ADVANCED FUNCTIONAL MATERIALS, Issue 13 2010
Mater.
M. A. Firestone et al. present a polymer that incorporates an electronic component with an ionic liquid and produces a mixed ionic and electronic conductor on page 2063. Electropolymerization of a bifunctional imidazolium-based ionic liquid monomer incorporating both vinyl and thiophene groups yields a liquid-crystalline polymer that adopts an interconnected network structure formed by two orthogonally oriented lamellar sheets. The structural ordering leads to enhanced electrical conductivity. [source]

Electropolymerization of a Bifunctional Ionic Liquid Monomer Yields an Electroactive Liquid-Crystalline Polymer

ADVANCED FUNCTIONAL MATERIALS, Issue 13 2010
Sungwon Lee
Abstract The preparation and polymerization of a bifunctional imidazolium-based ionic liquid (IL) monomer that incorporates both a vinyl group and a thiophene moiety is reported. Potentiodynamic electropolymerization of the monomer produces an optically birefringent polymer film that strongly adheres to the electrode surface. Fourier transform IR spectroscopy shows that polymerization occurs through both the vinyl and thienyl groups. Cylic voltammetry (CV) is used to determine the polymer oxidation potential (1.66,V) and electrochemical bandgap, Eg, of 2.45,eV. The polymer exhibits electrochromism, converting from yellow in the neutral form (,max,=,380,nm) to blue in the polaronic state at 0.6,V (,max,=,672,nm) and to blue-grey in the bipolaronic state at 1.2,V (,max,>,800,nm). Topographic atomic force microscopy (AFM) images reveal isolated (separated) fibrils. Grazing-incidence small-angle X-ray scattering (GISAXS) studies indicate a lamellar structure with a lattice spacing of 3.2,nm. Wide-angle X-ray diffraction (WAXD) studies further suggest that the polymerized thiophene sheets are oriented perpendicular to the polymerized vinylimidazolium. The electrical conductivity, as determined by four-probe dc conductivity measurements was found to be 0.53,S cm,1 in the neutral form and 2.36,S cm,1 in the iodine-doped state, values higher than typically observed for polyalkylthiophenes. The structural ordering is believed to contribute to the observed enhancement of the electrical conductivity. [source]

Grayscale Photopatterning of an Amorphous Polymer Thin Film Prepared by Photopolymerization of a Bisanthracene-Functionalized Liquid-Crystalline Monomer

ADVANCED FUNCTIONAL MATERIALS, Issue 10 2010
Hideyuki Kihara
Abstract A method for grayscale photopatterning of an amorphous polymer film derived from a bisanthracene-functionalized liquid-crystalline monomer is developed. Solution photopolymerization of a monomer with two anthracene moieties, one at each end, affords an amorphous polymer. A combination of irradiation with patterned UV light and heating results in photopatterning on thin films prepared from the polymer. On non-irradiated areas of the film, the polymer reverts to the monomer owing to the thermal back-reaction of the anthracene photodimer, forming an ordered phase. On irradiated areas remaining in the amorphous phase, the thermal back-reaction is suppressed. This phenomenon results in a clear contrast and visual images on the film under polarized light. Grayscale photopatterning is also made possible for the solution-polymerized polymer by controlling the intensity of exposure. In addition, rewritable photopatterning can be achieved by melt photopolymerization of the monomer. The new photopatterning is essentially nondestructive because it needs neither image development nor anthracene-excitation light for reading. [source]

Polymerization of substituted acetylenes by various rhodium catalysts: Comparison of catalyst activity and effect of additives

