Isomeric Polymers Research Articles

Synthesis, Characterization and Some Optical Properties of Poly(hexa-2,4-diynylene-1,6-dioxy)dinaphthoates Containing Polar Azo Dye

In order to study the effect of main-chain conformation on the second-order non-linear optical properties, two novel isomeric polymers, consisting of hexa-2,4-diynylene-1,6-dioxydinaphthoates main-chains containing a polar azo dye, Disperse Red 19, were synthesized and characterized. The 1,2- and 3,2-polymers had a T g of 134 and 143°C, respectively. Their spin-coated films were exposed to corona poling, and the orientation behavior was studied. The order parameters of the two polymers were similar, around 0.2. The 3,2-polymer underwent cross-linking during poling. Neither polymer did cross-link when irradiated by UV light during poling, indicating that their chemical structures are not apt to cross-link.

Effects of main chains on the second order nonlinear optical susceptibility of poled poly(dipropargyloxybenzoates) containing 2-[4-(2-chloro-4-nitrophenylazo)- N-ethyl-phenylamino]ethanol ( Disperse Red 13)

A series of isomeric polymers containing hexa-2,4-diynylene-1,6-dioxybenzoate group as the main chain and a polar azo dye ( Disperse Red 13) as in the side chain were synthesized, and their second order nonlinear optical responses were studied. The second order nonlinear coefficients, d 33 were found to be in the range of 50–90 pm/V. The nonlinear response ( d 33) with respect to the positions of main chain was found to be in the order; 3,5-( meta) > 3,4-( ortho) > 2,5- ( para) > 2,4-( meta), but the order of values d 33/ d 31 was 3,5-( meta) > 2,4-( meta) > 2,5- ( para) > 3,4 ( ortho). The higher response of the 3,5-polymer may be attributed to the symmetric substitution on the benzene ring, permitting the main chain conformation with less flexibility, as well as a higher Tg.

SECOND-ORDER NONLINEAR OPTICAL SUSCEPTIBILITIES OF POLY[(HEXA-2,4-DIYNYLENE-1,6-DIOXY)DIBENZOATES] CONTAINING AZO CHROMOPHORE DISPERSE RED 19 BY ELECTROABSORPTION SPECTROSCOPY

The second-order nonlinear optical susceptibilities χ(2) of two isomeric polymers containing an azo dye, Disperse Red 19, were determined by the first-order electroabsorption spectroscopy (EAS), and compared with values previously obtained by SHG measurements. The para-polymer was found to have higher susceptibility than the corresponding meta-polymer. χ(2) were found to be 5–6 × 10-8 esu, which are comparable to those obtained by the Maker Fringe method.

Miscibility in Blends of Isotactic/Syndiotactic Polystyrenes at Melt or Quenched Amorphous Solid State

AbstractSummary: Miscibility in amorphous phase and behavior in a crystalline phase of blends of two semicrystalline and isomeric polymers, isotactic polystyrene (iPS) and syndiotactic polystyrene (sPS), was probed. Optical and scanning electron microscopy results indicate no discernible heterogeneity in iPS/sPS blends in either melt state or rapidly quenched amorphous super‐cooled state, while the Tg behavior of the quenched amorphous blends shows an intimately mixed state of two polymer chains. The crystal forms of the blends were further analyzed to provide additional evidence of miscibility in the amorphous domain. The sPS in the iPS/sPS blends upon melt crystallization was found to predominantly exist as the more stable β‐form (rather than mixed β‐form and α‐form in neat sPS), which also suggests evidence of miscibility in the iPS/sPS blends. The melting behavior of semicrystalline sPS in the iPS/sPS mixtures was analyzed using the Flory‐Huggins approach for estimation of interactions. By measuring the equilibrium melting point of the higher‐melting sPS species in the sPS/iPS blends, a small negative value, for the interaction parameter (χ ≈ −0.11) was found. Further, by introducing a third polymer, poly(2,6‐dimethyl‐p‐phenylene oxide) (PPO), a ternary iPS/sPS/PPO blend system was also proven miscible, which constituted a further test for stable phase miscibility in the iPS/sPS blend. General nature of miscibility in blends composed of two crystalline isomeric polymers is discussed. Issues in dealing with blends of polymers of the same chemical repeat unit but different tacticities were addressed.X‐ray diffractograms for neat sPS and iPS/sPS blends, each having been isothermally crystallized at 245 °C for 4 h.magnified imageX‐ray diffractograms for neat sPS and iPS/sPS blends, each having been isothermally crystallized at 245 °C for 4 h.

