Structural control of the side-chain chromophores to achieve highly efficient nonlinear optical polyurethanes

Two series of polyurethanes (P1-P10) containing NLO chromophores as side chains were prepared, in which the size of isolation groups was changed from small atoms to much larger groups such as carbazolyl groups. The polymers were well characterized. The tested NLO properties of the polymers demonstrate that the NLO values and the poling efficiency of the polymers are not always improved with increasing of the size of isolation spacer, and for a given chromophore moiety, there is a suitable isolation group present to boost its microscopic beta value to possibly higher macroscopic NLO property efficiently.