Synthesis and photochemical properties of poly(1-(4-carboethoxyphenyl)-2-propen-1-one)

Abstract

New light-sensitive polymer, poly(1-(4-carboethoxyphenyl)-2-propen-1-one), $\text{M}{}_{\mathrm{w}}\text{= 1·3 × 10}{}^6$ Dalton, $\text{M}{}_{\mathrm{w}}\text{M}{}_{\mathrm{n}}\text{= 2·6}$, was prepared. On the basis of fractions prepared by photolysis, Mark-Houwink coefficients (α=0·79 ± 0·02 and K=(2·41 ± 1·4) × 10⁻³) were determined in chlorobenzene at 25°C employing low-angle laser light scattering and automatic viscometry. Quantum yield of main chain scissions (The Norrish Type II Reaction) was 0·45 in benzene solution under 366 nm radiation at room temperature. The Stern-Volmer constant for quenching of photolysis by naphthalene in benzene was 171 mol⁻¹ and 63 mol⁻¹ by 2,5-dimethyl-2,4-hexadiene in chloroform. The OO band of phosphorescence (438 nm) of the polyketone prepared was bathochromically shifted in comparison with poly(1-phenyl-2-propen-1-one), λ_max• = 409 nm. The transient spectrum measured by laser flash photolysis exhibited a maximum at 350 nm with a lifetime of 150 ns. The bimolecular quenching rate constant (k_q) for 2,5-dimethyl-2,4-hexadiene in chloroform was 5·57 × 10⁸ dm³ mol⁻¹ s⁻¹. This value agrees well with k_q = 4·2 × 10⁸ dm³ mol⁻¹ s⁻¹. based on the Stern-Volmer constant of photolysis quenching and lifetime estimated by laser flash photolysis.