Photochemical Effect of Azocompounds Acrylates Grafted in Different Polymeric Matrices G. Burillo ( ), E. Bucio, M. del P. Carreón-Castro and S. Castillo-Rojas Instituto de Ciencias Nucleares UNAM, Ciudad Universitaria, 04510 México, D. F. E-mail: burillo@nucleares.unam.mx Received: 30 March 2005 / Accepted: 21 July 2005 Published online: 8 August 2005 – © Springer-Verlag 2005 Summary Acrylate side chains containing a photocromic azobenzene group (Disperse Red 1, DR1) grafted onto different polymer matrices: polypropylene (PP), low density polyethylene (PE), polyethyleneterephthalate (PET) and polycarbonate CR-39 (PC), were prepared by gamma radiation of polymer films in toluene solutions of acryloyl chloride in Pyrex ampoules sealed in vacuum, and then esterified with DR1 in presence of triethylamine. Comparison of photochemical properties of the different systems, as well as thermal stability and surface morphology were studied. Introduction Optically active methacrylic homopolymers with side-chain azobenzene chromophores have been studied in solution, and kinetics of the trans-cis photoisomerization of the azo-aromatic double bond has been measured by Angiolini [1], photochromic side chain liquid crystalline polymethacrylates containing paranitroazobenzene group were synthetized and characterized by Zhang [2]. Polymers containing azobenzene chromophores possessing interesting properties such as the possibility of direct formation of surface relief gratings among others, have attracted considerable attention in the last decade [3-5]. Some azo polymers have been synthetized in recent years and they were studied for the photo-fabrication of surface relief gratings (SRG) [6-9]. He [10] synthetized a novel polymer containing azobenzene chromophores in the main and side chains and studied the thermal and photochemical properties. The effect of photobleaching in polymer films containing azo dyes was studied by different authors [11-14]. Hattori [14] reported that the absorption the band at around 485 nm from the DR1 molecule in the film of PMMA decreased under exposure to UV light in function of time and completely disappeared after 7 h, and a new band appeared at around 370 nm which corresponds to a molecule of p-nitroaniline which means that the decomposition of the azo group of DR1 molecule occurs during UV light exposure. The general reaction of photobleaching with UV radiation is show in scheme 1. The purpose of this paper is to show that azocompounds grafted in polymeric systems are photosensitive as small azocompounds in solutions or polymers containing this group. Liquid systems of azocompounds present instability to UV light and grafted Polymer Bulletin 55, 191–199 (2005) DOI 10.1007/s00289-005-0427-9