Diisopropyl Fumarate Research Articles

Dielectric relaxation of binary systems of some disubstituted fumarates with acrylonitrile and vinylacetate in CCl 4 solutions

The dielectric absorption of binary mixtures of some dialkyl fumarates namely dimethyl fumarate (DMF), diethyl fumarate (DEF), diisopropyl fumarate (DIPF), dinonyl fumarate (DNF), and didodecyl fumarate (DDF) with either acrylonitrile (AN) or vinylacetate (VA) with different mole fractions in dilute solutions of carbon trachloride has been measured in the microwave region (0.2–18 GHz). The data were analyzed by the sum of two Debye terms (or even one term). The relaxation times obtained were found to describe the orientation of the molecule as whole and studied as a function of the mole fraction. Some deviation from linearity was detected This deviation is discussed in terms of the molecular interaction which is expected to take place between the investigated fumarates with acrylonitrile and vinylacetate. The systems contain vinylacetate were found to possess higher interaction when compared with those of acrylonitrile. This presumption finds further justification through the values of equilibrium constant K by means of the dielectric polarization measurements.

Evaluation of chain rigidity of poly(diisopropyl fumarate) from light scattering and viscosity in tetrahydrofuran

Poly(diisopropyl fumarate) (poly(DiPF)) was prepared by radical polymerization in bulk or in benzene with an azo initiator at 60°C, and fractionated with tetrahydrofuran (THF) or methanol as the solvent and water as the non-solvent. The selected nine fractions with a relatively narrow molecular weight distribution were used for the viscometric, light scattering and gel permeation chromatography experiments. The light scattering and viscosity studies using several kinds of solvents revealed that the intrinsic viscosity of poly(DiPF) changed less sensitively to the nature of the solvent used, in contrast with the second virial coefficient which was strongly dependent on the solvent. The Mark–Houwink–Sakurada equation was determined as follows: [η]=5.18×10−4Mw0.98 in cm3/g in THF at 30°C. The persistence length (q) of poly(DiPF) was evaluated from the viscosity data in THF using the Bohdanecký plot. The q and the molecular weight per unit contour length (ML) were 11 nm and 1340 nm−1, respectively. These values were compared with those for typical semiflexible polymers reported in literature.

Effects of solvent as an electron-pair acceptor on propagation reactions during radical polymerization and copolymerization of polar vinyl monomers

We carried out radical homopolymerization and copolymerization in various kinds of solvents at 60°C by using diisopropyl fumarate (DiPF) and methyl methacrylate (MMA) as electron-accepting polar monomers and styrene (St) and vinyl benzoate (VB) as electron-donating monomers. The highest polymerization rate was observed in the polar and electron-pair accepting solvents, such as 2,2,2-trifluoroethanol for the homopolymerization and copolymerization of these monomers. It has been revealed that the polymerization rate is correlated to the electron-pair–accepting property of the solvent used, rather than the polarity in the linear free energy relationship. We have demonstrated the validity of the acceptor number as the index for interpreting the interaction of the solvent with the monomer and the propagating chain end. The monomer reactivity ratios were determined for the St–DiPF, VB–DiPF, and St–MMA copolymerizations. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2803–2814, 1999

Electro-Optical Effect Without Hysteresis for (Polymer/Liquid Crystal) Composite Films

Phase-separation behavior of the composite films composed of polymer of a three dimensional network and low molecular weight liquid crystals (LCs) embedded in the network was studied on the basis of the evolution of optical heterogeneity in a casting solution during a film formation process and the morphology of the polymer networks. The electro-optical properties of the composite films based on electric field controlled light scattering were strongly dependent on the size of LC domains which was controlled by the solvent evaporation rate. When poly(diisopropyl fumarate), which is incompatible with the LC, was used as the matrix polymer, no electro-optical hysteresis was detected, while considerable electro-optical hysteresis was done for the composite film consisting of poly(methyl methacrylate), which is fairly compatible with the LC. However, when poly(methyl methacrylate) with high molecular weight (996k) was used as the matrix polymer, hysteresis decreased due to a decrease of compatibility.