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 19 2005
Atsushi Nakazato
Abstract This research deals with comparison of the activity of various Rh catalysts in the polymerization of monosubstituted acetylenes and the effect of various amines used in conjunction with [Rh(nbd)Cl]2 in the polymerization of phenylacetylene. A zwitterionic Rh complex, Rh+(nbd)[(,6 -C6H5)B,(C6H5)3] (3), was able to polymerize phenylacetylene (5a), t -butylacetylene (5b), N -propargylhexanamide (5c) and n -hexyl propiolate (5d), and displayed higher activity than the other catalysts examined, that is [Rh(nbd)Cl]2 (1), [Rh(cod)(O - o -cresol)]2 (2), and Rh-vinyl complex (4). Monomers 5a and 5c polymerized virtually quantitatively or in fair yields with all these catalysts, while monomer 5b was polymerizable only with catalyts 3 and 4. Monomer 5d did not polymerize in high yields with these Rh complexes. The catalytic activity tended to decrease in the order of 3 > 4 > 2 > 1. Although polymerization of 5a did not proceed at all in toluene with [Rh(nbd)Cl]2 alone, it smoothly polymerized in the presence of various amines as cocatalysts. The polymerization rate as well as the molecular weight of polymer depended on the basicity and steric bulkiness of amines. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4530,4536, 2005 [source]

Synthesis and Characterization of N -Propargyl Cinnamamide Polymers and Copolymers

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3 2007
Jianping Deng
Abstract This paper deals with synthesis and characterization of a novel poly(N -propargylamide) containing cinnamamide groups (poly(1)) in its side chains. Monomer 1, CHCCH2NHCOCHCH(C6H5), was synthesized and polymerized with a rhodium catalyst, (nbd)Rh+B,(C6H5)4 (nbd,=,2,5-norbornadiene). Effects of some factors on polymerization of monomer 1 such as solvent, temperature, and the ratio of monomer/catalyst were investigated in detail; polymers with moderate number-average molecular weights () and low index of polydispersity () were obtained. To improve the polymers' solubility and to elucidate whether poly(1) could form helical conformation, another N -propargylamide monomer 2, CHCCH2NHCOCH(CH2CH3)2, was employed to accomplish copolymerization with monomer 1. Copolymerization with monomer 2 improved obviously the solubility of the (co)polymers; the copolymers with certain monomer ratios could form helices under the examined conditions according to the related UV-vis spectra. [source]

Atom Transfer Radical Polymerization of Glycidyl Methacrylate: A Functional Monomer

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 16 2004
Pedro Francisco Cañamero
Abstract Summary: A detailed investigation of the polymerization of glycidyl methacrylate (GMA), an epoxy-functional monomer, by atom transfer radical polymerization (ATRP) was performed. Homopolymers were prepared at relatively low temperatures using ethyl 2-bromoisobutyrate (EBrIB) as the initiator and copper halide (CuX) with N,N,N,,N,,N,-pentamethyldiethylenetriamine (PMDETA) as the catalyst system. The high polymerization rate in the bulk did not permit polymerization control. However, homopolymerization in solution enabled us to explore the effects of different experimental parameters, such as temperature, solvent (toluene vs. diphenyl ether) and initiator concentration, on the controllability of the ATRP process. SEC analysis of the homopolymers synthesized confirmed the importance of solvent character on molecular weight control, the lowest polydispersity indices () and the highest efficiencies being found when the polymerizations were performed in diphenyl ether in combination with a mixed halide technique. A novel poly(glycidyl methacrylate)- block -poly(butyl acrylate) (PGMA- b -PBA) diblock copolymer was prepared through ATRP using PGMA-Cl as a macro-initiator. This chain growth experiment demonstrated a good living character under the conditions employed, while simultaneously indicating a facile synthetic route for this type of functional block copolymer. In addition, the isotacticity parameter for the PGMAs obtained was estimated using 1H NMR analysis which gave a value of ,GMA,=,0.26 in agreement with that estimated in conventional radical polymerization. SEC chromatograms of PGMA-Cl macroinitiator and PGMA- b -PBA diblock copolymer. [source]

Luminescent Monomer and Poly(methacrylate) Containing 1,3,4-Oxadiazole and Stilbene Units: Synthesis and Optical Properties

