Film‐formation property of vinylidene chloride‐methyl methacrylate copolymer latex. I. Effect of emulsion‐polymerization process

Changes in minimum film‐formation temperature (MFFT) during storage of latexes prepared from 91:9 wt % vinylidene chloride (VDC)‐methyl methacrylate (MMA) monomer mixture by seeded batch and seeded semicontinuous emulsion polymerization were investigated, with attention centered on polymer‐crystallization behavior during storage in the dispersed state. MFFT of latex prepared by the seeded batch process rose to 47 °C, whereas that of latex prepared by seeded semicontinuous process remained below 14 °C with storage at 20 °C for 12 weeks. Infrared absorption of latexes in the dispersed state and wide‐angle X‐ray diffraction of powder polymers obtained by lyophilization of fresh and stored latexes both indicated a much greater increase in polymer crystallinity during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Analysis of the copolymer composition drift calculated from reactivity ratios and ¹H NMR analysis indicated a wider sequence distribution and longer VDC sequences in polymer prepared by the seeded batch process than in polymer prepared by the seeded semicontinuous process. This explained the higher rate of crystallization during storage with latex prepared by the seeded batch process than with that prepared by the seeded semicontinuous process. Rising crystallinity during storage in the dispersed state is believed to have caused the MFFT rise. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 939–947, 2002     

Etude des copolymeres (ethylene-hexene-1) par resonance magnetique nucleaire du proton et du carbone 13

Ethylene 1-hexene copolymers obtained by catalytic polymerization have been examined by ¹H and ¹³C NMR. Copolymer compositions have been determined by ¹H NMR and i.r. and the sequence distributions for 1-hexene by ¹³C NMR. Variations of the copolymer microstructure have been related to the experimental conditions for copolymerization.     

The effects of overall composition and monomer sequence distribution on the infrared carbonyl stretching frequencies of ethylene–vinylacetate and styrene–vinylacetate copolymers

The vinyl acetate centered triad fractions of some free radically prepared ethylene–vinyl acetate and styrene–vinyl acetate copolymers have been determined from the patterns of vinyl acetate methine carbon peaks in their ¹³C nuclear magnetic resonance (NMR) spectra. The positions and shapes of the carbonyl bands in the infrared (IR) absorption spectra of the copolymers recorded in chloroform are shown to depend on the compositions of the copolymers and on the proportions of the various vinyl acetate centered triads. Infrared absorption measurements may thus be used in part to characterize the monomer sequence distributions of these copolymers.     

Random-coil dimensions and dipole moments of propylene–vinyl chloride copolymers

Mean-square unperturbed dimensions 〈r²〉₀ and dipole moments 〈μ²〉 have been calculated for propylene–vinyl chloride copolymers by means of rotational isomeric state theory. The calculations indicate that for these chain molecules 〈mu;²〉 is much more sensitive to chemical sequence distribution than is 〈r²〉₀, a conclusion in agreement with results of previous studies of ethylene–propylene copolymers and styrene-substituted styrene copolymers. In the case of propylene–vinyl chloride chains, both 〈r²〉₀ and 〈μ²〉 are most strongly dependent on chemical sequence distribution in the case of copolymers which are significantly syndiotactic in stereochemical structure. At equimolar chemical composition, increase in average chemical sequence length generally increases 〈r²〉₀ but decreases 〈μ²〉. Under some conditions, values of these statistical properties go through a minimum with increase in the reactivity ratio product r₁r₂, thus complicating the use of experimental values of these properties in the characterization of chemical sequence distributions in these copolymers.     

Synthesis of silicone–acrylate copolymer latexes and their film properties

Emulsion copolymerization of silicones (octomethyl tetracyclosiloxane, D₄ and methacryloxypropyl trimethoxy silane, MATS) and acrylics was carried out using three different polymerization processes: semicontinuous monomer emulsion addition, batch and initiator solution addition. Results showed that only the semicontinuous process led to a stable latex with monodisperse particles. Various polymerizations were carried out through this process with varying silicone/acrylic ratios and MATS content. Films were obtained from different latexes: their properties are significantly influenced by silicone and MATS contents in copolymers.     

