As part of our continuing effort in developing high Tg, photoresponsive amorphous polymers, five new bis(azobenzene)-containing diamines (azoDM) were synthesized via multiple-step routes to vary degrees of flexibility and bulkiness of connecting groups (Ar”. Fig.1), such as ether, thiol and cardo-9,9-fluorenyl, between the two azobenzenes. They were polymerized with five different commercial dianhydrides: pyromellitic dianhydride (PMDA), 3,3’,4,4’-benzophenone tetracarboxylic dianhydride (BTDA), oxy-4,4’-di(phthalic anhydride) (ODPA), 1,1,1,3,3,3-hexafluoro-2,2-bis(4-phthalic anhydrido)propane (6FDA) and 2,2-bis[4-(3,4-dicarboxyphenoxy) phenyl]propane dianhydride (BPADA) to afford five series of high Tg, linear polyimides containing two azobenzenes per repeat unit. All the polymers displayed high thermo-oxidative and thermal stabilities (&gt;400 °C in both air and nitrogen) and high Tgs (&gt;200 °C). Their morphology and mechanical properties were measured by WAXD and DMA, respectively. The photo-directed bending of cantilevers composed of these materials will be examined upon exposure to linearly polarized 445 nm light, and the effect of the azoDM linkages on their photomechanical responses will be investigated.

Synthesis and structure-property relationship of novel azobenzene-containing diamines and polyimides

249th National Meeting (2015)

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