Publication:
Host/Guest Simulation of Fluorescent Probes Adsorbed into Low-Density Polyethylene, 1. Excimer Formation of 1,3-Di(1-pyrenyl)propane

Loading...
Thumbnail Image
Identifiers
Publication date
2001-11
Defense date
Advisors
Tutors
Journal Title
Journal ISSN
Volume Title
Publisher
John Wiley & Sons, Inc.
Impact
Google Scholar
Export
Research Projects
Organizational Units
Journal Issue
Abstract
Molecular dynamics and Rotational Isomer State/Monte Carlo techniques with a Dreiding 1.01 Force Field are employed to study the excimer formation of isolated 1,3-di(1-pyrenyl)propane and the probe adsorbed into a low-density polyethylene (LDPE) matrix model. The probability of formation of each molecular conformer at several temperatures was calculated using these theoretical techniques. Conformational statistical analysis of the four torsion angles (ϕ₁, ϕ₂, θ₁, θ₂) of Py3MPy showed that the angles —C—Cᵃʳ— (ϕ₁, ϕ₂) present two states c ± = ±90°; and the angles —C—C— (θ₁, θ₂), the three trans states = 180°, g ± = ±60°. The correlation of θ₁–θ₂ torsion angles showed that the most probable pairs were g⁺g⁻ and g⁻g⁺ for the excimer-like specimens, although these angles are distorted because of interactions with the polymer matrix. The temperature dependence of the excimer-formation probability revealed that this process was thermodynamically controlled in the isolated case. When the probe was adsorbed into the LDPE matrix, the excimer formation process was reversed at T = 375 K. At T > 375 K, the behavior was similar to the isolated case but, at T < 375 K, excimer formation probability increased with temperature as found experimentally by steady-state fluorescence spectroscopy. This temperature was coincident with the onset of the LDPE melting process, determined experimentally by thermal analysis.
Description
Keywords
1,3-di(1-pyrenyl)propane, Fluorescence, Monte Carlo simulation, Molecular dynamics, Polyethylene (PE)
Bibliographic citation
Pozuelo, J., Atvars, T. D. Z., Bravo, J. & Baselga, J. (2001). Host/Guest Simulation of Fluorescent Probes Adsorbed into Low-Density Polyethylene, 1. Excimer Formation of 1,3-Di(1-pyrenyl)propane. Macromolecular Theory and Simulations, 10 (9), pp. 808-815.