Langmuir-Blodgett Film of a Processable Polydiacetylene with Tricyanovinyldialkylaniline Chromophore

Abstract

ABSTRACTA soluble and processable polydiacetylene (PDA) with functionalizable N,N-dialkylaniline and glutamate ester substituted alkylurethane side groups was synthesized. This PDA was further reacted with tetracyanoethylene to effect postpolymerization functionalization. This new strategy further functionalizes conjugated polymers and introduces a tricyanovinyl (TCV)-aniline chromophore. The resulting polymer was soluble in common organic solvents. Asymmetric multilayers of the tricyanovinylated PDA were fabricated using the Langmuir-Blodgett (LB) technique. Thickness, visible absorption, and second harmonic (SH) intensity were found to increase linearly as a function of the number of layers. Polarized UV-visible and IR studies revealed that the main chain preferentially orients vertical to the compression direction with out-of-plane orientation of the TCV-aniline group with respect to the glass substrate. The resonant enhanced second-order nonlinear optical (NLO) coefficient (d33) of the 20 LB layers was found to be 21 pm/V at 1.064 µm, while no SHG signal was observed for cast or spincoated films.