Reactivity Ratios and Sequence Distribution Characterization by Quantitative 13C NMR for RAFT Synthesis of Styrene‐Acrylonitrile Copolymers

The kinetics and reactivity ratios of styrene‐acrylonitrile (SA) copolymerization have been studied extensively in bulk and in a variety of solution media using conventional free radical polymerizations (FRPs). Due to the significant difference in the two reactivity ratios for this monomer pair, at certain feed ratios the copolymers display composition drift with conversion due to monomer depletion. In this study, the kinetics of SA copolymerization using Reversible Addition‐Fragmentation Chain Transfer (RAFT) has been studied in bulk at 80 °C. The reactivity ratios for the terminal model were calculated from the comonomer sequence distributions for the RAFT process at low conversion for nine different compositions and found to be in the same range as those reported for conventional FRP of SA. The changes in the composition and sequence distribution with conversion were studied for three feed compositions. The copolymers show compositional drift with conversion, except at the azeotropic composition, and match the predictions from the reactivity ratios obtained at low conversion. From quantitative ¹³C NMR the triad distributions of these copolymers were estimated and found to match the predicted triad distributions as conversion increased. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 919–927     

Investigation of the intramolecular structure of styrene–ethylmethacrylate copolymers by 1H- and 13C-NMR: Reassignment of 1H-NMR spectra

The compositions and sequence distributions of homogeneous styrene (S)–ethyl methacrylate (E) copolymers, obtained by low conversion solution polymerization have been studied by ¹H- and ¹³C-NMR. A new set of peak triad assignments was proposed for the δ 2.1–4.2 ppm region in the ¹H-NMR spectrum, whereby the reactivity ratios of r_S = 0.59 and r_E = 0.50 were used to establish this new assignment. The EEE and SSS blocks, present in these copolymers, have a high degree of syndiotacticity (σ_EE = 0.23, σ_SS = 0.39), whereas the ESE units are exhibiting a slight tendency toward isotacticity (σ_ES = 0.66).     

13Carbon nuclear magnetic resonance of ethylene–propylene–1‐decene terpolymers

Many studies have been reported on the ¹³C NMR characterization of ethylene–α‐olefin copolymers, but only a few have been reported on terpolymers. The incorporation of an α‐olefin into the polyethylene chain changes the structure and, consequently, the properties of the polymer obtained. Looking for new products, we obtained a series of ethylene–propylene–1‐decene terpolymers with the metallocenic system rac‐ethylene bisindenyl zirconium dichloride/methylaluminoxane. We performed a complete ¹³C NMR characterization of these terpolymers qualitatively and quantitatively. Here we present a detailed study of the ¹³C NMR chemical shifts, triad sequence distributions, monomer average sequence lengths, and reactivity ratios for these terpolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2531–2541, 2003     

Acrylonitrile–4-vinylpyridine copolymers effect of comonomer sequence distribution on properties

Acrylonitrile–,4-vinylpyridine copolymers were prepared in chloroform solution at 60°C with AIBN as initiator. Copolymer compositions were determined from their 15.01-MHz ¹³C-NMR spectra. Reactivity ratios of r_AN = 0.093 and r_4VP = 0.32 were calculated by the Kelen and Tudos method. The run number, number-average sequence lengths, and monomer sequence distributions were also calculated. The T_g values of the copolymers, their dye uptake, and degree of alkaline hydrolysis were influenced by the overall copolymer composition but particularly by the monomer sequence distribution in the copolymers.     

Copolymerization of isobutylene with 1,4-13C-isoprene

Copolymers of isobutylene with 1,4-¹³C-isoprene have been prepared in methyl chloride solvent at ?90 to ?50°C using aluminum chloride and organoaluminum halide initiators. The examination of these copolymers containing 0.5 to 3.0 mol % of the diolefin by ¹³C-NMR has given new information about the mechanism of the copolymerization. It appears that every macromolecule ends in an isoprene derived unit; that chain transfer to monomer by an isoprene-derived propagating carbocation is the dominant chain breaking process. The copolymer triad sequences have been unambiguously assigned and analyzed in both batch and continuous stirred tank reactor copolymers. The relative concentrations of the triads agree with those predicted by published reactivity ratios.     

