Spectral study of irgacure 784 dye in an epoxy resin photopolymer

Holographic recording at shorter wavelengths enables to capture holograms with a greater resolution. Photopolymer material sensitisation to a blue or violet wavelength might require replacement of photosensitive dye or whole photosensitiser system which leads to different photoinitiation kinetics. There are known photoinitiator systems which have high values of key photoinitiation parameters, e.g., molar absorption coefficient at a broad range of wavelengths, quantum yield etc. An example of such photosensitiser is an organometallic titanocene, Irgacure 784. However Irgacure 784 in an epoxy resin photopolymer undergoes a complex photo-kinetics which is neither fully understood nor quantified. This complex photo-kinetics results in different bleaching evolution when using green and blue exposing light. The aim of this paper is to identify relevant photo-kinetic reactions taking place during exposure and driving the bleaching process. For this purpose photopolymer layers of four material compositions containing Irgacure 784 were prepared and exposed for nine exposure times. Absorbance spectrum was measured before after each exposure. We report on our experimental results and draw conclusions identifying relevant reactions of the Irgacure 784 photo-kinetics in epoxy resin photopolymers.

[1]  Marcia L. Schilling,et al.  Acrylate Oligomer-Based Photopolymers for Optical Storage Applications , 1999 .

[2]  J. Rabek,et al.  Photoinitiators for visible light polymerization , 1999 .

[3]  J. Sheridan,et al.  Comparison of holographic photopolymer materials by use of analytic nonlocal diffusion models. , 2002, Applied Optics.

[4]  Vicki L. Colvin,et al.  Epoxy Resin-Photopolymer Composites for Volume Holography , 2000 .

[5]  Bernhard Urwyler,et al.  Photochemical Ring Slippage of Bis(pentafluorophenyl)titanocene: Reaction kinetics and matrix isolation of the primary photoproduct , 1988 .

[6]  Shiuan Huei Lin,et al.  An irgacure 784 doped photopolymers for display holograms recording at 532 nm , 2009, Optical Memory and Neural Networks.

[7]  Yusuf Yagci,et al.  Photoinitiation of cationic polymerization by visible light activated titanocene in the presence of onium salts , 2001 .

[8]  Michael R. Gleeson,et al.  Nonlocal photopolymerization kinetics including multiple termination mechanisms and dark reactions. Part I. Modeling , 2009 .

[9]  Yasuo Tomita,et al.  Improved thermal stability of volume holograms recorded in nanoparticle--polymer composite films. , 2008, Optics letters.

[10]  Shiuan Huei Lin,et al.  Preparation and characterization of Irgacure 784 doped photopolymers for holographic data storage at 532 nm , 2009 .

[11]  Yasuo Tomita,et al.  Order-of-magnitude polymerization-shrinkage suppression of volume gratings recorded in nanoparticle-polymer composites. , 2010, Optics letters.

[12]  Robert R. McLeod,et al.  Absorption and bleaching dynamics of initiator in thick photopolymer exposed to Gaussian illumination , 2008, Organic Photonics + Electronics.

[13]  R. Sastre,et al.  The efficiency of titanocene as photoinitiator in the polymerization of dental formulations , 2003, Journal of biomaterials science. Polymer edition.

[14]  Dusan Sabol,et al.  Photoinitiation study of Irgacure 784 in an epoxy resin photopolymer , 2010 .

[15]  Justin R. Lawrence,et al.  Photopolymer holographic recording material , 2001 .

[16]  Anna C. Balazs,et al.  Nanoparticle Polymer Composites: Where Two Small Worlds Meet , 2006, Science.

[17]  Michael R. Gleeson,et al.  Examination of the photoinitiation processes in photopolymer materials , 2008 .

[18]  Michael R. Gleeson,et al.  The production of primary radicals in photopolymers during holographic exposure , 2010 .