Synthesis of photoaddressable polymeric networks having azobenzene moieties and alkyl chains-containing compounds

OROFINO, A. B.; GALANTE, M. J.; OYANGUREN, P. A.

POLYMER INTERNATIONAL

JOHN WILEY & SONS LTD

Lugar: Nueva York; Año: 2013 vol. 62 p. 482 - 492

0959-8103

We discuss the synthesis of new optically active polymeric networks containing azobenzene moieties and different alkyl-chain containing compounds. An epoxy resin based on diglycidyl ether of bisphenol A(DGEBA) was reacted with metaxylylenediamine (MXDA). An azo prepolymer (TAZ) was synthesized by reaction between Disperse Orange-3 and DGEBA. Reaction betweenpalmitic acid (PA) and DGEBA was performed using triphenylphosphine as catalyst of the epoxy?acid reaction employing variable molar ratios of epoxy to carboxyl groups (r = 1, 2, 4). These precursors were called PA1, PA2 and PA4. Crosslinked epoxy-based azopolymers containing variable PA-based precursor content and constant chromophore concentration equal to20 wt% TAZ were synthesized. Their reversible optical storage properties were studied and compared. It was found that the optical response is a direct consequence of the morphologies generated, and that crystallization of PA-based precursor can take place. When the PA-based precursor is not covalently bonded to the matrix, e.g. PA1, the remaining birefringence is high.PA4-modifiedmaterials present a completely different response, showing a behaviour that could be of great importance in the development of optical switchers. In this case, the organic tails remain dissolved in the matrix and unable to crystallize, giving a typical ?on?off? response.