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Precursor Polymer (precursor + polymer)
Selected AbstractsConjugated Polymers: High-Resolution Scanning Near-Field Optical Lithography of Conjugated Polymers (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Mater. The fabrication of high-resolution nanostructures in both poly(p -phenylene vinylene), PPV, and a crosslinkable derivative of poly(9,9,-dioctylfluorene), F8, using scanning near-field optical lithography, is reported. The ability to draw complex, reproducible structures with 65000 pixels and lateral resolution below 60 nm (< ,/5) is demonstrated over areas up to 20 ,m × 20 ,m. Patterning on length-scales of this order is desirable for realizing applications both in organic nanoelectronics and nanophotonics. The technique is based on the site-selective insolubilization of a precursor polymer under exposure to the confined optical field present at the tip of an apertured near-field optical fiber probe. In the case of PPV, a leaving-group reaction is utilized to achieve insolubilization, whereas the polyfluorene is insolubilized using a photoacid initiator to create a crosslinked network in situ. For PPV, resolubilization of the features is observed at high exposure energies. This is not seen for the crosslinked F8 derivative, r-F8Ox, allowing us to pattern structures up to 200 nm in height. [source] High-Resolution Scanning Near-Field Optical Lithography of Conjugated PolymersADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Daniel Credgington The fabrication of high-resolution nanostructures in both poly(p -phenylene vinylene), PPV, and a crosslinkable derivative of poly(9,9,-dioctylfluorene), F8, using scanning near-field optical lithography, is reported. The ability to draw complex, reproducible structures with 65000 pixels and lateral resolution below 60 nm (< ,/5) is demonstrated over areas up to 20 ,m × 20 ,m. Patterning on length-scales of this order is desirable for realizing applications both in organic nanoelectronics and nanophotonics. The technique is based on the site-selective insolubilization of a precursor polymer under exposure to the confined optical field present at the tip of an apertured near-field optical fiber probe. In the case of PPV, a leaving-group reaction is utilized to achieve insolubilization, whereas the polyfluorene is insolubilized using a photoacid initiator to create a crosslinked network in situ. For PPV, resolubilization of the features is observed at high exposure energies. This is not seen for the crosslinked F8 derivative, r-F8Ox, allowing us to pattern structures up to 200 nm in height. [source] Chemical and electrochemical synthesis of conducting graft copolymer of acrylonitrile with anilinePOLYMER INTERNATIONAL, Issue 9 2006S Hossein Hosseini Abstract A new conducting copolymer, polyacrylonitrile- graft -polyaniline (PAN- g -PANi), has been prepared by chemical and electrochemical methods from a precursor polymer. Poly[acrylonitrile- co -(acrylimine phenylenediamine)] (PAN- co -PAIPD) was synthesized chemically by reacting PAN with sodium 1,4-phenylenediamine salt. PAN- g -PANi was synthesized chemically using ammonium peroxydisulfate as the oxidant and p -toluenesulfonic acid in dimethylsulfoxide solution and adding aniline to oxidized PAN- co -PAIPD. Electrochemical polymerization was carried out by spin coating PAN- co -PAIPD on the surface of a Pt electrode, then the growth of the graft copolymer (PAN- g -PANi) in the presence of fresh aniline and acidic solution. The structures of the graft copolymer and PAN- co -PAIPD were characterized using UV-visible, Fourier transform infrared, and 1H and 13C NMR spectroscopies. The thermal properties of PAN- g -PANi were studied using thermogravimetric analysis and differential scanning calorimetry. Scanning electron microscopy (SEM) images showed that the morphology of PAN- g -PANi copolymer films was homogeneous. Electrical conductivity of the copolymer was studied using the four-probe method, which gave a conductivity of 4.5 × 10,3 S cm,1 with 51.4% PANi. SEM and electrical conductivity measurements supported the formation of the graft copolymer. Copyright © 2006 Society of Chemical Industry [source] Viscoelastic properties of polyacrylonitrile terpolymers during thermo-oxidative stabilization (cyclization)POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2008K. I. Suresh Abstract A study on the thermo-oxidative stabilization (cyclization) of polyacrylonitrile (PAN) terpolymers using dynamic mechanical thermal analysis (DMTA) is reported in this article. When the changes in viscoelastic properties were monitored in a rectangular tension mode, besides the tan , peak characteristic of the glass transition observed below 200°C, the copolymer and the terpolymer displayed a second peak above 200°C due to the cyclization leading to the formation of ladder structures. The initiation temperature of the cyclization process as well as the peak temperature is found to depend on the acid