Synthesis and photoreactions of polyesters containing triazene and cinnamylidene malonyl units

Abstract

The synthesis and photoreactions of polyesters containing the photolabile triazene group (Ph-N=N-NR 2 ) as well as photocrosslinkable units based on substituted cinnamylidene malonyl moieties are reported. The polyesters were obtained by reacting a triazene containing difunctional alcohol with different substituted cinnamylidene malonic acid dichlorides. Irradiation at A > 395 nm enables selective photocrosslinking of the cinnamylidene malonyl ester units via [2 + 2] π-cycloaddition without affecting the triazene units. The photocrosslinking reaction of the triazene containing polyesters as well as triazene-free reference polyesters were investigated by UV and IR spectroscopy. After selective photocrosslinking the irradiated polymers became insoluble and no longer exhibited a T g below decomposition temperature. The crosslinked triazene containing polyesters show strong absorption at A = 308 nm and are therefore interesting candidates for applications using XeCl excimer laser ablation.