The Role Of A Catalyst In The Isotopically Excited Laser Photochemistry

Laser photochemistry of BCl3/H2 using catalysis was carried out experimentally. The 10.55 μm radiation from a high power (GW/cm2) TEA CO2 pulse laser was used to selectively excite the 11BCl3 molecules. Using Ti catalyst the reaction products analyzed were 10B11BH2Cl 4, 11B11BH2Cl4, and HCl, whereas those were 10B11BCl4, 11B11BCl4, and HCl when Pb metal powder was employed, i.e., 10B10BH2Cl4 and 10B10BCl4 molecules were not generated in our experiment. Moreover, it was found that the 10BCl3 concentration in the unreacted BCl3 gas increased from 20% to 37% after 360 laser pulses, but the isotopic enrichment was not obtained for the reaction products. The mechanisms for the observed catalytic laser photochemistry are proposed. © 1978 American Institute of Physics.6894233423

Probing Interchain Interactions In Emissive Blends Of Poly[2-methoxy-5- (2′-ethylhexyloxy)-p-phenylenevinylene] With Polystyrene And Poly(styrene-co-2-ethylhexyl Acrylate) By Fluorescence Spectroscopy

We present dynamic and static photoluminescence studies on polymer blends of conjugated poly[2-methoxy-5-(2′-ethylhexyloxy)-p-phenylenevinylene] (MEH-PPV) with polystyrene-co-1-pyrenyl methyl methacrylate and its copolymer poly(styrene-co-2-ethylhexyl acrylate-co-1-pyrenylmethyl methacrylate) (with 9 mol% and 19 mol% of 2-ethylhexyl acrylate units and 0.06 mol% of 1-pyrenyl). Pyrenyl-labeled polystyrene and its copolymers were synthesized by emulsion polymerization and characterized by 13C and 1H-NMR, FTIR, GPC, DSC, and UV-Vis. Spin-coating films of the blends were prepared from chloroform solutions with 0.1, 0.5, 1.0, and 5.0 wt% of MEH-PPV. The miscibility of these systems was studied by non-radiative energy transfer processes between the 1-pyrenyl moieties (the energy donor) and MEH-PPV (the energy acceptor). 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The Effect Of Dye-polymer Interactions On The Kinetics Of The Isomerization Of 4-dimethyl-aminoazobenzene And Mercury Dithizonate

Thermal and photo-isomerization reactions of mercury dithizonate and 4-dimethyl-aminoazobenzene were studied in solutions and in polymer matrices. We used exponential functions to calculate the rate constants for both processes. The kinetic behavior was well described by monoexponential functions for these dyes dissolved in solvents, although bi-exponential functions are required when these dyes are dissolved in polymers. The rate constants are strongly influenced by dye/solvent and dye/polymer interactions, as well as by the aging processes of the polymer matrix. In general, the reaction is faster in more polar mediums, solvents or polymer matrices, since stabilization of different tautomers takes place. We also showed that larger molecules isomerize slowly and slower isomerization has also been observed for annealed samples. Both results are attributed to the importance of free-volumes in polymeric matrices.152253261Natansohn, A., Rochon, P., (2002) Chem. 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Improving The Electroluminescence Of [zn(salophen)(oh2)] In Polyfuorene-based Light-emitting Diode: The Role Of Energy Transfer And Charge Recombination

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Combining two or more different compounds with advantageous properties has been a useful and straightforward strategy in achieving a new class of materials with improved physical properties. This has been especially true for electronic polymers, whose optoelectronic properties can be completely tuned, and even improved, when mixed with other polymeric materials, dye molecules and guest coordination compounds. Here, a light-emitting diode prepared with the conjugated polymer poly[(9,9-dioctylfuorenyl-2,7-diyl)-alt-co-(9,9-di-{5′-pentany1}-fuoreny12,7-diy1)] (PFOFPen) as the host material and aquo[N,N′-bis(salicylidene)-o-phenylenediamine] zinc(II) ([Zn(salophen)(OH2)]) as the guest molecule was studied in terms of its photo and electroluminescence properties. The role of the ZnII coordination compound as a guest in the electroluminescence is discussed as a strategy for the improvement of the electroluminescence performance of coordination compounds using conjugated polymers as matrices. An additional advantage of these composites is that they are solution processable, a low-cost and time efficient alternative to vacuum vapor deposition. Additionally, the photophysical processes involved in both electroluminescence and photoluminescence emissions are discussed because they are markedly different. © 2016 Sociedade Brasileira de Química.2722953022013/16245-2, FAPESP, Conselho Nacional de Desenvolvimento Científico e Tecnológico470529/2012-1, CNPq, Conselho Nacional de Desenvolvimento Científico e TecnológicoFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Phosphorescence Lifetime In Polymer Relaxation Studies: Phase Resolution Method [aquisição De Tempos De Vida De Fosforescência Com Resolução De Fase E Sua Aplicação Ao Estudo De Relaxações Em Polímeros]

