Effect of dental finishing instruments on the surface roughness of composite resins as elucidated by atomic force microscopy

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Solid-phase peptide synthesis in highly loaded conditions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Coordination polymer adsorbent for matrix solid-phase dispersion extraction of pesticides during analysis of dehydrated Hyptis pectinata medicinal plant by GC/MS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Structural aspects, thermal behavior, and stability of a self-assembled supramolecular polymer derived from flunixin-meglumine supramolecular adducts

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Study of the biodegradation of a polymer derived from castor oil by scanning electron microscopy, thermogravimetry and infrared spectroscopy

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Correlation between solvation of peptide-resins and solvent properties

The solvation properties of model resin and peptide-resins measured in ca. 30 solvent systems correlated better with the sum of solvent electron acceptor (AN) and electron donor (DN) numbers, in 1:1 proportion, than with other solvent polarity parameters. The high sensitivity of the (AN+DN) term to detect differentiated solvation behaviors of peptide-resins, taken as model of heterogeneous and complex solutes, seems to be in agreement with the previously proposed two-parameter model, where the sum of the Lewis acidity and Lewis basicity characters of solvent are proposed for scaling solvent effect. Besides these physicochemical aspects regarding solute-solvent interactions, important implications of this study for the solid phase peptide synthesis were also observed. Each class of peptide-resin displayed a specific salvation profile that was dependent on the amount and the nature of the resin-bound peptide sequence. Plots of resin swelling versus solvent (AN+DN) values allowed the visualization of a maximum salvation region characteristic for each class of resin. This strategy facilitates the selection of solvent systems for optimal solvation conditions of peptide chains in every step of the entire synthesis cycle. Moreover, only the AN and DN concepts allow the understanding of rules for solvation/shrinking of peptide-resins when in homogeneous or in heterogeneous mixed solvents.

Langmuir and langmuir-blodgett films of polyfluorenes and their use in polymer light-emitting diodes

The Langmuir and Langmuir-Blodgett (LB) film properties of two polyfluorene derivatives, namely poly(2,7-9,9'-dihexylfluorene-dyil) (PDHF) and poly(9,9 dihexylfluorene-dyil-vynilene-alt-1,4-phenylene-vyninele) (PDHF-PV), are reported. Surface pressure (Pi-A) and surface potential (Delta V-A) isotherms indicated that PDHF-PV forms true monolayers at the air/water interface, but PDHF does not. LB films could be transferred onto various types of substrate for both PDHF and PDHF-PV. Only the LB films from PDHF-PV could withstand deposition of a layer of evaporated metal to form a light-emitting diode (PLED), which had typical rectifying characteristics and emitted blue light. It is inferred that the ability of the polymer to form true monomolecular layers at the air/water interface seems to be associated with the viability of the LB films in PLEDs.

Manipulation of anchoring strength in an azo-dye side chain polymer by photoisomerization

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)