A Comparison of Poly(ether imide)s with 3-Phthalimide and 4-Phthalimide Units: Synthesis, Characterization, and Physical Properties

Bis(ether anhydride)s with 3- or 4-phthalimide moieties were prepared by reacting 3- or 4-nitrophthalodinitrile, respectively, with several diols and converting the resulting bis(ether dinitrile)s to bis(ether anhydride)s. Selected dianhydrides were converted into poly(ether imide)s in a two-stage solution polymerization and imidization process. It was found that, in most cases, the dianhydrides with 4-phthalic anhydride units gave high-molecular-weight polymers with any of several aromatic diamines. In contrast, dianhydrides with 3-phthalic anhydride units gave, primarily, low-molecular-weight products. Examination of several low-molecular-weight products by electrospray-ionization mass spectrometry demonstrated that the products consisted of small oligomers, cyclic or linear according to the structure of the diamine. A series of high-molecular-weight polymers were prepared from 4,4‘-bis(4‘ ‘-aminophenoxy)biphenyl (BAPB) and each of several bis(ether anhydride)s with 3- or 4-phthalic anhydride units; the anhydrides had isopropylidine or hexafluoroisopropylidine units or ortho-methyl or ortho-tert-butyl substituents in the diol residues. These polymers were characterized in terms of their molecular weights and glass-transition temperatures. The gas permeabilities, positron annihilation, and dielectric relaxation behaviors of the polymers were investigated and their properties related to their molecular structures. Dielectric relaxation spectroscopy measurements indicate that, in this group of polymers, the rates of the local chain mobility are comparable and are able to facilitate gas diffusion. An apparent linear correlation between the permeation coefficients and free volume as determined by positron annihilation lifetime spectroscopy was observed with certain gases. Comparison of polymers with similar molecular structures indicated that isomeric polymers with 3- and 4-linked phthalimide units have similar properties and that the introduction of branched chains or fluorinated groups leads to an increase in the free volume and consequently increased permeability.

Back Cover: Macromol. Rapid Commun. 17/2006

Back Cover: Owing to a unique regiodifferentiating nature of an unsymmetric spirocyclic dianhydride, alternating copoly‐ (amide acid)s and copolyimides could be obtained in one‐pot. Constitutionally isomeric polymers were synthesized from common monomers by only changing the method of addition. Further details can be found in the article by K. Kudo,* T. Yoshizawa, T. Hamada, J. Li, S. Sakamoto, and S. Shiraishi on page 1430.

Efficient blue‐green‐emitting poly[(5‐diphenylamino‐1,3‐phenylenevinylene)‐alt‐(2,5‐dihexyloxy‐1,4‐phenylenevinylene)] derivatives: Synthesis and optical properties