We describe in this work a simple experimental set up to perform time dependent luminescence experiments in time scales from mili-seconds to seconds, based on the phase resolution of the emission signal. This system is composed by modulation of a continuous light source with an external chopper controlled by a lock-in amplifier. We exemplified the utility of the system in studies of phosphorecence emission using benzophenone dissolved in polystyrene and since the phosphorescence intensity and lifetime are temperature-dependent processes, we also studied polymer relaxation processes in the temperature range from 20 to 400K. A software that drives the spectrofluorimeter and controls both the cryosystem and the lock-in amplifier was developed.213332336Birks, J.B., (1970) Photophysics of Aromatic Molecules, , Willey-Interscience, LondonSakurovs, R., Ghiggino, K.P., (1981) Aust. J. Chem., 34, p. 1367Rabek, J.F., (1982) Experimental Methods in Photochemistry and Photophysics, , John Willey & Sons, AvonO'Connor, D., Phillips, D., (1984) Time-Correlated Single Photon Counting, , Academic Press, LondonBailey, E.A., Rollefson, G.K., (1954) J. Chem. Phys., 21, p. 1315McGown, L.B., Bright, F.V., (1984) Anal. Chem., 56, pp. 1400A(1989) Manual de Operação do Amplificador Lock-in SR530, , Stanford Research SystemsTalhavini, M., Atvars, T.D.Z., (1995) Quím. Nova, 18, p. 298Sabadini, E., (1988), Tese de MestradoUNICAMPTalhavini, M., (1995), Dissertação de MestradoUNICAMPGuillet, J.E., (1988) Advances in Photochemistry, 14, p. 91. , Volman, D. H.Hammond, G. S. and Gollnick, K. (editores:), Wiley, New YorkHalary, J.L., Monnerie, L., (1986) Photophysical and Photochemical Tools in Polymer Science, 182, p. 589. , NATO ASI Series, Winnik, M. (editor), D. Riedel, New YorkRusakonics, R., Byer, G.W., Leermakers, P.A., (1971) J. Am. Chem. Soc., 93, p. 3263Hikosaka, Y., Hikida, T., (1996) Chem. Phys., 203, p. 137Zevenhuijzen, D., Van Der Werf, R., (1977) Chem. Phys., 26, p. 27

Whitening Regenerated Cellulose Fibers Using Fluorescent Agent, Surfactants, And Salt-color Indices Measurements

