Preparation of polymers with pendant quinonoid groups and their photocrosslinking with visible light irradiation

Photosensitive polymers with pendant quinonoid groups were prepared by the reaction of p-(benzoquinon-2-ylthio) acetic acid (QTAA) or p-(p-benzoquinon-2-ylthio)benzoic acid (QTBA) with hydroxyethyl methacrylate-methyl methacrylate copolymer. The polymers showed a strong π-π^* absorption band at around 410 nm and were efficiently crosslinked by visible light irradiation. Somewhat higher photosensitivity of QTAA-bound polymer compared with that of QTBA-bound polymer suggested some contribution of intramolecular hydrogen abstraction of QTAA to the photocrosslinking.     

Novel luminescent polymers containing backbone triphenylamine groups and pendant quinoxaline groups

Novel, conjugated polyfluorene derivatives that comprised an electron-donating triphenylamine group in the backbone and pendant, electron-accepting quinoxaline moieties, were synthesized via the Suzuki coupling reaction and their UV–vis absorption, fluorescence emission and electrochemical properties were investigated. The copolymers were readily soluble in common organic solvents and displayed good film-forming ability and excellent thermal stability. Electroluminescence devices, comprising indium tin oxide/poly(3,4-ethylenedioxythiophene) doped with poly(styrenesulfonic acid)/emitting polymer/Ba/Al, in which the polymers were employed as emissive layers, exhibited superior performance compared to that of corresponding, poly(9,9-dioctylfluorene) and poly(9,9-dioctylfluorene-co-4,4′-triphenylamine) based devices, indicating that the polymers offer promise as emissive materials in polymeric light-emitting diodes.     

Synthesis and thermal stability,dielectric, and conductivity characteristics of polymers with pendant and backbone anthracene sulfonyl groups

Anthracene-mono- and disulfonyl derivatives of polystyrene and poly (N-vinylcarbazole) have been prepared and the thermal stability, dielectric, and conductivity of these polymer pendant sulfones have been evaluated. The anthracene-based benzene, naphthalene, anthracene, and biphenyl copolysulfones have also been prepared and characterized in regard to the above-cited properties. Interesting variations in these properties between these two classes of polymers carrying pendant and backbone sulfonyl groups have been noted and rationalised from structural considerations.     

Synthesis and characterization of coordination polymers of polyesters with pendant amino groups

Oligomeric polyester, namely, poly(tetramethylene aspartate) (PTMA), was synthesized from D ,L -aspartic acid and 1,4-butanediol by a melt-condensation technique. Polyester–metal complexes were synthesized by the reaction of PTMA with hydrated acetates of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Mg(II), Ca(II), Pb(II), and Ce(IV) in DMSO. The polyester–metal complexes were characterized by elemental analysis, IR spectral studies, magnetic susceptibility measurements, and thermogravimetry. The metal ions were found to be six-coordinated with two water molecules as additional ligands besides oxygen and nitrogen atoms of polyester repeating units. Thermogravimetric analysis (TGA) showed that coordination polymers are thermally more stable than is polyester. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 751–759, 1998     

Preparation of polystyrene resin with pendant vicinal dioxime groups

Preparation of macroporous polystyrene beads having pendant vicinal dioxime groups and their metal chelating ability is described. Acetylated polystyrene resin crosslinked with 2 mol-% divinyl benzene was oxidized with SeO₂ to give the polymer bearing glyoxyloyl side groups. Then, treating with hydroxylamine, the polymer possessing dioxime groups was obtained. Metal absorbtivity and decomplexation of the resulting polymeric resin were investigated in a wide pH range.     

Metal catalyzed photocrosslinking of polymers containing pendant propargyl groups

Polymers containing the pendant propargyl groups can be effectively crosslinked upon UV irradiation in the presence of a small amount of W(CO)₆. The alkyne-tungsten carbonyl complex was formed initially as evident by IR spectroscopy, which was involved in the subsequent crosslinking reaction. Analyses by UV, IR, and ¹³C NMR CP/MAS spectroscopic methods confirmed the polymer crosslinking as a result of the conversion of the acetylenic units to the polyene and diacetylene moieties in the crosslinked system.     

Soluble polystyrenes with pyrrole pendant groups and their electroactive properties

Summary Four soluble styrenic polymers containing 3-substituted pendant pyrrole rings with ester or amide arm spacer were synthesized. Their electroactive characteristics were investigated by cyclic voltammetry. The chemical oxidation was accomplished by adding FeCl₃ into a solution of styrenic polymers dissolved in 1:1 mixture of dimethylformamide (DMF) and acetonitrile (ACN). The electrical conductivities of the chemically oxidized black powder of the styrenic polymers were in the range of 10^-1010^-9 S/cm.     