AbstractNew poly(phenylene vinylene) derivatives with a 5‐diphenylamino‐1,3‐phenylene linkage (including polymers 2, 3, and 5) have been synthesized to improve the charge‐injection properties. These polymers are highly photoluminescent with fluorescent quantum yields as high as 76% in tetrahydrofuran solutions. With effective π‐conjugation interruption at adjacent m‐phenylene units, chromophores of different conjugation lengths can be incorporated into the polymer chain in a controllable manner. In polymer 2, the structural regularity leads to an isolated, well‐defined emitting chromophore. Isomeric polymer 3 of a random chain sequence, however, allows the effective emitting chromophores to be joined in sequence by sharing a common m‐phenylene linkage (as shown in a molecular fragment). Double‐layer light‐emitting‐diode devices using 2, 3, and 5 as emitting layers have turn‐on voltages of about 3.5 V and produce blue‐green emissions with peaks at 493, 492, and 482 nm and external quantum efficiencies up to 1.42, 0.98, and 1.53%, respectively. In comparison with a light‐emitting diode using 2, a device using 3 shows improved charge injection and displays increased brightness by a factor of ∼3 to 1400 cd/m2 at an 8‐V bias. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2307–2315, 2006

Lyotropic Lamellar Polysiloxanes with Isomeric Amphiphilic Side Chains

AbstractSummary: This paper presents the synthesis of two polymeric surfactants, consisting of a polysiloxane backbone with amphiphilic side chains of the nonionic oligo(ethylene oxide) type, and their phase behavior in aqueous solution, investigated by polarizing microscopy and deuterium NMR spectroscopy using D2O as a probe. Two different side chains, which are isomeric glycerol derivatives, were synthesized and attached to poly(methyl hydrogen siloxane) by a hydrosilylation reaction, resulting in a tail‐type and a mid‐type polysurfactant. The side chains of the tail‐type system are fixed at the end of the hydrophobic moiety, whereas the side‐chains of the mid‐type system are tethered to the polymer backbone by a short spacer close to the hydrophilic‐hydrophobic junction of the amphiphile. Both polymers form a lamellar phase in aqueous solution over a wide range of concentrations, whereas the side chain precursors do not form lyomesophases. The cloud curve and the lamellar region are observed at lower temperatures in the mid‐type polysurfactant.Structures of the isomeric polymers forming lamellar phases.magnified imageStructures of the isomeric polymers forming lamellar phases.

Isomer Structure−Optical Property Relationships for Naphthalene-Based Poly(perfluorocyclobutyl ether)s

Synthesis and characterization of new naphthalene-based PFCB aryl ether polymeric isomers with 1,5-, 1,6-, 2,6-, and 2,7-linkages were described. Monomers of perfluorocyclobutane (PFCB) poly(aryl ether)s, 1,5-, 1,6-, 2,6-, and 2,7-bis(trifluorovinyloxy)naphthalene, were synthesized from dihydroxynaphthalenes in two steps and polymerized by 2π + 2π step-growth cyclopolymerization. The naphthalene-based PFCB polymers (PFNs) had a relatively high Tg in the range 106−144 °C and excellent thermal stability at temperatures up to 400 °C. Among PFN polymeric isomers, Tg of the 1,5-linked PFCB polymer (1,5-PFN) was 30−40 °C higher than those of the other naphthalene isomers due to its high steric hindrance around the backbone. The refractive index and birefringence of the PFN polymers in the form of spin-coated films were determined. The PFN isomeric polymers showed tunability in refractive index and the birefringence of the order of 1,5 < 1,6 < 2,6 < 2,7-PFN and 1,5 < 1,6 < 2,7 < 2,6-PFN, respectively. PFN isomers had low birefringences below 0.002 except 2,6-PFN. The lowest value in birefringence was 0.0008 of 1,5-PFN due to its highly kinked structure. Plastic optical fibers of homopolymers, 1,5- and 2,7-PFN, and copolymers, 2,7-co-1,5-PFN and 2,7-PFN-co-6F−PF, were prepared, and optical losses and windows of them were observed. The attenuation loss of PFN polymers was about 0.17−0.27 dB/cm at the wavelength of near-IR optical sources. 1,5-PFN had a lower optical loss than 2,7-PFN. The optical loss of the 2,7-co-1,5-PFN copolymer was effectively reduced compared with that of 2,7-PFN. The lowest optical loss polymer for PFCB POF was 2,7-PFN-co-6F-PF of 0.07 dB/cm at the wavelength of the optical loss window and 0.17 dB/cm at 1300 nm.

