Highly efficient UV-absorbing thin-film coatings for protection of organic materials against photodegradation

Abstract

UV-protective coatings have been prepared by the sol-gel method, to reduce the destructive effects of UV radiation on easily photodegradable devices, i.e. those containing organic compounds, such as dyes and pigments or plastic materials to be used in outdoor applications. A benzophenone derivative (2,2-dihydroxy, 4-methoxybenzophenone), showing high photostability and strong absorption in the UV range, was embedded in an ormosil matrix. The usage of an organically modified silica matrix enhances the solubility of the UV absorber in the matrix allowing the preparation of highly loaded coatings. The protective coatings, prepared at room temperature, require no thermal treatment after deposition, allowing therefore their application on temperature sensitive materials. The resulting films have a strong absorption in the UV range with a thickness of only 1.0 mm. In addition, the UV-absorbing coatings are transparent, colourless, and exhibit high optical quality. The UV-protective coatings offer an easy method to prevent the photodegradation of organic materials without altering their optical properties in the visible region.Fluorescent rhodamine dye-doped thin ormosil films were coated with a UV-protective layer in order to study their effectiveness in the reduction of the photodegradation of the dye upon irradiation with UV light. The degradation of 20% of the molecules in coated samples was 14 times slower than that of the uncoated samples. The effective temperature range of the UV-protective coatings was established by measuring the photodegradation of the samples at different temperatures.

Template free preparation of nanoporous organically modified silica thin films on flexible substrates

“…Also, we observed that the hydrophobicity of the paper substrate is stable and there is no significant change in the contact angle even after 25 cycles of bending (bending radius is 2.5 mm). Fig.9b shows the contact angle of the films is stable over the whole pH range (pH [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. There is a slight decrease (6 ) in the contact angle at pH 14 but still the surface is hydrophobic with a contact angle of 117 .…”

“…As a result of this unique property, they are ideal materials for anticorrosion, antifouling and fire retardation applications. [3][4][5][6][7][8] Furthermore, nanoporosity is added to ormosils in order to provide extra-functionalities such as high surface area [9][10][11] and therefore adsorption capacity, 12,13 and very low refractive index 14,15 and dielectric constant. 16 Nanoporous ormosil bulk materials and thin films can be prepared using selfassembling template molecules to form periodic nanopores 17 or by sacrificial polymers to induce nano-phase separation.…”

Luminescent 3-hydroxyflavone nanocomposites with a tuneable refractive index for photonics and UV detection by plasma assisted vacuum deposition

“…Thanks to this quality different kind of ESIPT dyes have been used for the development of UV protective coatings. 62 In case of 3-HF containing materials it have been reported that the dye photostability depends on the characteristics of the surrounding media. 73 The fitting of the luminescent decay curves demonstrates that the dye is trapped in different microenvironments that affect their luminescent properties (i.e.…”

Impact of nanostructured thin ZnO film in ultraviolet protection

“…In addition, UV radiation-induced damage can be associated with the discoloration of dyes and pigments, weathering, yellowing of plastics, and loss of gloss and mechanical properties (cracking) as well. 2 Consequently, several products must be protected to sustain long periods under UV radiation. [3][4][5] Therefore, the study and development of UV-protective materials has become a very important issue.…”