Untitled

Abstract

E-glass fibers were silanized using a 1% (v/v) aqueous solution of ␥-aminopropyltriethoxysilane (APES). Pyrenesulfonamide conjugates were formed by reaction of 1-pyrenesulfonyl chloride (PSC) in acetonitrile (AcN), with the amine groups immobilized on the glass fiber surface. These pyrene-sulfonamide conjugates were used as fluorescence probes, being a relatively simple analytical method to study the coating microstructure of polyorganosiloxane layer on glass fibers. The first aim of this work was to estimate possible interactions of the polyaminosiloxane coating with surrounding molecules of different solvents (solvent accessibility to the chromophore). For this study, the fluorescence response of pyrene-sulfonamide dye (PSA) was correlated with solvent polarity parameters. It was concluded that all the studied solvents were accessible to the chromophore, and they can gather in two groups, depending on their ability to swell the poliorganosiloxane layer. The second objective was to estimate the rigidity of the coating polymer from the temperature dependence of PSA emission. At about 180 K, a sudden change in the behavior of different photophysical parameters of PSA were observed. This phenomenon was interpreted as a density change in the polyaminosiloxane attached to the glass fibers.

Phase‐separation process in a poly(methyl methacrylate)‐modified epoxy system: A novel approach to understanding the effect of the curing temperature on the final morphology

“…The fluorescence emission from many molecules or groups (fluorophores) is so sensitive to changes in their immediate surroundings that very small amounts of them are enough to obtain much information. In general, the fluorescence emission changes when polarity and/or rigidity variations occur in the system where the fluorophore is immersed 31–40. For example, there has been an important amount of work done with fluorescence to follow polymerization processes 24, 25, 36, 41–52.…”

Effect of Glass Fiber Surface Treatments on Mechanical Strength of Epoxy Based Composite Materials

“…Recent studies have focused on the characterization of glass f ber coatings (18,21). Some f uorescent molecules, such as dansyl derivatives, show appreciable shifting in their f uorescence emission band depending on the polarity and/or rigidity of their surroundings (22,23).…”

Single-Step Dispersion of Functionalities on a Silica Surface

“…As a matter of fact, the three main bands at 380, 400, and 420 nm are centered at the same wavelengths as those of the parent molecule N -(phenyl)-1-pyrenesulfonamide in toluene solution. Furthermore, molecules bearing a similar pyrene sulfonamide chromophore displayed emission bands close to these maxima. – Using the terminology of Thomas et al also taken up by González-Benito et al, the bands at 380 and 400 nm are referred to as band I and band V, respectively. In the silica materials, bands I and V were used as an index of the polarity by analogy with the well-known polarity py-scale in solutions .…”

“…Furthermore, molecules bearing a similar pyrene sulfonamide chromophore displayed emission bands close to these maxima. [65][66][67] Using the terminology of Thomas et al 68 also taken up by Gonza ´lez-Benito et al, 65 the bands at 380 and 400 nm are referred to as band I and band V, respectively. In the silica materials, bands I and V were used as an index of the polarity 65 by analogy with the well-known polarity py-scale in solutions.…”

“…[65][66][67] Using the terminology of Thomas et al 68 also taken up by Gonza ´lez-Benito et al, 65 the bands at 380 and 400 nm are referred to as band I and band V, respectively. In the silica materials, bands I and V were used as an index of the polarity 65 by analogy with the well-known polarity py-scale in solutions. 68 In addition to these structured bands, one observes a broad emission above 435 nm arising from pyrene excimers.…”