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 14 2004
John A. Mikroyannidis
Abstract Summary: A monomer M as well as a poly(methacrylate) P carrying the same chromophore, that consists of 1,3,4-oxadiazole and stilbene units, were efficiently synthesized. They dissolved in common organic solvents such as THF, chloroform, dichloromethane, 1,1,2,2-tetrachloroethane and chlorobenzene. P showed a Tg value of 145,°C. Both M and P were stable up to approximately 300,°C and afforded anaerobic char yield of about 40% at 800,°C. Their optical properties were comparable. They emitted intense violet-blue light in THF solution with a PL maximum at 413 nm and a PL quantum yield of 0.29 for M and 0.73 for P. Thin films of them displayed optical band gap of 3.03 eV and blue-light emission with a PL maximum around 440 nm. The PL curves of both samples were progressively red-shifted with increasing the solvent polarity. The influence of the annealing on the PL emission spectrum of M and P thin films was investigated. [source]

Use of Hydroxyl Functionalized (Meth)acrylic Cross-Linked Polymer Microparticles as Chain Transfer Agent in Cationic Photopolymerization of Cycloaliphatic Epoxy Monomer, 1

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2003
Ludovic Valette
Abstract In the case of cationic-type photopolymerized epoxy networks, a new type of chain transfer agent based on hydroxyl functional acrylic cross-linked polymer microparticles (CPM, also called microgels) has been tested. The CPM functionality was obtained through hydroxyethyl acrylate (HEA) monomer, used as comonomer with butyl acrylate (BA) and hexane diol diacrylate (HDDA). Stabilizing monomers were also required for the synthesis of CPM. In order to compare their particular effects, 4 sets of CPM were synthesized with 4 different stabilizing agents, either hydroxyl functional or not. Consequently, two types of OH groups were present in the particles: primary groups coming from HEA and preferentially located in the particles, and optional hydroxyl groups due to the hydroxyl functional stabilizing agents which were mainly placed onto the particles' surface. The viscoelastic properties of the photopolymerized films have been used to obtain information about the chain transfer reaction and the network microstructure. In all cases, the rubber modulus, was improved because of the decrease of the number of dangling epoxy chains in the epoxy network. When hydroxyl groups were only present in the particles, the mobility of the linkages was assumed to be low, and the mechanical relaxation temperature, T,, strongly increased. However, CPM aggregation occurred at high CPM concentrations, lowering and T,. On the contrary, when OH groups were located both on the surface as well as inside the particles, no large CPM aggregation took place, even with [CPM],=,40 wt.-%. Nevertheless, the presumably higher mobility of the linkages on the particles' surface prevented any T, increase. The water absorption of all systems based on CPM was very low, around 2% whatever the concentration of chain transfer agent. Schematic description of the transfer reaction between a propagating cationic-type epoxy chain and a hydroxyl functional CPM. [source]

Direct Observation of , -Chloro- p -quinodimethane as the Real Monomer in the Gilch Polymerization Leading to Poly(p -phenylene vinylene)s

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2007
Jens Wiesecke
Abstract It is the general consensus that in Gilch polymerizations the 1,4-bis(chloromethylene)benzene starting material first changes into p -quinodimethane intermediates which then act as the real monomers. However, direct observation of these intermediates has not been possible so far. This is because usually the p -quinodimethane auto-initiates its rapid radical polymerization instantaneously, keeping its concentration extremely low throughout the whole process. Here it is shown that, when the reaction is carried out at very low temperatures, the formation of p -quinodimethane still proceeds but chain growth is suppressed. Hence, the concentration of the active monomer reaches a level sufficient for NMR analysis. [source]

Addition-Fragmentation Chain Transfer to Polymer in the Free Radical Ring-Opening Polymerization of an Eight-membered Cyclic Allylic Sulfide Monomer

MACROMOLECULAR THEORY AND SIMULATIONS, Issue 2 2005
Marisa Phelan
Abstract Summary: A detailed investigation of chain transfer to polymer during free radical ring-opening polymerization of the eight-membered disulfide monomer 2-methyl-7-methylene-1,5-dithiacyclooctane (MDTO) is presented. It has been shown that extensive chain transfer to polymer occurs involving both poly(MDTO) radicals and cyanoisopropyl radicals. Significant decreases in molecular weight were observed when cyanoisopropyl radicals were generated in the presence of poly(MDTO) in the absence of monomer. The molecular weight distribution (MWD) obtained from polymerization of MDTO in the presence of pre-added poly(MDTO) was markedly different from that obtained without pre-added polymer. A kinetic model was constructed in an attempt to quantitatively describe the chain transfer to polymer process based on the addition fragmentation chain transfer mechanism. It was found however that the simulated MWDs were considerably broader than the experimental MWDs, which were similar to the Schulz-Flory distribution. Mechanism for chain transfer to polymer. [source]