Dielectric relaxation of dialkyl fumarates monomers homopolymers and copolymers in dilute solutions

Abstract The dielectric absorption of some disubstituted ethylenes (dialkyl fumarates) namely dimethyl fumarate (DMF), diethyl fumarate (DEF), diisopropyl fumarate (DIPF), dicyclohexyl fumarate (DCHF), dicyclohexyl maleate (DCHM), dinonyl fumarate (DNF), didodecyl fumarate (DDF) and dicetyl fumarate(DCF) has been measured in the microwave region 0.2–18 GHz. The measurements were carried out at 20°C. The solvent used in all cases was CCl 4 and the concentration does not exceed 0.003 mole fraction. The data obtained for the specific absorption Aϵ/x were analyzed using Debye equation into one or even more than one relaxation time. The results were interpreted in terms of dipole reorientation by molecular and intermolecular rotation. Dielectric measurements were also carried for some dialcyl fumarate polymers and copolymers in CCl 4 solutions at 30 °C. The dielectric data revealed the existence of three distinct absorption regions related to the main chain and its related motions.

Thermal stability of nano-structure in polymeric Langmuir-Blodgett films studied by the energy transfer method

The thermal stability of Langmuir-Blodgett (LB) films of poly(vinyl octanal acetal) (PVO), poly(diisopropyl fumarate) (PDiPF), poly(dicyclohexyl fumarate) (PDcHF) and poly(isobutyl methacrylate) (PiBMA) has been investigated. The energy transfer method was employed to study the structural relaxation of these films by heating, in which a pair of energy-donating and -accepting PVO layers were incorporated as the probes. In the temperature range between 30 and 120 °C, all these polymer LB films showed structural relaxation. A close relationship between the structural relaxation of polymer LB films and the glass transition temperature, T g , of the corresponding polymer bulk was observed. Although the fumarate polymers did not show clear T g in the temperature range observed, the structural relaxation of LB films was also observed and this was attributed to the local motions of the polymer chain; the transition was also detected as a small signal of DSC. After the thermal treatment, the miscible LB films showed an increase of energy-transfer efficiency expected for a random distribution of the chromophores, whereas immiscible polymer LB films induced a further increase in energy-transfer efficiency due to the phase separation of the probing layers from the examined layers after the thermal treatment. In the case of PiBMA-LB film, the rapid progress of phase separation was observed at temperatures higher than T g . In PDiPF-LB and PDcHF-LB films, the phase separation proceeded gradually because the segment motions of the polymer were not so vigorous in this temperature range. The effects of molecular weight and the initial spatial arrangement of LB layers indicated that the relaxation process is governed by the rate of diffusion of each polymer.

Low Voltage Light Switching of Hybrid-Type Cell Composed of (Polymer/Liquid Crystal) Composite System

(Polymer/liquid crystal: LC) composite films consisting of a continuous LC phase embedded in a three-dimensional network of polymer matrix were prepared by a solvent-induced phase separation method. The (composite film/LC/composite film) hybrid laminar cell was applied for a novel light switching device by using the (poly(diisopropyl fumarate): Pdi-iPF/LC) composite systems as the composite films. A new type of cell geometry was proposed to achieve a low voltage drive for the light scattering-light transmission switching. The distribution ratio of an applied external electric field in the composite film layer and the LC one was calculated based on the series-connected dielectric composite model. The magnitude of an imposed electric field to the composite film layer was larger than an applied external one in the case that the absolute magnitude of the complex dielectric constant of LC was larger than that of the composite film. A remarkably low voltage driving for the electro-optical switching with reasonably fast rise and decay response times was realized for the new hybrid cell.

Synthesis and characterization of copolymers of dialkyl fumarates

Radical copolymerisations of di- iso-propyl fumarate (DiPF) with di- n-propyl fumarate (DnPF), di- n-butyl fumarate (DnBF), di- n-amyl-fumarate (DnAF), di- n-heptyl fumarate (DnHF) and di-ethyl-hexyl fumarate (DEHF) were studied. The reactivity ratios for the following monomer pairs, DiPF/DnPF, DiPF/DnBF, DiPF/DnAF, DiPF/DnHF and DiPF/DEHF, were determined. The structures of the copolymers were examined by 1H-NMR and WAXD. Some properties of the copolymers were examined.

