Poling Dynamics and Negligible Relaxation in Aromatic Polyurea Studied by In Situ Observation of Second-Harmonic Generation

Abstract
The poling process has been observed by means of second-harmonic generation in aromatic polyurea prepared by vapor deposition polymerization. Polymerization from the as-grown oligomer and crystallization proceed simultaneously with an electric-field-induced alignment of the urea group at about 130°C. Consequently, the poled structure is thermally quite stable even at 200°C and shows negligible relaxation at room temperature.