New second-order nonlinear optical polyphosphazenes: Convenient postfunctionalization synthetic approach and application of the concept of suitable isolation group

The concept of suitable isolation group was applied to the synthesis of nonlinear optical polyphosphazenes that contained different isolation groups attached to the side chains of polyphosphazenes using a post-functional strategy. The loading density of NLO chromophore moieties in the polymers was relatively high (0.60 per unit) and all polymers displayed good processability and relatively good NLO effects, as exemplified by an SHG coefficient (d33) of 67.3 pm V−1 recorded for the polyphosphazene that contained the largest isolation group.