Synthesis and characterization of a novel soluble reactive ladder-like polysilsesquioxane with side-chain 2-(4-chloromethyl phenyl) ethyl groups

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2001
Chunqing Liu
Abstract A new kind of soluble structure-ordered ladder-like polysilsesquioxane with reactive side-chain 2-(4-chloromethyl phenyl) ethyl groups (L) was first synthesized by stepwise coupling polymerization. The monomer, 2-(4-chloromethyl phenyl) ethyltrichlorosilane (M), was synthesized successfully by hydrosilylation reaction with dicyclopentadienylplatinum(II) chloride (Cp2PtCl2) catalyst. Monomer and polymer structures were characterized by FT-IR, 1H -NMR, 13C -NMR, 29Si -NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), vapor pressure osmometry (VPO) and X-ray diffraction (XRD). This novel reactive ladder-like polymer has promise potential applications as initiator for atom transfer radical polymerization, and as precursor for a variety of advanced functional polymers. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Vapor species over cerium and samarium trichlorides, enthalpies of formation of (LnCl3)n molecules and Cl,(LnCl3)n ions

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2001
A. M. Pogrebnoi
A Knudsen effusion cell mass spectrometric technique was used to study vapor species over CeCl3 and SmCl3. Monomer, dimer, and trimer (Sm3Cl9) molecules, and LnCl4,, Ln2Cl7,, Ln3Cl10, (Ln,=,Ce, Sm) negative ions, were observed in saturated vapor in the temperature range 958,1227,K. Partial vapor pressures of neutral constituents were determined and the enthalpies of sublimation (,sH, 298,K, kJ·mol,1) to monomers and associated molecules obtained: 328,±,6 (CeCl3), 306,±,6 (SmCl3), 453,±,16 (Ce2Cl6), 408,±,12 (Sm2Cl6), and 468,±,40 (Sm3Cl9). Equilibrium constants for various chemical reactions were measured and the enthalpies of reactions obtained using the second and third laws of thermodynamics. The enthalpies of formation (,fH, 298,K, kJ·mol,1) of molecules and ions have been calculated as follows: ,730,±,6 (CeCl3), ,722,±,6 (SmCl3), ,1663,±,16 (Ce2Cl6), ,1649,±,13 (Sm2Cl6), ,2617,±,40 (Sm3Cl9), ,1250,±,15 (CeCl4,), ,1252,±,15 (SmCl4,), ,2184,±,35 (Ce2Cl7,), ,2172,±,26 (Sm2Cl7,), ,3183,±,43 (Ce3Cl10,), and ,3147,±,43 (Sm3Cl10,). Copyright © 2001 John Wiley & Sons, Ltd. [source]

Synthesis of Well-Defined Hyperbranched Polyamides by Condensation Polymerization of AB2 Monomer through Changed Substituent Effects,

ANGEWANDTE CHEMIE, Issue 32 2009
Yoshihiro Ohta
Der Wechsel des Substituenteneffekts beim Übergang vom Monomer zum Polymer kann genutzt werden, um die selektive Kondensationspolymerisation eines AB2 -Monomers an einem Kernmolekül zu steuern (siehe Schema). Man erhält hochverzweigte Polyamide mit sehr niedriger Polydispersität und einem über das Monomer/Kern-Verhältnis kontrollierbaren Molekulargewicht. [source]

ChemInform Abstract: Coordination of a Uranium(IV) Sulfate Monomer in an Aqueous Solution and in the Solid State.