A new thermal analytical technique for acrylic polymers

Summary An unconventional thermal analytical technique has been developed for acrylic polymers. By adding water to the polymer the melting point is depressed well below the onset temperature of cyclic thermal degradation. This addition of water depresses the melting point of polyacrylonitrile from 320°C to 185°C. The melting behavior of acrylic copolymers in the wet and dry state is explained in terms of the Eby model of a polymer crystal whereby the non-crystallizable comonomers enter the crystal lattice as defects. The melting point and heat of fusion are interpreted as a measure of the regularity and strength of the intermolecular dipolar bonding that stabilizes the lattice.     

Synthesis, light emission, and photo-cross-linking of luminescent polyacetylenes containing acrylic pendant groups

New poly(1-phenyl-1-alkyne)s bearing acrylic pendants (-{(C₆H₅)CC[(CH₂)_mOCOCHCH₂]}_n-; P1(m), m=3, 9) with high molecular weights are synthesized in high yields by WCl₆-Ph₄Sn catalyst. The structures and properties of P1(m) are characterized and evaluated by IR, NMR, TGA, UV, and PL analyses. All the polymers are solution-processable and thermally stable (T_d≥380 °C). Upon photoexcitation, the polymers emit strong blue lights with emission efficiencies (>40%) comparable to that of poly(1-phenyl-1-octyne), an emissive disubstituted polyacetylene. No excimeric absorption and emission are observed in the thin films of the polymers. The acrylic moieties of P1(m) are readily cross-linked by UV irradiation without harming their optical properties, which may enable them to find high-tech applications in photoresist, luminescent patterning, and light-emitting diodes.     

Novel polyacetylenes containing pendant 1-pyrenyl groups: synthesis, characterization, and thermal and optical properties

We report the synthesis as well as the thermal, optical and photophysical properties of four different polyacetylenes with pendant 1-pyrenyl groups: poly(1-ethynylpyrene) (PEP), poly(1-(trimethylsilanylethynyl)pyrene) (PTMSEP), poly(1-(4-(trimethylsilanyl-buta-1,3-diynyl)pyrene) (PTMSBDP) and poly(1-buta-1,3-diynylpyrene) (PBDP). Polymerizations were carried out with W and Ta catalysts, respectively, for mono- and disubstituted monomers. Soluble poly(1-ethynylpyrene) with high molecular weights (up to 4×10⁵) and extended conjugation of the main chain was obtained with good yields. Lower molecular weights (up to 6×10³) were obtained with the other polymers. Oligomers and polymers displayed high thermal stability. From the absorption spectra of the various polymers, it is found that PEP possesses a higher degree of conjugation than the other polyacetylenes. Molecular interactions occur between pyrene units present in each polymer giving rise to an emission due to associated pyrenes. These interactions are affected by the steric hindrance present in the polymer backbone. Excitation spectra combined with fluorescence decay profiles show that these interactions occur in the ground state (excited complex).     

Synthesis and properties of polynorbornenes bearing oligomeric siloxane pendant groups

The ring-opening metathesis polymerization (ROMP) of norbornene derivatives 1-5 bearing oligomeric siloxane pendant groups was carried out with Grubbs 1st and 2nd generation, and Grubbs-Hoveyda ruthenium (Ru) catalysts. Monomer 1 gave high-molecular-weight polymers (M_n ca. 27?000-180?000) in high yields (80-100%). Monomers 2-5 also polymerized with Ru carbene catalysts to give high-molecular-weight polymers (M_n ca. 34?000-240?000) in high yields (66-100%). The onset temperatures of weight loss (T₀) of the polymers were 180-250 °C. The glass transition temperatures (T_gs) of poly(1) and poly(2) bearing branched siloxane linkages were near or higher than room temperature (27 and 101 °C). Meanwhile, the T_gs of poly(3)-poly(5) bearing linear siloxane linkages were much lower (−115 to −23 °C), and decreased with increasing length of the siloxane linkages. Poly(1) and poly(2) were hydrogenated completely, which was confirmed by ¹H NMR spectroscopy. The free-standing membranes of poly(1) and poly(2) showed high gas permeability; especially poly(2) is the most permeable to various gases among ROMP-polynorbornene derivatives reported so far.     

