The rhenium complexes were polymerized in the presence of copper(I) bromide, 1,1,4,7,7‐pentamethyldiethylenetriamine, and methyl 2‐bromopropionate. They were copolymerized with methyl methacrylate in different monomer ratios. An ABA triblock copolymer was also synthesized with poly(methyl methacrylate) as the macroinitiator. When 2,2′‐bipyridine was used as the ligand for the copper catalyst in the polymerizations, it underwent a ligand exchange process with the iminopyridine ligand in the monomer. The neutral rhenium complex in the homopolymers and copolymers could be converted into ionic forms by the replacement of the chloride with an imidazole ligand, and the solubility of the resulting ionic polymers was greatly enhanced. The photosensitizing properties of the doped and undoped polymer films were investigated by the measurement of the photocurrent response under an externally applied electric field. The photoconductivities of the polymers were approximately 10^?12–10^?13 Ω^?1 cm^?1. The experimental quantum efficiencies were simulated with Onsager's theory, and they showed that the initial quantum yield and thermalization distance were 10^?3 and 1.7 nm, respectively. Transmission electron microscopy showed that the rhenium complexes aggregated to form domains with dimensions of approximately 20–30 nm. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1292–1308, 2005     

Errata

The π → π* absorption spectrum of thioformaldehyde has been recorded at relatively high pressures and path lengths. The system is quite extensive and in H₂CS displays a progression of bands in an interval of 476cm^?1 which can be followed out to ν′ = 12. This is assigned to the ν′₃ CS stretching mode. A second weaker set of bands is assigned to 2ν′₄ the out-of-plane bending mode. The 725 cm^?1 interval observed here compared to the 711 cm^?1 value of the ã state leads us to the conclusion that the barrier to inversion is less than 50 cm^?1.