CHEMINFORM, Issue 20 2008
Christoph Hennig
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

The Heteropolytungstate Core {BW13O46}11, Derived as Monomer, Dimer, and Trimer

CHEMISTRY - A EUROPEAN JOURNAL, Issue 25 2007
Nathalie Leclerc-Laronze Dr.
Abstract A study of the borotungstate system has led to the characterization of new, original compounds based on the unconventional Keggin derivative [H3BW13O46]8, ion (denoted as 1). [H3BW14O48]6, (2) and the dimer [H6B2W26O90]12, (3) crystallize as mixed cesium/ammonium salts and have been characterized by single-crystal X-ray diffraction analysis. Anion 2 reveals an unusual arrangement, consisting of an outer {W3O9} core grafted onto the monovacant [BW11O39]9, Keggin moiety and exhibits an unprecedented distorted square-pyramidal arrangement for a cis -{WO2} core. Elemental analysis, supported by bond distance analysis, is consistent with the presence of three protons distributed over the terminal oxygens of the outer {W3O7} capping fragment. The [H6B2W26O90]12, ion (3) is formally derived from the direct condensation of two [H3BW13O46]8, subunits. The cisoid arrangement of the two [BW11O39]9, subunits, coupled with the antiparallel arrangement of the two quasi-linear OW,,,OWOH2 chains within the central {W4O12} connecting group, breaks any symmetry, thereby resulting in a chiral compound. Polarography and pH-metric titrations reveal the formation of the monomeric precursor [H3BW13O46]8, (anion 1) under stoichiometric conditions. 183W NMR analysis of 2 and 3 in solution gives complex spectra, consistent with the presence of equilibria between several species. In the frame of this study, we also report on a structural re-investigation of the [H6B3W39O132]15, ion (4) based on reliable results obtained in the solid state by means of single-crystal X-ray diffraction analysis, and in solution by means of 1D and 2D COSY 183W NMR. X-ray diffraction analysis revealed the presence of three attached aquo ligands on the central {W6O15} connecting core, generating three OW,,,OWOH2 quasi-linear chains, which are responsible for the chirality of the trimeric assembly. This structural arrangement accounts for the 39-line 183W solution spectrum. The 2D COSY spectrum permits reliable assignments of the six strongly shielded resonances (around ,250 and ,400,ppm) to the six central W atoms, as well as additional assignments. The origin of such strong shielding for these particular W atoms is discussed on the basis of previously published results. Infrared data for compounds 1, 3, and 4 are also presented. [source]

Catalytic Polymerizations of Hydrophobic, Substituted, Acetylene Monomers in an Aqueous Medium by Using a Monomer/Hydroxypropyl- , -cyclodextrin Inclusion Complex

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 2 2009
Lei Ding
Abstract Ten hydrophobic, substituted, acetylene monomers were examined as to their abilities to form an inclusion complex with hydroxypropyl- , -cyclodextrin (HPCD). Only the monomers with suitable substitutents were found to form the monomer/HPCD complex, which was identified by NMR, FTIR, and UV-vis spectroscopy. Polymerizations of the monomers were successfully carried out in aqueous solution by using the prepared monomer/HPCD inclusion complex and by using a water-soluble Rh-based catalyst, [Rh(cod)2BF4] or [Rh(nbd)(H2O)OTs]. Such polymerizations provided high-yield (>90%) polymers with a cis content of approximately 100%. The as-prepared polymers could take an ordered helical conformation, just like their counterparts obtained in organic solvents. [source]

Activation of gelatinolytic/collagenolytic activity in dentin by self-etching adhesives

EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 2 2006
Yoshihiro Nishitani
Mild acids are known to activate dentin matrix metalloproteinase (MMPs). All self-etching dental adhesives are acidic (pH 1.5,2.7) and may activate dentin MMPs. The purpose of this study was to compare the ability of several all-in-one adhesives to activate gelatinolytic and collagenolytic activities in powdered mineralized dentin. Powdered dentin made from human teeth was mixed with all-in-one adhesives (Clearfil Tri-S Bond, G-Bond, Adper Prompt L-Pop) or a self-etching primer (Clearfil SE Bond primer) for varying times and then the reaction was stopped by extracting the adhesives using acetone. Fresh untreated mineralized dentin powder had a gelatinolytic activity of 3.31 ± 0.39 relative fluorescent units (RFU) per mg dry weight (24 h) that increased, over storage time, to 87.5 RFU mg,1 (24 h) after 6,8 wk. When fresh powder was treated with acidic Tri-S Bond, the gelatinolytic activity increased from 3.24 ± 0.70 RFU mg,1 to >,112.5 RFU mg,1 (24 h) after 20 min and then remained unchanged. Monomers with lower pH values produced less activity. There was a significant, direct correlation between gelatinolytic activity and pH, with Tri-S giving the highest activity. Coating dentin powder with Tri-S resin prevented fluorescent substrates from gaining access to the enzyme, even though it activated the enzyme. In conclusion, self-etch adhesives may activate latent MMP and increase the activity to near-maximum levels and contribute to the degradation of resin,dentin bonds over time. [source]

