Optical data storage azobenzene polymers

PHOTOCHROMIC POLYMERS FOR OPTICAL DATA STORAGE AZOBENZENES AND PHOTODIMERS... 

Very recently, the azobenzene norbornene derivative XI (Scheme 2) was successfully prepared and polymerized with initiator 5 and 9, and it showed a nematic mesophase. The polymer was photo-switchable due to photo cisltrans-isomerization of the N=N double bond [65]. This is the first step towards ROMP-derived materials that may be used for optical data storage. 

This chapter discusses photochromic azobenzene polymers and photochromic molecules capable of undergoing photodimerization as materials for potential use in optical data storage applications. A brief introduction to photochromism, including recent examples of some photochromic systems, other than azobenzenes, based on variety of applications is presented at the outset. Thereafter, we shall focus on azobenzene photoaddressable polymers (PAPs) and [4 + 4]-photocycloaddition as materials for ultrahigh capacity optical data storage. 

We shall now embark on the main focus of this chapter photochromic azobenzene polymers and photochromic materials capable of undergoing photodimerization for potential use in optical data storage applications. Herein, the photochromic polymers described are those in which the photochromic molecule is covalently linked, either as part of the main chain or as a side-chain, to the polymeric system. 

Amorphous polymers with pendant azobenzene groups were demonstrated to be good candidates for optical data storage and other electrooptic applications. One such material can be illustrated as follows ... 

Other complex architectures, such as azobenzene star polymers (Angiolini et al, 2006) and molecular brushes (Lee et al, 2006a), have also been prepared, although their optical data storage capabilities have not yet been explored. Advances in these new macromolecular architectures are generally based on the combination of CRP and click chemistry reactions as a synthetic tool for achieving more complex smart polymers. 

Smart photoaddressable polymers containing azobenzene units have been actively investigated over more than two decades as media for optical data storage. Information can be recorded in these materials, through the effect of... 

A large number of azobenzene-based amorphous and liquid crystalline polymers, particularly polyacrylates and polymethacrylates with chiral azobenzene pendants, have been prepared for the development of data storage and photonic devices [1-3,11-14]. For instance, the introduction of optically active mesogenic azobenzene residues into the side groups of the polymers produces chiral nematic and cholesteric phases, which are regulated by photoisomerization of the azobenzene units [10,14]. In most cases, however, the optical activity and chiroptical... 

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