IR Reflectivity Change from Electroactive IPN.

A promising alternative of multi-layered devices showing electrochromic properties results from the design of a self-supported semi-interpenetrating polymer network (semi-IPN) including an electronic conductive polymer (ECP). The formation of the ECP in the network has already been described by oxidative polymerization using iron trichloride as an oxidant and leading to conducting semi-IPN with mixed electronic and ionic conductivities as well as convenient mechanical properties. This work relates to the elaboration of such semi-IPN using a PEO/NBR (Nitrile Butadiene Rubber) IPN in which a linear poly (3, 4-ethylenedioxythiophene) (PEDOT) is formed symmetrically and selectively as thin layers on the two sides of the film matrix. PEO/NBR/PEDOT semi-IPNs lead to interesting optical reflective properties in the IR between 0.8 and 25 μm. Reflectance contrasts up to 35% are observed when, after swelling in an ionic liquid, a low voltage is applied between the two sides of the film. The PEO/NBR IPN as a thin film possesses both a good flexibility and a good resistance against thermal ageing compared with a single PEO network previously employed. Moreover, the combination of NBR and PEO in an IPN leads to materials possessing a good ionic conductivity at 25°C. Finally, NBR/PEO/PEDOT semi-IPNs allow observing comparable reflectance contrast in the IR range than those previously shown by PEO/PEDOT semi-IPNs. [ABSTRACT FROM PUBLISHER]