Unexpected Absorbance Enhancement upon Clustering Dyes in a Polymer Matrix

Abstract

PE films grafted with poly(methyl acrylate) and labeled with pyrene groups were obtained by irradiation with γ-rays in the presence of acryloyl chloride and further reacting them with 1-pyrenebutanol or 1-pyrenemethylamine. Characterization of the polymer films benefited from the dual use of the pyrene probe as an indicator of, first, polymer chain dynamics by monitoring pyrene excimer formation by fluorescence and, second, polymer morphology by staining the pyrene-rich domains of the films with RuO(4) for scanning electron microscopy (SEM). The grafted polymers labeled with 1-pyrenemethylamine showed much stronger absorbance than those labeled with 1-pyrenebutanol despite having similar pyrene contents. The fluorescence spectra of the grafted polymers labeled with 1-pyrenebutanol exhibited monomer emission, whereas those labeled with 1-pyrenemethylamine exhibited exclusively excimer emission. These dramatic differences could be accounted for by noting that labeling of the grafted poly(acryloyl chloride) with 1-pyrenemethylamine results in cross-linking of the polymer matrix, with an associated enhancement of the concentration of pyrene in the cross-linked domains, which was confirmed by SEM. Formation of discrete domains in the polymer film can induce multiple scattering at the domain boundaries which lengthens the path of light in the film and increases absorption of the light by the tightly packed pyrene-rich domains. Implementation of this effect for fabrication of plastic color filters should generate more efficient filters which should find numerous practical applications.

PEGDA‐based luminescent polymers prepared by frontal polymerization

“…These polymers are blue emitters and exhibit mainly “monomer emission,” which can be due to the fact that the cross‐linked structure of the polymer matrix restrains the mobility of the pyrene units thereby preventing their interaction to form excimers. Very intense excimer emission bands have been observed in other labeled polymers previously reported by us …”

“…The synthesis of 1‐pyrenebutyl acrylate (PyBuAc) has been previously reported by us in the literature . In this case, PyBuOH (2.000 g, 7.289 mmol) was dissolved in freshly distilled THF (50 mL) under argon atmosphere; then TEA (1.500 mL, 10.600 mmol) was added with a syringe to the solution.…”

Photoluminescent Grafted Polymers: Synthesis and Properties of a Polyethylene Matrix Covalently Linked with Porphyrin Units

“…It is possible to get a higher degree of functionalization by doing swelling tests, thereby allowing the monomer AC to penetrate into the polymer matrix before the irradiation. In a previous work, carried out with grafted polymers containing pyrene, we demonstrated by RuO 4 staining that the functionalization of the PE films is very heterogeneous and takes place mainly on the surface …”

Coumarin Grafted Polyethylene Matrix as Colorimetric and Fluorescent Chemosensor for Metal Ions

“…As previously reported in our group, the functionalization of the PE films occurred mainly on the surface and did not modify the mechanical properties and transparency of the films. [ 33–36 ]…”

“…As previously reported in our group, the functionalization of the PE films occurred mainly on the surface and did not modify the mechanical properties and transparency of the films. [33][34][35][36] In order to ensure that the coumarin derivative was successfully grafted onto the PE films, IR, UV, and fluorescence measurements were performed. The FT-IR spectra of the grafted PE films were compared with the FT-IR spectrum of the PE film before grafting (Figure 1).…”