1,3-Diethynylallenes: Stable Monomers, Length-Defined Oligomers, Asymmetric Synthesis, and Optical Resolution

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 21 2007
Matthijs K. J. ter Wiel
Abstract A series of differently substituted 1,3-diethynylallenes (DEAs) have been synthesized, confirming that the previously introduced construction protocols tolerate a variety of functional groups. The new DEAs bear at least one polar group to facilitate enantiomer separations on chiral stationary phases and to allow further functionalization. They are thermally and environmentally stable compounds since bulky substituents next to the cumulene moiety suppress the tendency to undergo [2+2] cyclodimerization. A series of length-defined oligomers were obtained as mixtures of stereoisomers by oxidative coupling of a monomeric DEA under Glaser,Hay conditions. The electronic absorption data indicate a lack of extended ,-electron conjugation across the oligomeric backbone due to the orthogonality of the allenic ,-systems. Remarkably, even complex mixtures of stereoisomers only yield one single set of NMR signals, which underlines the low stereodifferentiation in acyclic allenoacetylenic structures. Optical resolution of DEAs represents an amazing challenge, and preliminary results on the analytical level are reported. Asymmetric synthesis by Pd-mediated SN2,-type cross-coupling of an alkyne to an optically pure bispropargylic precursor opens another promising route to optically active allenes with stereoselectivities currently reaching up to 78,% ee. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]

Nanostructured Organic,Inorganic Composite Materials by Twin Polymerization of Hybrid Monomers

ADVANCED MATERIALS, Issue 20 2009
Stefan Spange
Abstract Forming two structurally different but associated polymer structures in a single step is a possible route for the production of nanostructured materials. By means of twin polymerization of specially constructed monomers consisting of two different covalently bonded building blocks (hybrid monomers), this route is realized. What is important is that two different macromolecular structures are formed from one monomer in a single process. The two polymers formed can be linear, branched, or cross-linked structures. The molecular composition of the hybrid monomer defines the degree of cross-linking of the corresponding macromolecular structures that is theoretically possible. [source]

Synthesis of well-defined polymeric activated esters

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2008
Patrick Theato
Abstract Monomers bearing an activated ester group can be polymerized under various controlled polymerization techniques, such as ATRP, NMP, RAFT polymerization, or ROMP. Combining the functionalization of polymers via polymeric activated esters with these controlled polymerization techniques generate possibilities to realize highly functionalized polymer architectures. Within this highlight two different research areas of activated esters in polymer science will be discussed: (i) the preparation of defined reactive polymer architectures by controlled polymerization techniques and (ii) the preparation of defined reactive thin films. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6677,6687, 2008 [source]

Effect of molecular architecture and size of mesogen on phase behavior and photoactive properties of photoactive liquid crystalline hyperbranched polyester epoxies containing benzylidene moiety