Synthesis, characterization, and properties of a novel acrylic terpolymer with pendant perfluoropolyether segments

A novel acrylic terpolymer with pendant perfluoropolyether (PFPE) segments has been synthesized and fully characterized. By hexamethylene diisocyanate functional groups PFPE monofunctional macromonomers have been grafted on a poly(butyl methacrylate-co-hydroxyethyl acrylate-co-ethyl acrylate) random terpolymer. Such grafted copolymer behaves like an interface-active material, since the perfluoropolyether segments in solvent cast films rearrange themselves at the air-polymer interface by surface segregation. In addition, blends of the above graft copolymer with acrylic base polymers (either the terpolymer itself or a commercial copolymer) have been examined in terms of surface segregation and fluorine enrichment of the external layers.The critical surface tension, γ_c, of solid films made of the neat graft copolymer as well as of the polymer blend has been evaluated by contact angle measurements and Zisman plots. Even a small addition (5 wt%) of the fluorinated copolymer to the acrylic component has been found very effective in lowering the surface tension. The outermost surface composition has been investigated by XPS technique, confirming the strong fluorine enrichment. Furthermore, SEM and EDX analyses have been performed on cross-sectioned films, showing that in the above polymer blends macrophase surface segregation has originated a thick layer made of fluorinated copolymer close to the air-polymer interface.     

Synthesis and properties of poly(phenylacetylene)s with pendant imino groups

Summary Polymerization of phenylacetylenes containing imino groups with a variety of transition metal catalysts was investigated. The monomers employed were N-(4-ethynylbenzylidene)aniline (1), N-(3-ethynylbenzylidene)aniline (2), N-(4-ethynylbenzylidene)-2,6-diisopropylaniline (3), N-(4-ethynylbenzylidene)-4-hexylaniline (4), N-(4-ethynylbenzylidene)butylamine (5), and N-(4-ethynylbenzylidene)octylamine (6). All of the monomers smoothly polymerized with [(nbd)RhCl]₂-Et₃N to give polymers in excellent yields, whereas no polymerization took place with W, Mo, and Fe catalysts. The produced polymers were orange to red solids and soluble in common organic solvents except for poly(1). UV-vis spectra of the polymers indicated that the main chains possess a similar degree of conjugation to that of poly(phenylacetylene). However, the stability of polymer backbone toward oxidative cleavage in solution remarkably improved, which is contributed by the electron-withdrawing character of imino groups. Received: 24 August 1999/Accepted: 29 September 1999     

Dynamic mechanical properties of polypentenamers with pendant ionic groups and their hydrogenated derivatives

Dynamic mechanical properties of substituted polypentenamers having thioglycolate side groups and their hydrogenated derivatives have been studied. Methyl esters, acids and salts were investigated at two concentrations, 5.5 mole (%) and 9.2 mole (%). In the un-hydrogenated derivatives one principal relaxation, labelled β, exists in the temperature range from-160 to 100°C. This relaxation arises from microbrownian segmental motion accompanying the glass transition. Its temperature is affected by the concentration of substituent but not the chemical nature of the substituent. A ‘rubbery plateau’ region exists in the acid and salt derivatives and in the latter the salt groups act as reinforcing fillers in this plateau region, consistent with the ionic domain model for their structures. In the hydrogenated derivatives, three relaxations occur in the temperature range from ?160 to 120°C and these are labelled α, β, and γ in order of decreasing temperature. The α relaxation arises from motions associated with the crystal phase except in the case of the 9.2 mole (%) sodium salt derivatives where it arises from motions occurring within ionic domains. The β relaxation arises from microbrownian segmental motions accompanying the glass transition, and the γ relaxation arises from localised motions which may involve both amorphous and crystalline phase components.     

Synthesis and properties of a modified unsaturated polyester resin with phosphorus-containing pendant groups

A novel modified-unsaturated polyester resin (M-UPR) with phosphorus-containing pendant groups was successfully prepared by employing a bifunctional acid, 2-[10-(9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide-10-yl)]-maleic acid (DOPO-MA) as monomer. Characterization of DOPO-MA and M-UPR was performed using element analysis, ¹H-NMR, or FT-IR. The curing of M-UPR was measured by differential scanning calorimetry, and the optimal cure temperature was calculated with DSC curves at different heating rates. The thermal stability was investigated with thermogravimetric analysis and comparative FT-IR analysis for char residue before and after heating. The flame-retardant property was determined by limiting oxygen index measurements and UL94 flammability meter. The viscoelastic property was measured with dynamic mechanical analysis. Owing to the incorporation of the rigid structure of pendant phosphorus groups, both thermal stability and flame retardancy of the resultant M-UPR have been improved.     