The whitening efficiency of regenerated cellulose fibers using sodium 4,4′-distyrylbiphenyl sulfonate in the presence of an anionic surfactant (sodium dodecylsulfate) and a cationic surfactant (dodecyl trimethyl ammonium chloride) and salt (NaCl) was determined by fluorescence spectroscopy and color index values (brightness, whiteness, and yellowness). Epifluorescence images gave an intense blue color with an apparent uniform emission distribution. In absence of salt, the whitening efficiency was higher for aqueous solutions containing cationic surfactant below critical micellar concentration (cmc). In presence of salt, whitening efficiency was higher for anionic surfactant and more important. The concentration of surfactant required for greater brightness, whiteness, and yellowness was lower than that required in absence of salt. These data were discussed by the decrease of the cmc and by the screening of the modified cellulose fibers by counter ions coming from the salt. The role of surfactants was explained by the admicelization during the sorption process. © 2011 Wiley Periodicals, Inc.124543714380Blackburn, R.S., Harvey, A., Kettle, L.L., Manian, A.P., Payne, J.D., Russell, S.J., (2007) J Phys Chem B, 111, p. 8775Mischnick, P., Heinrich, J., Gohdes, M., Wilke, O., Rogmann, N., (1985) Macromol Chem Phys, 2000, p. 201Jakob, H.F., Fengel, D., Tschegg, S.E., Fratzl, P., (1995) Macromolecules, 28, p. 8782Ha, M.A., Apperley, D.C., Evans, B.W., Huxham, M., Jardine, W.G., Vietor, R.J., Reis, D., Jarvis, M.C., (1998) Plant J, 16, p. 183Muller, M., Hori, R., Itoh, T., Sugiyama, J., (2002) Biomacromolecules, 3, p. 182Abu-Rous, M., Ingolic, E., Schuster, K.C., (2006) Cellulose, 13, p. 411Kreze, T., Strnad, S., Stana-Kleinschek, K., Ribitsch, V., (2001) Mater Res Innov, 4, p. 107Krassig, H., (1978) Tappi, 61, p. 93Kotek, R., (2007) Handbook of Fiber Chemistry, p. 667. , In, 3rd ed. Lewin, M. Ed.CRC Press: New YorkStana-Kleinschek, K., Strnad, S., Ribitsch, V., (1999) Polym Eng Sci, 39, p. 1412Stana, K.K., Pohar, C., Ribitsch, V., (1995) Colloid Polym Sci, 273, p. 1174Timofei, S., Schmidt, W., Kurunczi, L., Simon, Z., (2000) Dyes Pigments, 47, p. 5Sarrazin, P., Beneventi, D., Chaussy, D., Vurth, L., Stephan, O., (2009) Colloids Surf A: Physicochem Eng Aspects, 334, p. 80Iamazaki, E.T., Atvars, T.D.Z., (2007) Langmuir, 23, p. 12886Leaver, I.H., Milligan, B., (1984) Dyes Pigments, 5, p. 109Canonica, S., Kramer, J.B., Reiss, D., Gygax, H., (1997) Environm Sci Tech, 31, p. 1754Choudhury, A.K.R., (2006) Textile Preparation and Dyeing, , Science Publishers: New YorkIamazaki, E.T., Atvars, T.D.Z., (2006) Langmuir, 22, p. 9866Lewis, D.M., (1998) J Soc Dyers Col, 114, p. 264Vigil, M.R., Bravo, J., Baselga, J., Yamaki, S.B., Atvars, T.D.Z., (2003) Curr Org Chem, 7, p. 197Schurr, O., Yamaki, S.B., Wang, C.H., Atvars, T.D.Z., Weiss, R.G., (2003) Macromolecules, 36, p. 3485Baldi, L.D.C., Iamazaki, E.T., Atvars, T.D.Z., (2008) Dyes Pigments, 76, p. 669Iamazaki, E.T., Pereira-Da-Silva, M.A., Carvalho, A.J.F., Romero, R.B., Gonôalves, M.C., Atvars, T.D.Z., (2010) J Appl Polym Sci, p. 118. , electronic version available since junePinto, R., Amaral, A.L., Ferreira, E.C., Mota, M., Vilanova, M., Ruel, K., Gama, M., (2008) BMC Biotechnol, 8, p. 7Berns, R.S., Reiman, D.M., (2002) Col Res Appl, 27, p. 360Billmeyer Jr., F.W., Saltzman, M., (1981) Principles of Color Technology, , 2nd ed. Wiley-Interscience: New YorkSenthilkumar, A., (2007) Dyes Pig, 75, p. 356Imura, K., (2007) Color Res Appl, 32, p. 195Imura, K., (2007) Color Res Appl, 32, p. 449Smit, K.J., Ghiggino, K.P., (1991) J Polym Sci Part B-Polym Phys, 29, p. 1397Aloulou, F., Boufi, S., Belgacem, N., Gandini, A., (2004) Colloid Polym Sci, 283, p. 344Alila, S., Boufi, S., Belgacem, M.N., Beneventi, D., (2005) Langmuir, 21, p. 8106O'Haver, J.H., Harwell, J.H., (1995) Surfactant Adsorption and Surface Solubilization, p. 49. , Sharma, R. Ed.ACS Symposium Series 615, American Chemical Society: Washingto

In Situ Chemical Analysis Of Domains In Polymer Blends By Optical Fluorescence Microscopy

Poly(vinyl alcohol) (PVA)/poly(vinyl acetate) (PVAc) blends in different proportions show phase separation in the solid state. The dimensions, shapes, and distributions of the domains produced by the phase separation process are dependent on the composition and can be observed by conventional optical microscopy. However, using fluorescence optical microscopy of polymer blends in different compositions containing anthracene and/or fluorescein molecules dissolved in the matrices we were able to do a chemical discrimination of each domain. We also observed that anthracene is mainly localized in PVAc domains and fluorescein in PVA domains, and that the diffusion process of these fluorophers within the matrices is controlled by specific polymer-dye interactions.58477978

Photoluminescence Study Of β Relaxation Of Polyethylene Blends

Secondary β relaxation of polyethylene blends (50/50 HDPE/LDPE) were studied by photoluminescence of anthracene molecules dissolved in the polymer bulk. The temperature of the β relaxation has been determined as Tβ = -40°C by the dependence of the ratio of vibronic components of the fluorescence band on the temperature. The molecular mechanism of this relaxation has been discussed considering the possibility of the energy migration involving anthracene molecules in the singlet electronic excited and ground states.5091591159

