Diffusion of a Single Component in a Binary Polymer Blend upon Annealing Monitored by Fluorescence Microspectroscopy

Abstract

We describe the employment of steady-state fluorescence spectroscopy coupled to epifluorescence microscopy (fluorescence microspectroscopy) for monitoring the diffusion of the lower-T g component during heating of a binary blend of poly(n-butyl methacrylate-co-styrene) containing 9-vinylanthracene units attached as fluorescent label (nBMAS) with polystyrene. The segregation of the nBMAS was monitored by simply measuring the emission spectra over areas of a few micrometers at 40 °C (above nBMAS-T g) near the interfacial region as a function of time, while the morphological changes and the flux of diffusant were readily revealed during the annealing process. The apparent diffusion coefficient, D ap = (1.6 ± 0.1) × 10-6 cm2 s-1, was extracted from the slope of the better linear fitting from the plot of relative intensities (as integrated spectra) vs t 1/2.

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

“…[49][50][51] Methods FTIR spectra of the copolymers were acquired using a Bomem MB-series model B-100 infrared spectrophotometer by casting thin films of the copolymers from chloroform solutions over NaCl windows. All spectra were recorded at room temperature.…”

“…The fluorescence quantum yields, Φ F , of the polymers and copolymers with pyrenyl moieties were determined relative to 9,10-diphenylanthracene (DPA) in ethanol (Φ F = 0.95) according to the relation: 56 (1) where the subscripts s and u indicate the standard (DPA) and unknown sample (copolymers), respectively, A(ν) is the absorbance of the solution at the exciting frequency ν, Φ s is the quantum yield of standard, integrals are the integrated luminescence spectra, and n j are the refractive indices of the pure solvent (for ethanol n s = 1.3611, T = 20 o C) and for the copolymers, n u was estimated using: (2) where n PS is the refractive index of polystyrene Epifluorescence microscopy (EFM) was performed as already described using a Leica DM IRB inverted microscope according the experimental procedure already established. [49][50][51] Steady-state fluorescence spectroscopy was performed using an ISS-PC1 spectrofluorimeter with a photon counting detection system in back-face illumination. The samples were excited at 348 and 460 nm and the fluorescence emissions were collected in the range of 360-690 nm and 480-720 nm.…”

“…[49][50][51] Steady-state fluorescence spectroscopy was performed using an ISS-PC1 spectrofluorimeter with a photon counting detection system in back-face illumination. The samples were excited at 348 and 460 nm and the fluorescence emissions were collected in the range of 360-690 nm and 480-720 nm.…”

“…54,55 Moreover, because the donor and acceptor emissions are of distinct colors (blue and red, respectively), epifluorescence microscopy (EFM) is a very useful tool for both morphological characterization and in situ chemical analysis for identifying every domain of the polymer blend by differences in the color. [48][49][50][51] The morphological studies were further detailed by scanning electron microscopy (SEM). …”

Fotofísica de compostos aromátaicos em microesferas de polímeros biodegradáveis

“…Entretanto diversos trabalhos em blendas poliméricas foram realizados por nosso grupo de pesquisas, um dos pioneiros na aplicação da microscopia de epifluorescência com a finalidade de identificação in situ da composição dos vários domínios em blendas. [132][133][134][135][136][137][138][139][140][141][142][143] No entanto, a microscopia confocal permite que somente uma pequena quantidade desta emissão (tanto do eixo z, paralelo ao eixo óptico do microscópio, O solvente clorofórmio (Tedia, Synth) foi purificado previamente.…”