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 2 2008
V. Srinivasa Rao
Abstract A series of photoactive liquid crystalline linear and hyperbranched polyester epoxies were synthesized by polyaddition of photoactive bis benzylidene alkanone diol monomers and terephthalic acid and trimesic acid respectively with good yield. The effect of molecular architecture (linear and hyperbranched), size of mesogenic unit (cyclic and acyclic units) on the physicochemical, thermal, mesogenic, and photoactive properties of hyperbranched polymers were studied and compared. Degree of branching of hyperbranched polymers was found to be in the range of 0.46,0.49. Monomers containing cyclic moieties only exhibited nematic mesophase, while all polymers exhibited typical nematic mesophase. Intermolecular photo cycloaddition reaction was studied by ultraviolet,visible spectra (UV,vis) and NMR spectroscopy and photo viscosity measurement of UV irradiated polymer solutions. Faster photo induced behavior of hyperbranched polymers containing acyclic alkanone moiety, as compared to polymers containing cycloalkanone moieties, was observed. The change in the refractive index was found to be in the range of 0.02,0.024. Substantial variation of refractive index indicates that this polymer could be used for optical recording. All the polymers were also found to be fluorescent in nature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 552,563, 2008 [source]

Frontal polymerization with monofunctional and difunctional ionic liquid monomers

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2007
Zulma Jiménez
Abstract For the first time, we studied frontal polymerization with ionic liquid monomers. We synthesized a series of compounds from the neutralization reaction between trialkylamines (tributylamine, trihexylamine, trioctylamine, and (2-dimethylamino)ethyl methacrylate) and acrylic or methacrylic acid. For the ionic liquids prepared from the unreactive amines, frontal polymerization could not be achieved without the addition of a diacrylate. With the addition of a diacrylate, the front velocities were slower than for dodecyl acrylate (with the diacrylate), a compound of comparable molecular weight. Monomers prepared from the (2-dimethylamino)ethyl methacrylate could support frontal polymerization alone but the front velocities were lower than dodecyl (meth)acrylate. These results are contrasted with recent results of Jiménez et al. for room temperature kinetics. Finally, the polymers prepared were comparable to those prepared by batch curing at 75 °C except for the monomethacrylate ionic liquid, which lost some tertiary amine by dissociation and evaporation. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2745,2754, 2007 [source]

Polymerization of substituted acetylenes by various rhodium catalysts: Comparison of catalyst activity and effect of additives

Low-oxidation-potential conducting polymers derived from 3,4-ethylenedioxythiophene and dialkoxybenzenes

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 13 2001
Jennifer A. Irvin
Abstract Monomers derived from 3,4-ethylenedioxythiophene and phenylenes with branched or oligomeric ether dialkoxy substituents were prepared with the Negishi coupling technique. Electrooxidative polymerization led to the corresponding dialkoxy-substituted 3,4-ethylenedioxythiophene,phenylene polymers, with extremely low oxidation potentials (E1/2,p = ,0.16 to ,0.50 V vs Ag/Ag+) due to the highly electron-rich nature of these materials. The polymers were electrochromic, reversibly switching from red to blue upon oxidation, with bandgaps at about 2 eV. The electrochemical behavior of the oligomeric ether-substituted polymer was investigated in the presence of different metal ions. Films of the polymer exhibited electrochemical recognition for several alkali and alkaline-earth cations with selectivity in the order Li+ > Ba2+ > Na+ > Mg2+. Cyclic voltammetry showed a decrease in the oxidation potential and an improvement in the definition of the voltammetric response, as well as an increase in the overall electroactivity of the polymer films when the concentration of the cations in the medium was increased. These results are discussed in terms of the electrostatic interactions between the complexed cation and the redox center, as well as the diffusion of the ionic species into the polymer matrix. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 2164,2178, 2001 [source]

Synthesis and Characterization of , -Cyclodextrin Based Functional Monomers and its Copolymers with N -isopropylacrylamide

MACROMOLECULAR BIOSCIENCE, Issue 12 2003
Yu-Yang Liu
Abstract Two novel monovinyl , -cyclodextrin (, -CD) monomers are synthesized. Their chemical compositions are characterized by means of element analysis, NMR and FT-IR spectroscopy. The results show that the synthesis techniques used are convenient and efficient. Using N -isopropylacrylamide as a comonomer, two novel linear copolymers can also be synthesized. Synthesis route of monovinyl , -CD monomers. [source]

New Second-Order Nonlinear Optical Polymers Derived from AB2 and AB Monomers via Sonogashira Coupling Reaction

