Self assembled asymmetrically substituted polydiacetylene as a novel second order NLO material

Polymer chains of a novel asymmetric polydiacetylene, poly((8-butoxy carbonyl)methyl urethanyl) 1-(5-pyrimidyl)-octa-1,3-diyne(BPOD) self assemble in an acentric stable polar organization upon spin coating. Spontaneous alignment of the urethane moiety caused by the intramolecular hydrogen bonds between the side groups appears to be responsible for this organization. An abrupt decrease of SH intensity at around 130 °C is found to be closely related to the breaking of noncentrosymmetry in the films in conjunction with the disruption of these intramolecular hydrogen bonds. Dielectric and infrared spectroscopy confirm the relaxation of the stable hydrogen bonded polar organization at higher temperatures.