Determination of microstructure and glass-transition temperature of acrylonitrile-methyl acrylate copolymers by 13C-NMR spectroscopy

Acrylonitrile-methyl acrylate (A/M) copolymers of different monomer compositions were prepared by bulk polymerization using free radical initiator (benzoyl peroxide). Copolymer compositions were determined by elemental analyses and comonomer reactivity ratios were determined by the nonlinear least squares errors-in-variables methods (EVM). Terminal and penultimate reactivity ratios have been calculated using the observed monomer triad sequence distribution determined from ¹³C{¹H}-NMR spectra. The triad sequence distribution was used to calculate diad concentrations, conditional probability parameters, number-average sequence lengths, and run number in the copolymers. The observed triad sequence concentrations determined from ¹³C{¹H}-NMR spectrum agreed well with those calculated from reactivity ratios. Glass transition temperatures (T_g) of various copolymers determined from DSC gave good agreement with those obtained from NMR. © 1992 John Wiley & Sons, Inc.     

Water-Soluble Copolymers. XIX. Copolymers of Acrylamide with Sodium 3-(N-Propyl)acrylamido-3-Methylbutanoate: Synthesis and Characterization

The copolymerization of acrylamide (AM) with sodium 3-(N-propyl)acrylamido-3-methlbutanoate (NaPAMB) has been studied in the range from 40 to 90% AM in the feed. The copolymer compositions have been determined from elemental analysis and ¹³C NMR. Reactivity ratio studies have been performed, and the value of r₁r₂ determined to be 0.36. The molecular weights, as determined by low-angle laser light scattering of the copolymers, were found to decrease sharply with increasing NaPAMB content, and were in the range 0.5–7.0 × 10⁶. The copolymer microstructures, including mean sequence length distributions, were calculated from the reactivity ratios. Knowledge of polymer composition, micro-structure, and molecular weight is utilized for assessment of structure/dilute solution property relationships reported in a subsequent paper in this series.     

19F- and 1H-NMR spectra of tetrafluoroethylene–propylene copolymers

High resolution 94-MHz ¹⁹F- and 100-MHz ¹H-NMR spectra were measured on a series of tetrafluoroethylene (TFE)-propylene (P) copolymers having a range of composition (TFE/P molar ratio = 37/63–55/45) and polymerized at different temperatures (?23, 25 and 65°C). The spectra were analyzed in relation to copolymer compositions. The assignment of ¹⁹F resonance in terms of tetrads proposed previously was confirmed, and the tentative assignment of ¹H resonances was proposed in terms of triads. The spectra thus interpreted revealed the sequence distribution of the copolymers. Copolymer compositions calculated from NMR spectra and elemental analysis agreed rather well with each other. Monomer reactivity ratios were calculated from the sequence distributions and compared with those obtained from the elemental analysis. It was observed that highly alternating copolymers are obtained in this system over a wide range of monomer composition at lower temperatures and that a deviation from alternancy increases slightly with rising polymerization temperature.     

Controlling monomer sequence distribution in RAFT polymerization of styrene and acrylic acid

Continuous and semicontinuous RAFT copolymerization was first applied to synthesize well-defined copolymers of styrene and acrylic acid. The obtained copolymers have a different monomer sequence distribution due to different ways of adding acrylic acid to the reaction medium.     

Thermal degradation of vinyl alcohol/vinyl acetate copolymers. III. Study of the reaction products

The thermal decomposition of vinyl alcohol/vinyl acetate copolymers have been studied at p = 10⁻²–10⁻⁴ Torr and T = 0–600°C. The decomposition products (solids, liquids, and gases) have been characterized by infrared (IR) and ultraviolet (UV) spectroscopy, gas chromatography, vapor pressure osmometry, and elemental analysis. It has been ascertained on the basis of the obtained data that the decomposition mechanism of the vinyl alcohol/vinyl acetate copolymers depends on the chemical composition and sequence distribution of comonomers.     