Phase-Separation Behavior and Electro-Optical Properties for (Polymer/Liquid Crystal) Composite Films

AbstractDominant factors that control the aggregation structure and electro-optical properties were presented for (polymer/liquid crystal) composite films prepared by a solvent cast method from homogeneous solutions. Phase-separation behavior of the composite films consisting of a three dimensional polymer network and low molecular weight liquid crystals (LCs) embedded in the network was studied by evaluating the development of optical heterogeneity in the casting solution during film formation and by observing the morphology of the polymer networks. It was confirmed from light scattering studies of the casting solution during solvent evaporation that the phase-separated structure of polymer and LC was formed through spinodal decomposition. The resultant size of the LC domain in the composite film was controlled by regulating the solvent evaporation rate. The morphology of the polymer network in the composite film was also strongly influenced by the solubility between the polymer and the casting solvent. The electro-optical properties based on field controlled light scattering of the composite film were strongly dependent on the size of the LC domain. Though the rise response time decreased, the decay response time increased with an increase in the size of LC domains in the composite film. When poly(diisopropyl fumarate), which is not compatible with the LC, was used as the matrix polymer, no electro-optical hysteresis was observed, while considerable electro-optical hysteresis was observed for the composite film consisting of poly(methyl methacrylate), which shows a certain compatibility with the LC.

Interfacial Interaction of Polymer/Liquid Crystal Molecules and Electrooptical Properties of their Composite Systems

Polymer/liquid crystal composite films were prepared from a solution of polymer and nematic liquid crystal (LC) by a solvent casting method. The phase-separated structure of the composite film was controlled by the solvent evaporation rate. The light-scattering profile of a poly(diisopropyl fumarate)/LC: 40/60 w/w solution during solvent evaporation exhibited a periodic structure, indicating that the phase-separated structure was formed by spinodal decomposition. The aggregation structure of the composite film was investigated with a scanning electron microscope (SEM). SEM observation of the composite film suggested the presence of periodicity and dual connectivity of polymer and LC phases. The faster the solvent was evaporated, the smaller the LC channel (domain) size in the composite film. The composite film, composed of poly(methyl methacrylate) (PMMA) and a nematic LC (E44) with a positive dielectric anisotropy, exhibited remarkable and reversible light-scattering-light-transmission switching, under t...

Synthesis of telechelic polymers through radical polymerization with a two-component iniferter system

A two-component iniferter system, consisting of an initiator and a chain transfer agent bearing the same functional group, is proposed for control of the chain-end structure of vinyl polymers. In this paper, 4,4′-azobiscyanovaleric acid (ACVA) and dithiodiglycol acid (DDGA) were used as initiator and chain transfer agent respectively, for polymerizations of some vinyl monomers to synthesize the polymers having a carboxyl group at both chain-ends. In the polymerizations of styrene (St) and vinyl acetate, the proposed two-component iniferter system was found to be effective for the synthesis of the telechelic polymers. On the other hand, the end-structure of the polymers could not be controlled efficiently in polymerizations of butadiene, methyl acrylate and methyl methacrylate; diisopropyl fumarate gave telechelic polymers with ACVA and DDGA. Polycondensation of the resulting telechelic poly(St) with polyethyleneglycol was carried out to obtain a block copolymer.

