Preparation and nonlinear optical properties of two acrylate polymers bearing different long conjugated pendants

Two new acrylate monomers containing different long π-election conjugation bridge structure, 4′-(N,N-diethylacrylate) amino], 4-(pyridine-4-vinyl) stilbene (DAS) and 4′-(N,N-diethylacrylate) amino], 4-(pyridine-4-vinyl) azobenzene (DAA), were synthesized and their copolymers with methyl methacrylate (MMA) were prepared by free radical polymerization method. Their structures and properties of these copolymers were characterized and evaluated by FTIR, ¹H-NMR, UV spectra, GPC and Z-scan technique with 8 ns pulses at 532 nm wavelength. The relationship between their structures and properties was investigated. The results show that the structure of these resultant copolymers can be effectively tuned by simply varying the feed ratio and these copolymers exhibit good solubility and large third-order nonlinear optical properties. The large third-order nonlinear optical properties are mainly attributed to the substituted NLO-chromophore with long D-π-A conjugated structure. Simultaneously, it is found that poly (DAA-co-MMA) with N=N double bond as conjugation bridge has larger third-order nonlinear optical susceptibility than poly (DAS-co-MMA) with C=C double bond as conjugation bridge owing to more effective π electron conjugation effect.