Highly Conductive Poly(phenylene thienylene)s: m-Phenylene Linkages Are Not Always Bad

Two isomeric polymers, which contain meta- or para-phenylene linkages between conducting segments, have been synthesized and compared by electrochemical methods. The nonconjugated poly(1,5-diacetoxy-m-phenylene tetrathienylene) (PMPT-OAc) showed similar electroactivity to the para-isomer, poly(2,5-diacetoxy-p-phenylene tetrathienylene) (PPPT-OAc), in the cyclic voltammetry and in-situ conductivity measurements. Spectroelectrochemistry showed a similar buildup of sub-band-gap electronic transitions. Deacetylation of the polymers was performed successfully by reaction with hydrazine, producing PMPT-OH and PPPT-OH. Both phenol-substituted polymers exhibited greater electroactivity than the acetoxy-substituted polymers. In addition, the phenol substituents were found to lower the “turn-on” potential in the conductivity−potential profile for PMPT-OH, but not for PPPT-OH. An alkoxy-substituted PMPT-OMe shows electroactivity similar to that of PMPT-OAc in the cyclic voltammetry, in-situ conductivity, and spectroelectrochemistry.

Flexible Ligands and Structural Diversity: Isomerism in Cd(NO3)2 Coordination Polymers

The ligands 1,4-bis(2-pyridylmethylsulfanylmethyl)benzene (L1) and 2,5-bis(2-pyridylmethylsulfanylmethyl)pyrazine (L2) were treated with Cd(NO3)2.4H2O in metal-to-ligand ratios of 1:1 and 2:1, respectively; L2 was also treated with CdCl2.2.5H2O in a 2:1 ratio. All products were found to be coordination polymers. The crystal structures of {[Cd(L1)(NO3)2].CH2Cl2}infinity (1a), {[Cd(L1)(NO3)2].4/3CH3CN}infinity (1b), {[Cd2(L2)(NO3)4].2CH3CN}infinity (2.2CH3CN), and {[Cd2(L2)Cl4].2CH2Cl2}infinity (3.2CH2Cl2) were determined. Compounds 1a and 1b were found to be conformational supramolecular isomers. The structure of 1b displayed topological isomerism with two isomeric polymer chains, 1b(1) and 1b(2), in the one crystal forming a single supramolecular array. The structure of 2.2CH(3)CN showed Cd2(L2) units linked together by nitrates bridging between the Cd(II) centers in a mode previously not seen in Cd(II) compounds. The overall structure of 3.2CH2Cl2 was found to be similar to that of 2.2CH3CN despite the presence of different anions and solvent molecules. Powder X-ray diffraction was used to investigate the nature of bulk preparations of compounds 1-3.

Syntheses and Properties of Soluble Biphenyl-Based Polyimides from Asymmetric Bis(chlorophthalimide)s

A novel synthesis of asymmetric bis(chlorophthalimide)s (3,4-BCPIs) has been established. The polymerizations of them produced higher molecular weight (0.38−0.51 dL/g) polyimides containing biphenyl units than those of isomeric polymers derived from symmetric bis(chlorophthalimide)s (4,4‘-BCPIs) and 3,3‘-BCPIs. The distribution of the formed biphenyl units of head to tail, head to head, and tail to tail in the chain of the polymers was about 58.0:21.0:21.0, determined by 13C NMR spectra of the polymers. The composition of model compounds, determined by HPLC, was well consistent with the 13C NMR spectrum result. Comparing with polymers derived from 4,4‘-BCPIs and 3,3‘-BCPIs, the polymers derived from 3,4-BCPIs showed better solubilities in N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and N-methylpyrrolinone (NMP). Flexible films could be cast from the polymer solution with the inherent viscosities of above 0.35 dL/g. The polymer derived from asymmetric bis(chlorophthimide)s gave the highest Tg among the isomeric polymers. The 10% weight loss of these polyimides was above 549 °C.