Manufacture Of Sheets Using Post-consumer Unsaturated Polyester Resin/glass Fibre Composites

The storage of post-consumer unsaturated polyester/glass fibre composites impacts negatively on the environment due to its persistence (long lifetime of both the glass fibre and the resin) as well as the high volume/weight ratio of the residues. In this work we introduce a new approach for the recycling process of artefacts made of these polyester/glass fibre composites that involves the dispersion of the ground, not powdered, composite in raw polyester resin. Room temperature resin curing was employed. Flexural and impact tests were performed to optimize the processing conditions and the manufacturing process. Significant improvement in texture, flexural strength and impact resistance of sheets were achieved by pressing and heating the sheets at 40∞C and 50∞C during curing. The artefacts utilized in our work were post-consumer public telephone weather protector caps, which, in Brazil, are manufactured with a composite of unsaturated polyester/glass fibre. Although we used this specific artefact, the methodology can be extended to different types of post-consumer materials or industrial scraps.182111125Vallete, L., Hsu, C.-P., (1999) Polymer, 40, p. 2059Nielsen, E.L., (1974) Mechanical Properties of Polymers and Composites, 2. , Marcel Dekker, New YorkMartin, J.L., (1999) Polymer, 40, p. 3451Plano de Trabalho - Avaliação do Protetor Plástico para o Telefone Público (1997), (10). , Technical Report, CPqD (Brazil)Kojima, A., Furukawa, S., (1997) Adv. Comp. Mat., 6, p. 215Ehrig, R.J., (1992) Plastics Recycling: Products and Process, , Hanser, New YorkFigueiredo, E.M., (1991) Anais do I Congresso Brasileiro de Polímeros, , São PauloPetterson, J., Nilsson, P., (1994) J. Therm. Comp. Mat., 7, p. 57GM200 APVs and their use of composites (1990) Automotive Engng., 98, p. 51Winter, H., Mostert, H.A.M., Smeetes, P.J.H.M., Paas, G., (1995) J. Appl. Polym. Sci., 57, p. 1409Torres, A., De Marco, I., Caballero, B.M., Laresgoiti, M.F., Legarreta, J.A., Cabrero, M.A., (2000) Fuel, 79, p. 897Risson, P., Carvalho, G.A., Vieira, S.L., Zeni, M., Zattera, A.J., (1998) Polímeros: Ciênci. Tecnol., p. 89. , Jul/SetMarcovich, N.E., Reboredo, M.M., Aranguren, M.I., (1996) J. Appl. Polym. Sci., 61, p. 119Devi, M.S., Murugesan, V., Rengaraj, K., Anand, P., (1998) J. Appl. Polym. Sci., 69, p. 1385Bignozzi, M.C., Saccani, A., Sandrolini, F., (2000) Composites: Part A, 31, p. 97Pedroso, A.G., PhD thesis, Unicamp (Campinas), (Brazil), in progressStandard test methods for flexural properties of unreinforced and reinforced plastics and electrical insulating materials (1995), ASTM D 790-95-aAmerican Society for Testing and Materials, PhiladelphiaC for impact resistance of plastics and electrical insulating materials (1993), ASTM D 256-93aAmerican Society for Testing and Materials, Philadelphi

Photophysical Study In Blends Of Poly(alkyl Methacrylate-co-styrene)/ Polystyrene

The morphology of blends of poly(alkyl methacrylate-co-styrene)/polystyrene [XMAS/PS; X = M (methyl), E (ethyl)] was studied at the microscopic level (micrometric scale) by differential scanning calorimetry (DSC), dynamic-mechanical analysis (DMA), and epifluorescence microscopy (EFM) and at the nanoscopic scale by steady-state and time-resolved fluorescence emission spectroscopy (FES). Timeresolved energy transfer analysis was used to probe the interpenetration of molecular chains. The copolymers MMAS and EMAS (approximate content in mol %: 78% of methacrylate units; 22% of styrene units) covalently labeled with 9-vinylanthracene units (≤0.1%), as fluorescent comonomer (fluorophore), were synthesized by emulsion polymerization and were characterized by FTIR, 1H NMR, 13C NMR, TGA, GPC, DSC, DMA, UV-vis, and FES. Films of copolymer blends were prepared by casting from dilute chloroform solutions with compositions of 5, 20, 50, 80, and 95 wt % of copolymer. 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