Rheological study of some photo-response stimuli azo-polysiloxanes

作者：Nor I^*; Ene R; Hurduc V; Bercea M

来源：Journal of Optoelectronics and Advanced Materials, 2008, 10(3): 683-688.

• ATRP
• polysiloxanes
• azobenzene
• photo-isomerization

Polymers with azo groups in the main or side chain have aroused a great interest due to the possibility of conformational modification under UV irradiation, This properly can be exploited in the field of data storage, drugs controlled release, in holographic technique, etc. In the present study we have synthesized and investigated a series of compounds with azo groups, namely: poly (styrene-ran-cloromethylstyrene) graft on a cyclic polysiloxane. More of than, some linear azo-polysiloxanes were modified too, with thymine groups. It was also tested the possibility to emphasize by means of rheological measurements the conformational modification of these compounds under UV irradiation. For the investigated samples, a sharp variation of the viscoelastic parameters (the elastic modulus, the loss modulus, the complex viscosity and the loss tangent) was observed. This variation occurs over several decades (more than four orders in magnitude). This behaviour can be associated with the conformational changes induced by trans/cis isomerization given by the azobenzenic groups. An association of polymer chains due to the changes of the azo-groups dipole-moment on the macromolecular chain can also occur.

• 出版日期2008-3