Soluble functional polyacetylenes for optical limiting: Relationship between optical limiting properties and molecular structure

Four polyacetylenes containing chromophores with different conjugation bridge structure or terminal substituents were designed and prepared by using [Rh(nbd)Cl]2 as catalysts, respectively. Their structures and properties were characterized and evaluated by IR, NMR, UV, TGA, optical limiting and nonlinear optical analyses. All the polymers show high thermal and photo stability and novel optical limiting properties. The functional polyacetylene with stilbene pendant shows better optical limiting property than that with azobenzene chromophore pendant. Their optical limiting mechanisms are mainly originated from reverse saturable absorption of molecules. Their nonlinear optical properties are significantly affected by their molecular structures and the shorter spacer group will be beneficial in increasing the electronic interaction between chromophore pendant and polyacetylene conjugation backbone to result in higher third-order optical nonlinearity.