New poly(amide imide imide)s based on tetraimide dicarboxylic acid condensed from 4,4?-(hexafluoroisopropylidene)diphthalic anhydride,m-aminobenzoic acid, and 4,4?-oxydianiline and various aromatic diamines

A series of new, organosoluble, and light-colored poly(amide imide imide)s were synthesized from tetraimide dicarboxylic acid (I) and various aromatic diamines by direct polycondensation with triphenyl phosphite and pyridine as condensing agents. I was prepared by the azeotropic condensation of 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, m-aminobenzoic acid, and 4,4′-oxydianiline at a 2/2/1 molar ratio in N-methyl-2-pyrrolidone (NMP)/toluene. The thin films cast from N,N-dimethylacetamide (DMAc) had cutoff wavelengths shorter than 400 nm (365–394 nm) and color coordinate b* values between 13.10 and 36.07; these polymers were lighter in color than the analogous poly(amide imide)s and isomeric polymers. All of the polymers were readily soluble in a variety of organic solvents, including NMP, DMAc, N,N-dimethylformamide, dimethyl sulfoxide, and even less polar dioxane and tetrahydrofuran. The cast films exhibited tensile strengths of 90–104 MPa, elongations at break of 7–22%, and initial moduli of 1.9–2.4 GPa. The glass-transition temperatures of the polymers were recorded at 274–319°C. They had 10% weight losses at temperatures beyond 520°C and left more than a 50% residue even at 800°C in nitrogen. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 669–679, 2003

Excess viscosity and glass transition

Literature data on the viscosity of solutions of poly(butyl methacrylate) (PBMA) and poly(methyl methacrylate) (PMMA) in diethyl phthalate (DEP) for different temperatures, including the range around and below Tg, the glass transition temperatures of the pure polymers, were evaluated by means of an approach that uses surface fractions as composition variables. The discussion of these results together with information on solutions of the isomeric polymers, poly(vinyl acetate) (PVAc) and poly(methyl acrylate) (PM(A)), in the same solvent testifies that the previously published relations remain valid for T<Tg. They enable the determination of viscosities of the pure polymers below Tg by extrapolating the solution data to vanishing solvent content. The temperature dependencies of the data obtained in this manner demonstrate that the viscosity of PBMA rises upon cooling as expected according to the WLF equation, whereas the increase is lower by several orders of magnitude for PMMA and PVAc. These observations and the temperature dependencies of the system-specific parameters of the present approach are discussed in detail.

Synthesis and properties of alternating copolyamide‐imides based on 2,6‐bis(4‐aminophenoxy)naphthalene and comparison with its related isomeric polymers

AbstractA series of novel polyamide‐imides III containing 2,6‐bis(phenoxy)naphthalene units were synthesized by 2,6‐bis(4‐aminophenoxy)naphthalene and various bis(trimellitimide)s in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents through direct polycondensation. The polymers were obtained in quantitative yield with inherent viscosities up to 1.53 dL/g. Most of the polymers showed good solubility in NMP, N,N‐dimethylacetamide, N,N‐dimethylformamide, and dimethyl sulfoxide and could be solution‐cast into transparent, flexible, and tough films. The films had tensile strengths of 84–111 MPa, elongations at break of 8–33%, and initial moduli of 2.2–2.8 GPa. Wide‐angle X‐ray diffraction revealed that most polymers III were amorphous. The glass‐transition temperatures of some of the polymers could be determined by differential scanning calorimetry traces, recorded at 247–290 °C. The polyamide‐imides exhibited excellent thermal stabilities and had 10% weight loss at temperatures in the range of 501–575 °C under nitrogen atmosphere. They left more than 57% residue even at 800 °C in nitrogen. A comparative study of some corresponding polyamide‐imides is also presented. © 2001 John Wiley &amp; Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2591–2601, 2001

