Synthesis and incorporation of ladder polymer subunits in copolyamides, pendant polymers, and composites for enhanced nonlinear optical response

Several electroactive polymers, such as polyacetylene, polythiophene, poly [p-phenylene vinylene] and poly [2,5-thienylene vinylene] have shown promise as NLO-active materials over the past few years. However, as several theoretical and experimental research groups have pointed out in recent publications and symposia, it is not evident that long conjugation lengths are necessary for enhanced χ⁽³⁾ activity. As recently demonstrated, copolyamides which incorporate polyenylic or PTV oligomeric repeat units show χ⁽³⁾/α values of ca. 10^-13 esu-cm at 532 nm(band-edge). In this paper, the authors discuss how ladder subunits related to the electroactive polymers POL and PTL can be incorporated into polymer films as (a) copolymer repeat units, (b) pendant groups attached to poly [p-hydroxystyrene] and (c) guest-host composites in polycarbonate. Sharp optical absorptions are found in all cases as well as promising χ⁽³⁾ properties.