O-ésteres de alfa-oxooximas. Síntesis, estudio fotoquímico y evaluación como fotoiniciadores de polimerización

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química. Fecha de lectura: 09-05-199

Theoretical and experimental study of the bleaching of a dye in a film-polymerization process

The quantum efficiency and the molar-absorption coefficients of different phenothiazine dyes are obtained by means of fitting the experimental data of transmittance as a function of time. An analytical expression for the intensity transmitted in a photopolymerizable holographic material is obtained, and good agreement between theory and experience is also achieved. The analysis of these parameters is of fundamental quantities in the photochemical characterization of holographic recording materials.This study was supported by the Direcció General d'Ensenyaments Universitaris i Investigació de la Generalitat Valenciana, Spain (Project GV-C-CN-06-064-96)

On the polymerization of 2-aminodiphenylamine: an electrochemical and spectroscopic study

The electrochemical oxidation of 2-aminodiphenylamine (2ADPA) was performed by cyclic scanning of the potential in aqueous HCl solutions. A mixture of oligomeric compounds, named poly(2ADPA), was deposited on the surface of the electrode. The chemical structures present in poly(2ADPA) containing phenazine units and open-ring units were assigned by 1H NMR spectroscopy. CV results revealed that the redox transformation of poly(2ADPA) from the fully reduced to the fully oxidized state occurs under a single voltammetric peak. The SEM images obtained for the polymer deposited on platinum substrates showed a “fallen leaves” morphology. In situ FTIR spectroscopy experiments carried out during the reversible oxidation of the polymer revealed that the conversion of aromatic rings (1500 cm−1) into quinoid structures (1524–1590 cm−1) is of major significance. Besides, the transformation of secondary aromatic amines (1301 cm−1) into fully oxidized imines and polaronic structures (1470, 1389, 1330 and 1250 cm−1) has been observed.Ministerio de Ciencia y Tecnlogía (MAT2004-1479); Comisión Europea (Fondos ERDF)

Holographic photopolymer with pentaerythritol triacrylate

New holographic recording material based on photopolymerizable systems have contributed significantly to recent growth of holographic applications. Previously, we report that on photopolymerizable system with the presence of the difunctional monomer, ethylene glycol dimethacrylate improves the behavior of the system and particularly to elucidate the role played by eosin ester with oxooxime group in the production of amine initiator radicals. This comparative study has been carried out in our laboratory using differential scanning photocalorimetry and holography. The results of the new photosensitive recording material for holography indicate that this system can be used for the formation of very promising photopolymer with better performance. The aim of this work has been changed the crosslinking monomer to decrease the energetin sensitivity and know the rest of the behavior. The new photopolymerizable mixture containing pentaethritol triacrylate in the same relation with the ethylene glycol dimethacrylate mixture. A diffraction efficiency of 80% is achieved with a energetic sensitivity of 3 J/cm2 at 514 nm, and the spatial resolution is up to 2000 l/mm.This work was financially supported by the Comisión Interministerial de Ciencia y Tecnología (CICYT) of Spain (projects MAT93-0369 and MAT91-0488)

Mechanical behavior of holographic material in a high vacuum and with temperature changes

Evaluation of the mechanical properties of films of the materials currently employed for recording diffractive optical elements is very important in order to foresee their mechanical behavior during the photochemical processing following recording of the interference pattern. This will also provide information about the mechanical and thermal stability of holograms recorded on these materials, which may be tested in the different environments in which the final application of the optical elements will be used. For quantitative evaluation of these properties in an acrylamide based photopolymeric system, a study was carried out on layers of films of polyvinylalcohol and polyvinylalcohol mixed with triethanolamine. Layers coated on glass substrate were subjected to both a high vacuum and temperature changes. Real time measurements of optical path variations in the film were performed using a vacuum interferometric measurement system.This work was financed by IMPIVA and by Direcció General d'Ensenyaments i Investigació (Generalitat Valenciana, Spain), project GV-C-CN-06-064-96

Comportamiento termomecánico en alto vacío del PVA como material para holografía

Este trabajo ha sido financiado por el IMPIVA y por la Direcció General d'Ensenyaments i Investigació de la Generalitat Valenciana (Proyecto GC-C-CN-06-064-96)

