Abstract
A new second-order nonlinear optical (NLO) polyimide (PI) with high thermal stability has been developed The PI was prepared by the ring-opening polyaddition of 4, 4′-(hexafluoroisopropylidene)diphthalic anhydride with a new diamine with two Disperse Red-I units, followed by poling during andafter the thermal imidization process. The glass transition temperature of PI was 182°C. The second harmonic coefficient (d33) of PI at the wavelength of 1.06μm was 116pm/V (278.6×10-9 esu) and remained unchanged at elevated temperatures. The corona poling process of the NLO substituted poly(amic acid) to the PI was also studied in detail by measuring the second harmonic generation (SHG) from the polymer films.
