Photophysical Study in Blends of Poly(alkyl methacrylate-co-styrene)/Polystyrene

Abstract

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). Time-resolved 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. Some miscibility was observed for the blends of XMAS/PS containing 5, 20, and 95 wt % of copolymer. Interaction strength in blends increased with the size of aliphatic chain of the ester group in the copolymer. Blends with 50 wt % of copolymer are always immiscible. Two values of glass transition temperatures were observed by DSC and DMTA. MMAS/PS and EMAS/PS blends of copolymer-richer compositions (95 and 80 wt %) show fluorescence lifetimes with broader distributions, suggesting a wider distance distribution of interlumophoric groups.

Polyfluorene based blends for white light emission

“…Therefore, taking this set of individual polymers, the absorption bands range from 325 to 550 nm, and the photoluminescence bands in solution that appears in the 400-600 nm range, cover almost the entire visible region. structure in the range of 300-420 nm, characteristic of the anthracenyl moieties, with the 0-0 band centered at k abs(0-0) = 390.2 nm [22,34,35]. This spectrum is broader and redshifted by 2.5 nm compared to the dilute solution.…”

“…2 presents the absorption and emission spectra of each polymer separately, recorded from the respective chloroform solutions (10 À5 mol L À1 ). Absorption of the P(MMA-co-MMAnt) is composed by a well defined vibronic structure in the range from 300 to 398 nm, characteristic of the anthracenyl moieties with the 0-0 band centered at k abs(0-0) = 387.8 nm, and emission with the 0-0 band centered at k em(0-0) = 393 nm [22,34,35]. Considering the 0-0 band for both absorption and emission, the Stokes shift is 341 cm À1 .…”

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.…”

“…[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). …”