High glass transition chromophore functionalised polyimides for second-order nonlinear optical applications

Nonlinear optical (NLO) polymers with glass temperatures (T-g) as high as 2 91 degreesC were prepared, PI 2-4 by covalent bonding of a chromophore to t he backbone of hydroxyl polyimides via a Mitsunobu reaction, PI 1 as a dono r-embedded polyimide was synthesised by polycondensation of a diaminochromo phore and 4,4'-(hexafluoroisopropylidene) diphthalic anhydride in a two-ste p reaction. Poled films of the polymers were measured for their second-harm onic generation (SHG) effect and showed d(33) Values up to 20 pm/V. Some of the films show a stable nonlinear optical response even to 90% of remainin g NLO-intensity at 125 degreesC during 200 h. (C) 2001 Elsevier Science Ltd . AU rights reserved.