Steric and electronic effects on mesophase stability of segmented liquid crystalline polymers with arylazomethine pendant groups

Summary The kinetics of DL-lactide polymerization was studied in CH₂Cl₂ at 25°C and in toluene at 70°C with HAPENAlOMe, a new Schiff's base complex derived from 2-hydroxyacetophenone and ethylenediamine. A higher polymerization rate is observed with this initiator as compared to other previously reported Al-alkoxides complexes. The polymerization with HAPENAlOMe is also shown to be a living process in both solvents. Moreover, the polymerization proceeds to quite high conversion without significant occurrence of transesterification reactions as confirmed from ¹³C NMR and SEC analysis. Received: 4 October 1999/Accepted: 6 December 1999     

RAFT synthesis of acrylic polymers containing diol or dioxane groups

In this paper, the morphology of thermotropic systems with fixed domains (TSFD) was evaluated applying high resolution Atomic Force Microscopy (AFM) also upon heating and cooling. Furthermore nano-mechanical characteristics of the samples were determined by means of Force/Distance spectrometry. TSFD formulated with additive types exhibiting a short chain length displayed roughly spherical scattering particles with dimensions between 0.6???m and 4???m. By means of Force Distance spectroscopy stiffness values of 0.6?N/m and 7.8?N/m were determined for the scattering domains and the matrix, respectively. Upon heating, melting and deliquescence of the additive along with migration was ascertained. After cooling to ambient temperature the formation and growth of terrace-like additive domains on the surface was recorded. Additive types with long-chain molecules developed anisotropic scattering domains resembling distorted disks without predominating orientation. Diameters up to 50???m and a thickness between 200?nm and 600?nm were ascertained. Determination of stiffness yielded values of 0.9?N/m and 13.1?N/m of the scattering domains and the matrix, respectively. Upon heating, swelling and deliquescence of the additive were detected. After cooling to ambient temperature a partial recovery of swelling was observed. Force-Distance spectroscopy yielded a 5 to 10?nm thick additive layer which coated wide areas of the surface after the heating cycle for all samples investigated.     

Polyphenylquinoxalines containing pendant phenylethynyl groups: Preliminary mechanical properties

Polyphenylquinoxalines (PPQ's) containing various amounts of crosslinkable pendant phenylethynyl groups were prepared from the reaction of 3,3′,4,4′-tetraaminodiphenyl ether, 4,4′-oxydibenzil, and 4,4′-oxybis(4″-phenylethynylbenzil). The distribution of the pendant phenylethynyl groups along the polymer chain was varied in an attempt to alter the properties of the polymers. Preliminary film, adhesive, and laminate properties of PPQ void of pendant crosslinkable groups and containing pendant phenylethynyl groups were determined. The thermally induced reaction of the phenylethynyl group crosslinked the polymer which resulted in better dimensional stability at elevated temperatures.     

Novel ionenes with allyl pendant groups

Summary Novel ionenes with allyl pendant groups have been synthesized by condensation of N,N'- bisallylpiperazine with organic dihalides such as 1,4-dichlorobutane, 1,6-dibromohexane and 1,4-dichloromethylbenzene. The polymers are readily soluble in water and have low molecular weights. The structure of the ionenes has been identified by spectroscopic techniques. The concentrated aqueous solutions of the resulting ionenes can be crosslinked by t-butylhydroperoxide as a radical initiator to give transparent hydrogels. The ionenes also act as an crosslinking agent in copolymerization with high concentrations of acrylic acid in the presence of K₂S₂O₈ as a radical initiator in water at 65°C. Received: 29 July 1999/Revised version: 28 October 1999/Accepted: 28 October 1999     

Sulfonated polynaphthalimides with benzimidazole pendant groups

A series of new polyimides bearing simultaneously sulfonic acid groups and benzimidazole rings in different proportions have been synthesised by one pot high temperature polycondensation. The composition of the copolymers, as well as the distribution of the ionic sites along the polymer chain, has been changed systematically in order to study their relation with polymer properties. The incorporation of sulfonic side groups in the structure improves the solubility in polar organic solvents. In turn, the presence of sulfonic acid moieties impairs thermal resistance. Membranes based on the synthesised polyimides were prepared by solution casting and their water uptake as well as proton conductivity were determined.