Study of mechanical and thermal behaviour of an optical material

El conocimiento de las propiedades mecánicas de los materiales utilizados comúnmente para el registro de elementos ópticos difractivos es de gran importancia para predecir su comportamiento mecánico durante el procesado fotoquímico al que se les somete durante el grabado del patrón interferencial. Esto también proporcionará información sobre la estabilidad mecánica y térmica del holograma almacenado en estos materiales en los diferentes entornos en los que será aplicado definitivamente. Para evaluar cuantitativamente estas propiedades en un sistema fotopolimérico basado en acrilamidas se realizó un estudio sobre capas de polivinilalcohol (polímero soporte del sistema fotopolimérico). Las capas previamente depositadas sobre un sustrato de vidrio se sometieron a alto vacío y posteriormente a un cambio de temperatura. Las medidas en tiempo real de las variaciones de camino óptico sufridas por la capa se obtuvieron usando un sistema de medida interferométrico en alto vacío.Evaluation of the mechanical properties of films of the materials currently employed for recording diffractive optical elements is very important in order to foresee their mechanical behavior during the photochemical processing following recording of the interference pattern. This will also provide information about the mechanical and thermal stability of holograms recorded on these materials, which may be tested in the different environments in which the final application of the optical element will be used. For quantitative evaluation of these properties in an acrylamide based photopolymeric system, a study was carried out on layers of films of polyvinyalcohol. Layers coated on glass substrate were subjected to both a high vacuum and temperature changes. Real time measurements of optical path variations in the film were performed using a vacuum interferometric measurement system.Este trabajo fue financiado por el IMPIVA y por la Direcció General de Ensenyaments i Investigació de la Generalitat Valenciana (Proyecto GV-C-CN-06-064-96)

High-energy sensitivity enhancement in panchromatic photopolymers for holography using a mixture of visiblelight photoinitiators

A new aqueous photopolymer containing the monomers acrylamide, N,N'-methylenbisacrylamide and zinc acrylate, the initiators 4,5-diiodosuccinylfluorescein (2ISF) and methylene blue (MB), and the coinitiator sodium p-toluenesulphinate is described. This formulation exhibits a clear enhancement of the high-energy sensitivity upon irradiation with 514 or 633 nm light (Ar+ laser or He-Ne laser respectively), with respect to the same mixture but with only one of the two dyes, reaching maximum diffraction efficiencies of 15-20% with 15-60 mJ cm-2. This enhancement is explained by the more efficient photogeneration of initiator radicals by the ground-state formation of an ion-pair complex between cationic (MB) and anionic (2ISF) chromophores. This must compensate the observed decrease in the absorbance of the mixture of the two dyes at 514 nm, with respect to the absorbance of the same medium but with only 2ISF (maximum absorption at 490 nm). A clear absorbance increase at 633 nm, with respect to the absorbance of this system with only MB (maximum absorption at 660 nm), must also favour photopolymerization.This work was supported by the CICYT, Spain, under projects MAT93-0369 and MAT94-0757

Study of the quantum yield and molar absorptivity for a dye photobleaching in a holographic recording material

The quantum efficiency and molar absorption coefficients of dyes are the responsible for holographic efficiency and sensitivity in a photopolymeric holographic recording material. These parameters have been obtained by fitting the experimental transmittance curves as function of time. For this using the mechanism of photo initiation an analytical expression for the transmitted intensity in a photopolymerizable holographic material has been proposed, obtaining good agreement between theory and experience.This work was supported by the Direcció General d'Ensenyaments Universitaris i Investigació de la Generalitat Valenciana, Spain (Project GV-C-CN-06-064-96) and to the commission interministerial de Ciencia y Tecnología (CICYT) of Spain for financial support project MAT96-1767-E

Optimal composition of a holographic recording material

We study the effect of the addition of a crosslinking agent in a photopolymerizable matrix for real time holography. The optimization of the concentration of this component has been realized attending to the holographic parameters like energetic sensitivity and diffraction efficiency. Diffraction efficiencies near to 80 percent have been obtained with energetic exposures of 12 mJ/cm2.Research Project PTR-0115 (CICYT); Project MAT96-1767-E