Azo-dye side-chain polymers

Sawodny, M., Schmidt, A., Urban, C., Ringsdorf, H., and Knoll, W. Photoreactions in Langmuir-Blodgett-Kuhn Assemblies of Liquid Crystalline Azo-dye Side Chain Polymers, Prog. Colloid Polym. Sci. 89,165 (1992). 

M. Sawodny, A. Schmidt, C. Urban, H. Ringsdorf, and W. Knoll, Photoreactions in Langmuir-Blodgett-Kuhn multilayer assemblies of liquid crystalline azo-dye side-chain polymers, Prog. Colloid Polym. Sci. 89, 165-169(1992). 

The concept of cis-trans isomerization in azo-dye side-chain polymers was developed by Shibaev et al. [11]. The side chain of the polymer was made of azobenzene side groups (Figure 2.2). After illumination with UV light the following transformation occurs [33] (Figure 2.2) ... 

The side-chain polymers used by Shibaev et al. are also shown in Figure 2.2. The increase of the molar percentage of the azobenzene moiety results in a higher order of the azo-dye fragments. The order parameter of the azo-dye side-chain polymers cannot be very high, however, as it can be considerably increased when the annealing of the photo-oriented azo-dye side-chain polymer is used above the glass transition temperature [34]. Theoretical approaches that describe cis-trans... 

The first generation NLO polymers were side chain polymers, usually made by copolymerisation of a monomer bearing the chromophore bridged by a flexible spacer group with a co-monomer, commonly methacrylates. This is a flexible process allowing a wide range of co-polymers to be made. A typical example of this type of polymer is the methyl methacrylate azo dye co-polymer (5.9). 

Side Chain Polymers. Dye-substituted polymers were synthesized with azo or stilbene dyes incorporated into a transparent polymer matrix at the side chain of methacrylate or acrylate polymer with high dye contents. The azo and the stilbene dyes have a 7C-electron conjugated system with acceptor and donor substituent groups at both ends of their molecules. 

Four main mechanisms of the photoalignment are known (i) reversible photochemical trans-cis isomerization in azo-dye-containing polymers, monolayers, and pure dye films (ii) pure photophysical reorientation of the azo-dye chro-mophore molecules (iii) topochemical crosslinking in cinnamoyl side-chain polymers (iv) photodegradation in polyimide materials. 

Polymers 159, which contain cationic (arene)Fe(77 -C5H5) units in the main chain together with azo dyes in the side-group structure, have also been developed (Scheme 15). Photolysis in the presence of H2O2 led to photobleaching. 

Sekkat Z, Kang C S, Aust EF, Wegner G, Knoll W. 1995a. Room temperature photo induced poling and thermal poling of a rigid main chain polymer with polar azo dyes in the side chain. Chem Mater 7(1) 142 147. 

Iron-Containing Polymers with Azo Dyes in their Side Chains or Backbones... 

Synthesis of Organoiron Polymers Containing Azo Dyes in Their Side Chains. 174... 

Polymerization of 5 gave organoiron polymers containing azo dyes in the side chains. The polymers (7, 8, 9) were prepared by nucleophilic aromatic substitution reactions between 5 and various O- and S- containing dinulceophiles (Scheme 7.3). 

---