Matrix effects on the photochemical fatigue resistance of fulgide-doped polymers

Tork, Amir; Lafond, Christophe; Pouraghajani, O.; Bolte, Michèle; Ritcey, Anna M.; Lessard, Roger A.

doi:10.1117/1.1495494

Cited by 6 publications

References 7 publications

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Photochromic Responses in Polymer Matrices

Ramachandran

Urban

2011

Handbook of Stimuli‐Responsive Materials

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IntroductionMany concepts of photochromic systems have been inspired by nature. An illustrative example is the reversible shape changes of the photoreceptor molecule rhodopsin in eyes that produces a cascade of molecular rearrangements responding to light illumination [1]. Upon photoexcitation, all-trans retinal undergoes isomerization to 11-cis across the double bond, thus causing shape changes. Although this event occurs at the angstrom (Å) level, there are many molecular interconnected events and responses that are not fully understood. Similar processes have been observed in certain molecules in materials chemistry, although on a much smaller and at a less-orchestrated scale. These are known as photochromic molecules, which were discovered over 150 years ago in an organic crystal of tetracene, and later on, in inorganic and organometallic materials [2][3][4]. In spite of a long research history, a quest for new photochromic materials continues. Color changes induced by ultraviolet (UV) radiation caused by trans − − cis isomerization, ring opening-closing reactions, inter-or intramolecular charge transfer, or bimolecular cycloaddition reactions are of particular interest. To make use of their photochromic behavior in various applications, photochromic entities are often incorporated into polymer matrices.While creating individual molecules and understanding their electronic properties facilitated further advances in understanding molecular mechanisms governing photochromism, useful applications require fabrication into films, sheets, fibers, or beads. This is typically achieved by incorporating photochromic molecules into macromolecular matrices by doping or dispersing, or covalently attaching them onto a polymer backbone. Since photoisomerization of chromophores alter equilibrium conformations, the dimensions of the surrounding polymer matrix play an essential role in spatial rearrangements. The dimensional classifications of the matrix effect have been extensively examined [5], with notable applications in ophthalmic lens, optical storage media, photosensors, and biomedical devices. Furthermore, the kinetics of conformational changes of polymers with photochromic moieties depends upon their physical or chemical incorporation into the matrix [6]. As one Handbook of Stimuli-Responsive Materials. Edited by Marek W. Urban

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Photochromic Responses in Polymer Matrices

Ramachandran

Urban

2011

Handbook of Stimuli‐Responsive Materials

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Bleaching kinetics of indoly‐benzylfulgimide in PMMA

Rupp

Zheng

Wang

et al. 2007

Physica Status Solidi (b)

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Indoly‐benzylfulgimide belongs to the photochromic fulgide family and follows photochemical first order kinetics. Its bleaching kinetics is investigated at 633 nm and 640 nm by spectroscopy, by the time dependence of transmission and of diffraction from holographically induced gratings. The non‐exponential decay law resulting for diffraction experiments with a Gaussian beam profile is calculated and verified experimentally. For a quasi‐homogeneous beam profile the time constant determined from diffraction decay is half the one for absorbance decay. The photochemical reaction rate of indoly‐benzylfulgimide in PMMA is (3.9 ± 0.3) cm2/J at 650 nm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

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Absorbance kinetics of dye‐doped systems with photochemical first order kinetics

Rupp¹,

Zheng²,

Menke³

et al. 2007

Physica Status Solidi (b)

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PACS 78.40. Me, 82.50.Hp Often it is assumed that absorbance decays in photochromic materials with the time dependence of the photochemical kinetics, i.e. exponentially for first order kinetics. Although this may hold in the limiting case of vanishing absorbance, deviations are to be expected for realistic samples, because the local photochemical kinetics slows down with increasing initial absorption and penetration depth of the radiation. We discuss the theory of the kinetics of initially homogeneous photochromic samples and derive analytical solutions. In extension of Tomlinson's theory we find an analytical solution that holds with good approximation even for samples that exhibit a small residual absorption in the saturation limit. The theoretical time dependence of the absorbance originating from photochemical first order kinetics of dye-doped systems is compared with experimental data published by Lafond et al. for fulgides doped in different polymer matrices.

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Matrix effects on the photochemical fatigue resistance of fulgide-doped polymers

Cited by 6 publications

References 7 publications

Photochromic Responses in Polymer Matrices

Photochromic Responses in Polymer Matrices

Bleaching kinetics of indoly‐benzylfulgimide in PMMA

Absorbance kinetics of dye‐doped systems with photochemical first order kinetics

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