AbstractNew polyurethanes containing Y‐shaped chromophores, symmetrical derivatives of 4‐(dicyanomethylene)‐2‐methyl‐6‐[p‐(dimethylamino)styryl]‐4H‐pyran, have been prepared. The polymers show high glass transition temperatures (Tg) and a good thermal stability. SHG measurements on poled polymer films of the synthesized polymers have been carried out and a maximum d33 of 15 pm · V−1 has been found at 1 368 nm fundamental wavelength. Time stability measurements on the most active polymer have shown that after the initial fast relaxation, the d33 value remains constant at 80 °C for 60 d.magnified image