Photoresponsive polymers synthesis

The 2,4,6-triisopropylbenzophenone chromophore has been incorporated into a polymer in order to examine whether the photocyclisation to a benzocyclobutenol could be used as the basis for a photoresponsive polymer material. Benzocyclobutenol formation has also been used to prepare a potential synthon for the synthesis of podophyllotoxin thus benzophenones (384) have been converted to benzocyclobutenols (385). The reaction is highly regioselective and yields the stereochemistry expected from thermal electrocyclic ring closure of an E,E enol (386), which is in agreement with the conclusions of Wagner described above. 

H. Kamogawa, Synthesis and properties of photoresponsive polymers, Progr. Polym. Sci. Japan... 

Synthesis of a Photoresponsive Polymer and Its Incorporation into an Organic Superlattice... 

Nishikubo, T., Kameyama, A., Kishi, K., Kawashima, T., Fujiwara, T., and Hijikata, C., Synthesis of new photoresponsive polymers bearing norbomadiene moieties by selective cationic polymerization of 2- [ [ (3-phenyl-2,5-norbomadienyl)-2-carbonyl] oxy] ethyl vinyl ether and photochemical reaction of the resulting polymers. Macromolecules, 25,4469-4475,1992. 

Nagai, X, Shimada, M., and Nishikubo, X, Synthesis of new photoresponsive polymers containing trifluoromethyl-substituted norbomadiene moieties, Chem. Lett., 1308-1309, 2001. 

In general, the polymers with polyconjugated systems of double and triple bonds are photoeonductive in the UV and at least part of the visible range. In some cases the photoresponse extends to the near infrared range. Although their usefulness in practical applications has been many times suggested, the results have been more or less disappointing. The main problems still remain difficult synthesis, in most cases poorly identified structure, and with few exceptions insolubility and intractability of the polymers. The direct comparison with poly(N-vinyl carbazole) and other photoeonductive polymers is not possible for lack of comparative data. 

It is not necessary to carry out synthesis, if the triggering photochromic compound has good affinity to the polymer matrix. A mixture of the polyacrylate with BMAB which exhibits an excellent function as trigger is equally photoresponsive. While the monomer model compound (i.e. the acrylate before polymerization) does not provide a liquid crystalline phase, the polymer shows a clear nematic - isotropic transition at ca. 61 °C and the glass transition temperature at 24 °C as shown in Fig. 4. Tj j depends very much on the length of the alkyl spacer. In comparison with the... 

Izumi A, Teraguchi M, Nomura R, Masuda T. 2000b. Synthesis of poly(p phenylene) based photoresponsive conjugated polymers having azobenzene units in the main chain. Macromolecules 33(15) 5347 5352. 

Momotake A, Arai T. 2004b. Synthesis, excited state properties, and dynamic structural change of photoresponsive dendrimers. Polymer 45(16) 5369 5390. 

Yamamoto H, Nishida A. 1991. Photoresponsive peptide and polypeptide systems. Part 9. Synthesis and reversible photochromism of azo aromatic poly(L a,g diaminobutyric acid). Polym Int 24(3) 145 148. 

Zhang Y, Cheng Z, Chen X, Zhang W, Wu J, 23m J, Zhu X. 2007. Synthesis and photoresponsive behaviors of well defined azobenzene containing polymers via RAFT polymerization. Macromolecules 40 4809 4817. 

Burts AO, Gao AX, Johnson JA. Brush-first synthesis of core-photodegradable miktoarm star polymers via ROMP towards photoresponsive self-assemblies. Macromol Rapid Commun. 2014 35 168-73. 

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