Optical-limiting and nonlinear optical polyacetylenes: Synthesis of azobenzene-containing poly(1-alkyne)s with different spacer and tail lengths

Poly(1-alkyne)s containing azobenzene pendant groups with different lengths of the spacer and terminal alkyloxy group {-[HC=C(CH2)(m)OCO-C6H4-N=N-C6H4-OCpH2p+1](n)- , where m = 1, 2, 3, or 9 and p = 4, 7, or 121 were synthesized in satisfactory yields with the [Rh(nbd)Cl](2)-Et3N catalyst. All the polymers were soluble in common organic solvents such as CHCl3 and tetrahydrofuran. Their structures and properties were characterized and evaluated with IR, NMR, thermogravimetric analysis, UV, and optical-limiting and nonlinear optical analyses. All the polymers were thermally stable and decomposed at temperatures as high as similar to 300 degrees C. The optical-limiting and nonlinear optical properties of the polymers were sensitive to their molecular structures. Polymers having shorter spacer lengths and longer terminal groups showed better performances and larger third-order nonlinear optical susceptibility (up to 1.34 x 10(-10) esu). (c) 2006 Wiley Periodicals, Inc.