Radical polymerization and copolymerization of bis{3‐[tris(trimethylsiloxy)silyl]propyl} fumarate

AbstractRadical polymerization and copolymerization of bis{3‐[tris(trimethylsiloxy)silyl]propyl} fumarate (BSPF (1)) were investigated. The reactivity of BSPF in homopolymerization was found to be very low, and only low‐molecular‐weight poly(BSPF) was obtained in low yields. On the other hand, copolymerizations of BSPF with diisopropyl fumarate (DiPF) and di‐tert‐butyl fumarate (DtBF) proceed with moderate rates to give high‐molecular‐weight copolymers. The monomer reactivity ratios were determined to be as follows; r1 = 0,07, r2 = 0,87 for BSPF (M1) and DiPF (M2); r1 = 0,21, r2 = 0,67 for BSPF (M1) and DtBF (M2). The resulting copolymers are soluble in many common organic solvents. Tough and brittle films were obtained by solution casting of the copolymers of BSPF and DtBF. The copolymers exhibit excellent oxygen permeability.

Synthesis of substituted polymethylenes from acenaphthylene by radical polymerization and copolymerization

AbstractRadical polymerization of acenaphthylene (Ace) as a 1,2‐disubstituted ethylene was investigated. It was found that the polymerization rate (Rp) was expressed as follows: Rp = k[Ace]1.0[AIBN]0.68, and that the overall activation energy was 113 kJ/mol for polymerization with 2,2'‐azobisisobutyronitrile (AIBN) in benzene at 50–70°C. Poly(Ace) obtained was characterized by NMR spectroscopy and GPC. Some substituted copolymethylenes were also prepared by radical copolymerization of Ace with other 1,2‐disubstituted ethylenes, that is, maleic anhydride, diisopropyl fumarate, and N‐cyclohexylmaleimide. The monomer reactivity ratios were determined from comonomer–copolymer composition curves.

Radical polymerization of isopropyl tert‐butyl fumarate and maleate, and characterization of the resulting polymers

AbstractRadical polymerization of isopropyl tert‐butyl fumarate (iPtBF) and monomer‐isomerization radical polymerization of isopropyl tert‐butyl maleate (iPtBM) were investigated with 2,2′‐azobisisobutyronitrile as initiator in the presence and absence of morpholine (Mor) as isomerization catalyst. It was found that iPtBF gave high molecular weight polymers in high yield as previously observed for diisopropyl fumarate (DiPF) and di‐tert‐butyl fumarate (DtBF). It was confirmed that iPtBF produced by in situ monomer isomerization of iPtBM homopolymerized to give a polymer. Radical copolymerization of iPtBM with styrene in the presence and absence of Mor was also performed and monomer reactivity ratios obtained were compared. From the kinetic study of the isomerization of iPtBM, it was revealed that the isomerization rate showed first‐order dependence on the concentration of iPtBM and Mor, and that the apparent activation energy was 29.4 kJ/mol. On pyrolysis of the poly(iPtBF) at 180°C, isobutene and isopropanol were eliminated rapidly to yield polymer containing carboxyl groups and anhydrides. The pyrolytic behavior was different from that of a copolymer of DiPF with DtBF.

Meso and racemo Additions in Propagation for Radical Polymerization of Dialkyl Fumarates I. Stereoregularity of Poly(dialkyl fumarate)s

The polymerization temperature dependence of the stereochemical configuration of some poly(dialkyl fumarate)s as poly(substituted methylene) was investigated by the use of 13C NMR spectroscopy in order to clarify the propagation process in radical polymerization of dialkyl fumarates. The probability of meso addition (Pm) for polymerization of di-tert-butyl fumarate increased from 0.68 to 0.80, when the polymerization temperature decreased from 120°C to 0°C. On the other hand, it was revealed that Pm for dimethyl fumarate and diisopropyl fumarate decreased by the decreasing polymerization temperature, and that it was almost independent of the temperature for methyl tert-butyl fumarate. From the differences in activation enthalpies and entropies for meso and racemo additions, the effect of the ester alkyl groups on the propagation manner was discussed.