Coordination polymers and isomerism; a study using silver(i) and a π-stacked ligand

The ligand 2,5-bis(2-pyridylmethylsulfanylmethyl)pyrazine (L) was prepared by the base coupling of 2-(sulfanylmethyl)pyridine and 2,5-bis(chloromethyl)pyrazine. This new ligand was treated with AgClO4 in a 1 ∶ 1 metal-to-ligand ratio and with AgNO3 in a 2 ∶ 1 metal-to-ligand ratio to give coordination polymers. The crystal structures of {[Ag(L)]ClO4}∞ (1) and {[Ag2(L)](NO3)2}∞ (2) were determined. The Ag(I) ions in the one-dimensional polymeric chains of 1 adopted square-pyramidal geometries with the pyridine and pyrazine N donors coordinated in an extremely bent fashion. The structure of 2 revealed two isomeric polymer chains in the one crystal forming a single supramolecular array. The isomeric polymers differed in the donor atoms about the Ag(I) ions and in the arrangement of adjacent ligands along the chain. A feature of both structures was that L adopted a three-layer π-stacked arrangement.

New crystalline polymers: poly(2,5-dialkyl-1,4-phenylene oxide)s

New heat-reversibly crystalline poly-(alkylated phenylene oxide)s are described. the oxidative polymerization of 2,5-dimethylphenol catalyzed by (1,4,7-triisopropyl-1,4,7-triazacyclononane) copper dichloride produced poly(2,5-dimethyl-1,4-phenylene oxide), which showed heat-reversible crystallinity with a high melting point at ca. 300°C, although the isomeric polymer, poly(2,6-dimethyl-1,4-phenylene oxide), never recrystallizes once melted. The polymerization of 2,5-diethylphenol and 2,5-dipropylphenol gave the polymers consisting of 1,4-phenylene oxide units; the latter polymer possessed heat-reversible crystallinity, however, the former one did not.

Prediction and Experimental Verification on Blend Phase Diagrams of Two Structurally Isomeric Polymers: Poly(4-methylstyrene) and Poly(α-methylstyrene)

Prediction and Experimental Verification on Blend Phase Diagrams of Two Structurally Isomeric Polymers: Poly(4-methylstyrene) and Poly(α-methylstyrene)

Amino-Functionalized Poly(arylene ether ketone)s

Amino-functionalized poly(arylene ether ketone)s have been synthesized by nucleophilic aromatic substitution from isomeric amino-functionalized monomers and Bisphenol A. The polymerizations have been found to proceed without any side reactions. The polymers were characterized by IR, 1H NMR, and 13C NMR spectroscopy and gel permeation chromatography. The glass transition temperatures and thermal stabilities of the isomeric polymers have been determined by differential scanning calorimetry and thermogravimetry. A strong dependence of the glass transition temperature on the position of the amino function in the polymer backbone was observed. This could be explained by inter- or intramolecular hydrogen bonding. Owing to the good reactivity of the amine groups, those polymers will then allow further modifications and easily lead, for example, to amide formation or to the grafting of various molecules.

Regular σ–π Organosilane Copolymers with Alternating Oligomeric Dimethylsilylene and Cis or Trans Stilbene Units

A series of perfectly alternating copolymers containing oligomeric dimethylsilylene and cis or trans stilbene units has been prepared by the condensation polymerization of silyl ditriflates with the corresponding stilbene dianion. As expected, the spectral characteristics and the polymer processability were very different for the isomeric polymers. Evidence of σ–π interaction was obtained from absorption measurements and the excited state of the Si4 catenates was characteristic of a polar charge transfer state. The polymers are all photoactive and irradiation in the long-wavelength absorption band leads to cis–trans isomerization followed by complete disappearance of the long-wavelength (λ>300 nm) absorption. The latter was not observed for the monomeric model compounds.