value and the composition of the precursor polymer. The results presented show that monitoring the changes in viscoelastic properties during cyclization provides insight into the material properties as a result of the chemical changes that are taking place. These observations were confirmed by structural characterization using IR spectroscopy, and the observed chemical changes agree with the literature studies, as due to the thermal cyclization process. Copyright © 2008 John Wiley & Sons, Ltd. [source] Hybrid Polymerization of Vinyl and Hetero-Ring Groups of Glycidyl Methacrylate Resulting in Thermoresponsive Hyperbranched Polymers Displaying a Wide Range of Lower Critical Solution TemperaturesCHEMISTRY - A EUROPEAN JOURNAL, Issue 31 2009Zhifeng Jia Dr. Abstract Hybrid polymerization of glycidyl methacrylate (GMA) with potassium hydride (KH) and various oligo(ethylene glycol)s as the initiating system, in which both vinyl polymerization and ring-opening polymerization occur simultaneously, generates hyperbranched poly(ether-ester)s. The reaction process has been followed by an in situ nuclear magnetic resonance technique. The experimental results indicate that both the vinyl and epoxy groups of GMA undergo polymerization, with the reactivity of the latter being much higher than that of the former. Interestingly, the resulting hyperbranched polymers exhibit a sharp phase transition in water at the lower critical solution temperature (LCST). Significantly, the LCST values can be accurately controlled from 0 to 100,°C by changing the hydrophilic/hydrophobic balance of GMA and various oligo(ethylene glycol)s or by modification of the precursor polymer through acetylation. This novel stimuli-responsive hyperbranched polymer is a promising candidate for a new generation of commercially viable thermoresponsive polymers following on from the widely used poly(N- isopropylacrylamide) (PNIPAM). [source] Synthesis of polymeric 1-iminopyridinium ylides as photoreactive polymersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2010Daniel Klinger Abstract Two synthetic routes to polymeric 1-imino pyridinium ylides as new photoreactive polymeric architectures were investigated. In the first approach, polymerization of newly synthesized 1-imino pyridinium ylide containing monomers yielding their polymeric analogues was achieved by free radical polymerization. Alternatively, reactive precursor polymers were synthesized and converted into the respective 1-imino pyridinium ylide polymers by polymer analogous reactions on reactive precursor polymers. Quantitative conversion of the reactive groups was achieved with pentafluorophenyl ester containing polymers and newly synthesized photoreactive amines as well as by the reaction of poly(4-vinylbenzoyl azide) with a photoreactive alcohol. The polymers obtained by both routes were examined regarding their photoreaction products and kinetics in solution as well as in thin polymer films. Contact angle measurements of water on the polymer films before and after irradiation showed dramatic changes in the hydrophilicity of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 832,844, 2010 [source] Facile synthesis of functional polyperoxides by radical alternating copolymerization of 1,3-dienes with oxygenTHE CHEMICAL RECORD, Issue 5 2009Eriko Sato Abstract We have developed a facile synthesis of degradable polyperoxides by the radical alternating copolymerization of 1,3-diene monomers with molecular oxygen at an atmospheric pressure. In this review, the synthesis, the degradation behavior, and the applications of functional polyperoxides are summarized. The alkyl sorbates as the conjugated 1,3-dienes gave a regiospecific alternating copolymer by exclusive 5,4-addition during polymerization and the resulting polyperoxides decomposed by the homolysis of a peroxy linkage followed by successive , -scissions. The preference of 5,4-addition was well rationalized by theoretical calculations. The degradation of the polyperoxides occurred with various stimuli, such as heating, UV irradiation, a redox reaction with amines, and an enzyme reaction. The various functional polyperoxides were synthesized by following two methods, one is the direct copolymerization of functional 1,3-dienes, and the other is the functionalization of the precursor polyperoxides. Water soluble polyperoxides were also prepared, and the LCST behavior and the application to a drug carrier in the drug delivery system were investigated. In order to design various types of degradable polymers and gels we developed a method for the introduction of dienyl groups into the precursor polymers. The resulting dienyl-functionalized polymers were used for the degradable gels. The degradable branched copolymers showed a microphase-separated structure, which changed owing to the degradation of the polyperoxide segments. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 000,000; 2009: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.200900009 [source] | |||||||||||||