Determination of absolute rate constants for radical polymerization of diisopropyl fumarate based on a quantitative scavenge of propagating radical

During polymerization of diisopropyl fumarate (DiPF), the propagating poly(DiPF) radical was scavenged quantitatively by a stable free radical, because of its long-lived nature and high steady-state concentration. By addition of a known amount of 1,3,5-triphenylverdazyl to the polymerization mixture, the concentration of poly(DiPF) radical was determined to be 10 −5−10 −4 mol dm −3, which allowed the evaluation of the propagation rate constant ( k p) from the overall rate of polymerization: k p = 0.31 ± 0.07 dm 3 mol −1 s −1 at 30°C. The lifetime of the polymer radical was too long for a rotating sector experiment. The rate constant for bimolecular termination of the radical ( k t) was calculated from the decay of poly(DiPF) radical followed by the scavenger method: k t = 0.84 dm 3 mol −1 s −1. These rate constants, which are exceptionally small, are accounted for by the steric factor of the ester alkyl group accumulated along the polymer chain and extremely slow diffusion of the polymer radical. Because the termination rate determined is too slow to interpret the molecular weight of the polymer formed, primary radical termination is to be considered as an additional termination process in the actual polymerization.

Synthesis of high molecular weight poly(dialkyl fumarate)s bearing n-alkyl side chains from poly(di-tert-butyl fumarate) via olefin elimination and reesterification in a one-pot

High molecular weight poly(dialkyl fumarate)s bearing n-alkyl esters such as an octadecyl group were prepared efficiently from poly(di-tert-butyl fumarate) by the one-pot synthesis, i.e. both elimination of isobutene from the tert-butyl ester and the subsequent esterification were performed in a corresponding alcohol at 170–180°C in a one-pot without isolating poly(fumaric acid). The resulting polymers were characterized by IR and NMR spectroscopies and GPC. The polymers with various contents of an octadecyl group in the side chain were also obtained similarly from the copolymer of di-tert-butyl fumarate with diisopropyl fumarate.

Dilute solution properties of semiflexible poly(substituted methylenes): intrinsic viscosity of poly(diisopropyl fumarate) in benzene

La relation [n]=7,53•10 −6 •M 0,98 est etablie entre la viscosite intrinseque du polyfumarate en solution dans le benzene a 30 o C et sa masse moleculairie pour M<3•10 5 . La valeur de a obtenue (0,98) est la plus elevee obtenue pour un polymere vinylique; elle diminue lorsque la masse moleculaire augmente et depend de la nature des groupes alkyl (0,87 pour le poly(fumarate de diethyle))

Molecular characterization of poly(diisopropyl fumarate) by the absolute calibration method in molecular exclusion chromatography (GPC)

AbstractThe present work demonstrates that it is possible to obtain the parameters K and a of the Staudinger‐Mark‐Houwink relationship between the intrinsic viscosity [η] and the molecular weight M of a polymer by applying the absolute method of exclusion chromatography to samples of poly (diisopropyl fumarate). The procedure is based on deducing the relationship between molecular weight and elution volume V from chromatographic runs of a stoichiometrically labeled polymer sample with a broad molecular weight distribution. By using double detection it is possible to obtain the relationship f(V)/h(V) = M(V)/Mn = exp (A‐BV)/Mn where Mn is the osmotically determined number average of the molecular weight of the eluted polymer while f(V) and h(V) are the normalized elution curves obtained by the use of the polymer mass detector and the label detector respectively. A and B are the parameters of the calibration curve, i.e., the relationship between M and V which together with the intrinsic viscosity and the elution curves of several samples of the polymer allows us to obtain the relationship between [η] and M.The results have been verified with chromatographic data through the use of the universal calibration concept.

Relations between molecular aggregation state and mechanical properties in poly(diisopropyl fumarate)

The backbone chain of poly(diisopropyl fumarate) (PDiPF) has a high rigidity. PDiPF molecules are aggregated as a nematic liquid crystal-like structure in film cast from solution. The lateral extent of the liquid crystal-like order is evaluated to be ∼ 9 nm. The β absorption of loss modulus E″ appeared at 370 K in the film and is associated with the motion of bulky ester groups. The storage modulus E′ was ∼ 1 GPa below the β absorption temperature, whereas a relatively high value of ∼ 0.1 GPa was retained in the temperature range from 390–500 K, since the high rigidity of the backbone chain is kept.