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 8 2010
Zhong'an Li
Abstract In this paper, a facile route was designed to prepare a new AB2 -type polymer P1 via simple Sonogashira coupling reaction, also its corresponding linear analog (P2) was obtained from AB monomer for comparison. Despite the relatively lower loading density of the effective chromophore moieties, P1 demonstrated higher second-harmonic coefficient (153.9,pm,·,V,1) than that of P2 (98.2,pm,·,V,1), due to the three-dimensional spatial isolation effect of the hyperbranched structure. The good results of P2 also indicated that the ladder shape may help to solve the problem existing in main-chain polymers, the low poling efficiency. [source]

Multifunctional Polymethacrylates Obtained Via ATRP of Functional and Reactive Monomers Followed by Polymer Analogous Reaction with Functional Amines

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19 2008
Dragos Popescu
Abstract Starting from methyl methacrylate (MMA), butyl methacrylate (BMA), allyl methacrylate (AMA), phenoxycarbonyloxy ethyl methacrylate (PCEMA), and functional amines different multifunctional polymethacrylates are accessible. The reactive monomer PCEMA was synthesized starting from 2-hydroxyethyl methacrylate, and then copolymerized via ATRP with other methacrylates in order to obtain reactive copolymers which were subjected to polymer analogous reactions with different functional amines leading to multifunctional polymethacrylates. These can be used for the preparation of multifunctional surfaces. [source]

Main-Chain Liquid Crystalline Polymers Based on Bis-Etherified 9,9-Dihexyl-2,7-bis(4,-hydroxy-1,1,-biphen-4-yl)fluorenes

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 13 2007
Tanja Sovi
Abstract A series of liquid crystalline compounds based on 2,7-bis(biphenyl)fluorenes was synthesised by a Suzuki cross-coupling reaction and subsequent etherification with different bromoalkenes. By simple variations of the chain lengths the temperature range in which the nematic mesophase is present could be tuned. The described approach offers the possibility of covalent incorporation of the mesogens into polymers via olefin metathesis techniques, resulting in enlarged stability of the mesophase. Monomers and polymers could be easily aligned on rubbed polyimide substrates as revealed by polarised absorption spectroscopy. [source]

Copolymerization of Fluorinated Monomers with Hydrophilic Monomers in Aqueous Solution in Presence of Cyclodextrin

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 11 2006
Oliver Kretschmann
Abstract Summary: New fluorinated copolymers were synthesized by copolymerization of 1H,1H,2H,2H- perfluorodecyl methacrylate (1) with hydrophilic comonomers methacrylic acid (3), 2-acrylamido-2-methylpropane sulfonic acid (6), 3-trimethylammonium propyl methacrylamide chloride (7) and N,N -dimethylmethacrylamidopropyl- N -3-sulfopropylammoniumbetaine (8). The reaction was carried out in water using randomly methylated , -cyclodextrin (RAMEB) for solubilization of the fluorinated monomer by forming a host-guest complex (1a). Polymerization kinetics were investigated and copolymerization parameters were determined. Additionally, a RAMEB complex of tert -butyl methacrylate (2a) was copolymerized with 1a in water. For comparison, copolymerization of the uncomplexed monomers 1 and 2 were carried out in organic solvents. Evaluation of copolymerization kinetics and parameters showed significant differences in the relative reactivities of the free monomers and the monomer-RAMEB complexes. [source]

Controlled Radical Polymerization of Vaporized Vinyl Monomers on Solid Surfaces under UV Irradiation

MACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 4 2004
Mikio Yasutake
Abstract Summary: In order to prepare well-defined polymers on solid surfaces in the gas phase, a gas phase-assisted surface polymerization (GASP) of vinyl monomers was carried out on solid surfaces pre-coated with a photoiniferter, 2-cyanoprop-2-yl N,N,-dimethyldithiocarbamate, under UV irradiation. The GASP of methyl methacrylate (MMA) resulted in the formation of polymer on the surfaces and showed a proportional relationship between and polymer yield. Consecutive copolymerization of MMA and styrene led to the formation of a block copolymer, which was confirmed by a selective solvent fractionation method. These results demonstrate that controlled radical polymerization of vaporized monomer occurred on the solid surfaces. Expected mechanism of GASP under UV irradiation. [source]