Facile control of system-bath interactions and the formation of crystalline phases of poly[(9,9-dioctylfluorenyl-2,7-diyl)alt-co-(9,9-di-{5'-pentanyl}-fluoreny1-2,7-diyl)] in silicone-based polymer hosts

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)In this paper poly[(9,9-dioctylfluorenyl-2,7-diyl)-alt-co-(9,9-di-{5'-pentanyl)-fluoreny12,7-diyl)] (PFP) was attached by hydrosilylation reaction to polysiloxanes with lower and higher crosslinking yields. Two types of polysiloxanes were prepared: PDHS-PDVS-l-PFPX and PDHSS-PDVS-h-PFP-X, with increasing amounts of polyfluorene (X = 4.04 x 10-4 mol (1), 4.04 x 10(-5) mol (2) and 4.04 x 10(-6) mol (3)), where land h represent elastomeric and brittle matrices (l = lower crosslinking and h = higher crosslinking yields). Their photophysical properties were studied and compared with the polymer in films, in THF and in two different polysiloxane (poly[(dimethylsiloxane-co-methylvinylsiloxane) dimethylvinylsilyloxyll-terminated-PDVS and poly[(dimethylsiloxane-co-methylhydrogensiloxane) dimethylhydrogensilyloxy] terminated-PDHS) solutions before the hydrosilylation reactions. Based on the steady-state and dynamical photoluminescence data, the polyfluorene chains are, independent of the polyfluorene amount, disordered in solutions, in films and in PDHSPDVS-I-PFP-X. Nevertheless, in both PDHSS solutions and in the PDHSS-PDVS-h-PFP-X hybrid, crystalline phases of the polyfluorene were formed. Moreover, aggregates with green emission are also observed with increasing contents of conjugated polymer. Aggregates emitting in longer wavelengths are only formed when other crystalline phases are present in PDHSS-PDVS-h-PFP-X (X = 2 and 3) silicones. The driving force for this formation is probably a combination of pi-pi interaction between the planar backbone and the hydrophobic interactions of the lateral groups in the poor solvent PDHSS in a more confined environment such as brittle PDHSS-PDVS-h-PFP. (C) 2013 Elsevier Ltd. All rights reserved.493693705Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)UNICAMP/FAEPEXFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Ag/lamellar hosts composites: a route to morphology-controllable synthesis of Ag nanoparticles

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)An easy and novel routine are reported for the preparation of metallic silver nanoparticles (AgNPs) with controlled morphology, using Na+-magadiite swelled with hexadecyltrimethylammonium bromide (CTA(+)-magadiite) and a layered aluminophosphate with kanemite-type structure modified with n-dodecylammonium and n-butylammonium (but, dod-AlPO-kan) as hosts. For the preparation of the metallic AgNPs (Ag-0) in the interlamellar space, the CTA(+)-magadiite and but, dod-AlPO-kan hosts were dispersed in N,N-dimethylformamide (DMF) solution with different AgNO3 concentrations. DMF acts as reducing agent of Ag+ ions leading to nanoparticles with disk-like morphology of magadiite silicate; these were characterized by TEM and UV-Vis spectroscopy. On the other hand, the AgNPs are intercalated in but, dod-AlPO-kanshowing spherical-like morphology. The UV-Vis spectra of the nanocomposites based on Ag-0 and magadiite silicate show bands at 565 nm that can be attributed to Ag-0 nanodisks. The Ag-but, dod-AlPO-kan-based nanocomposites present a band at 422 nm attributed to the surface plasmon resonance of Ag-0 nanospheres. The results of transmission electron microscopy agree very well with XRD and UV-Vis analysis, indicating the formation of AgNPs with different morphologies using the two kinds of lamellar materials. The magadiite host has an important role in the synthesis of Ag nanodisks, because it controls the growth of nanoparticles inside the interlayer region with disk-like morphology due the high interlayer interactions of the silicate, leading to the growth of nanoparticles in only two directions (xy plane). On the other hand, when but, dod-AlPO-kan is used a sphere-like morphology is preferred due the best accommodation of AgNPs between the layers of aluminophosphate host.158Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)European CommunityFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Vanadium oxide intercalated with polyelectrolytes: Novel layered hybrids with anion exchange properties

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Novel anion exchange hybrid materials were developed by the insertion of poly(diallymethylammonium chloride) (PDDACl) and poly(allylamine hydrochloride) (PAHCl) polyelectrolytes into V2O5 interlayer spaces using hydrothermal treatment and were used to host an anionic cyanine dye. A systematic study of the hybrid material synthesis by direct in situ reaction of PDDACl and PAHCl polycations with V2O5 powders showed that the interlayer space of V2O5 expands from 0.44 nm to 1.40 nm and 1.80 nm upon intercalation of PDDACl and PAHCl polyelectrolytes, respectively. X-ray photoelectron spectroscopy and DR UV-Vis-NIR spectroscopy revealed that some V' sites were reduced to V' during the intercalation of the polyelectrolytes, these acted as both charge balancing entities for the negative oxide sheets and carriers for exchange sites located in the V2O5 interlayer space. The interlayer separation is consistent with the existence of coiled conformation of the polycations. The hybrid materials produced [PDDACl](0.24)[PDDA](0.29)V2O5 and [PAHCl](0.28)[PAH](0.47)V2O5, exhibited approximately 45.0% and 37.0% of chloride ions still available for anionic exchange, respectively. These materials were used to encapsulate a cyanine anionic dye. The presence of the dye was evidenced in the [PDDACL](0.24)[PDDA](0.29)V2O5 by significant fluorescence, with emission peak centered at 617 nm. C) 2011 Elsevier Inc. All rights reserved.368462469Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Piedmont Region (Italy) [CIPE 2006]European CommunityConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Piedmont Region (Italy) [CIPE 2006