INTERPOLYMER ASSOCIATION OF ACRYLAMIDE COPOLYMERS WITH POLY(ETHYLENEIMINE): STABILITY,THERMODYNAMIC PARAMETERS,AND THEIR CORRELATION WITH THE COPOLYMER MICROSTRUCTURE

Acrylamide/vinyl acetate and acrylamide/vinyl propionate copolymers were prepared by solution polymerization using benzoyl peroxide as the initiator. The copolymer composition was determined from the percent nitrogen in the copolymers.

The stability constants and related thermodynamic parameters (e.g., ΔG°, ΔH°, and ΔS°,) of the interpolymer complexes with Poly(ethyleneimine) were determined by using Osada's method. These parameters have been correlated with the sequence distribution of monomer units in the copolymer chains which were obtained from ¹³C{¹H} NMR spectroscopy. The sequence distribution of the comonomer units in the copolymer chains influence the association between the copolymers and the polyelectrolyte which is reflected on the stability of the interpolymer complexes.     

Determination of the reactivity parameters for the copolymerization of butyl acrylate with vinyl acetate

The composition of vinyl acetate–butyl acrylate copolymers obtained with batch emulsion polymerization have been studied by ¹H-NMR. Using the integrated copolymerization Meyer–Lowry equation, the apparent reactivity ratios of the two monomers were calculated as 10.67 for r₁, the reactivity ratio of butyl acrylate (BA), and 0.024 for r₂, the reactivity ratio of vinyl acetate (VAC). These results were compared with those obtained by other methods.     

A study of the copolymerization of hydroxyethyl methacrylate and tetrahydrofurfuryl methacrylate

The free radical copolymerizations of hydroxyethyl methacrylate and tetrahydrofurfuryl methacrylate have been investigated at 50°C. The compositions of polymers prepared at low conversions have been determined using ¹³C-NMR, and the glass transition temperatures determined by DSC. The copolymerizations were found to be best described by a terminal model with reactivity ratios of r_H = 1.79 and r_T = 0.76. The triad fraction sequence distributions have been calculated based on the terminal model and the calculated reactivity ratios. The glass transitions have been fitted to the Gordon–Taylor equation. The best value of the Gordon–Taylor constant was found to be k_H = 1.42 ± 0.2, indicating nonideal mixing of the two monomer components in the copolymers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3730–3737, 1999     

NMR analysis of the microstructure of poly(methyl acrylate-co-N-vinylcarbazole)

The microstructure of a series of high conversion copolymers of methyl acrylate (MA) and N-vinylcarbazole (NVC) was characterized by NMR. ¹H- and ¹³C-NMR spectra were assigned by comparison to the homopolymers and by using heteronuclear shift correlation spectroscopy. MA-centered triad distributions were obtained from the carbonyl carbon. Distributions of NVC sequences were determined from aromatic carbons 1 and 8a, and aromatic proton 1 These experimentally determined sequence distributions were compared to those calculated from reactivity ratios approximated from the copolymer compositions. Agreement was very good for low NVC content copolymers. Three signals were particularly useful in providing rapid assessment of the distribution of NVC units within low NVC content copolymers: proton 1 and carbon 1 of NVC and the carbonyl carbon of MA. © 1992 John Wiley & Sons, Inc.     

Study of the thermal behaviour of some transition metal acrylate-styrene copolymers

The processes of thermal destruction of copolymers of styrene with zinc, cobalt, nickel and copper acrylates have been studied by TG and the temperature characteristics have been determined. While the thermal stability of zinc-containing copolymers increases at higher metal contents, that of other metal-containing copolymers decreases and, depending on the metal, changes in the sequence Co > Ni > Cu. The kinetic parametersn, E _a ,Z and ΔS have been determined by the Horowitz-Metzger method and discussed. The resultingE _a sequence is in agreement with the observed sequence of thermal stability of the copolymers. The entropy factor suggests thermodynamic hindrance in the decomposition of copolymers of low thermal stability and a preference for the decomposition of copolymers of high thermal stability.