Promotion of the second-order nonlinear optical effect by introducing ether linkage into polymer main chains

Second-order nonlinear optical (NLO) linear-dendritic (L-D) copolymers were designed and successfully prepared by the combination of a dendritic chromophore and an alkyl chain (P1) or alkoxy chains (P2-P5). Thanks to the lower rotational barrier of the ether bond than that of the single carbon-carbon one, much enhanced macroscopic NLO performance, as characterized by d(33) values, was achieved with the highest value of 166 pm V-1, approximately 1.8 times that of P1 (94 pm V-1). This finding opens up a new approach to the efficient control of the poling efficiency of chromophore moieties by subtle modifications to boost the NLO performance of polymeric materials as high as possible.