Orientational Relaxation of NLO Dipole Moments Transversely Aligned to the Main Backbone in the Linear Polyurethane

Recently, we have synthesized a new type of linear polyurethane (T-polymer) with NLO azobenzene chromophore whose dipole moment is aligned transverse to the main chain backbone and another linear urethane polymer (L-polymer) with NLO dipole chromophore incorporated in the main chain backbone.1 The resultant poled T-polymer shows the large second order nonlinearity of d33=1.6 × 10-7 esu (67 pm/V) with good thermal stability at the ambient conditions.1 This polymer is amorphous with a high density of NLO chromophore moiety and optically transparent thin film, which can be processed by spin-casting or solvent casting.