The Charge Transfer Complex Formed between the Components of Photopolymer Material as an Internal Sensitizer of Spectral Sensitivity

Abstract A photosensitive charge transfer complex (CTC) is formed between the components of the photopolymer material: the tetra–acrylate monomer synthesized from dihydroxydiphenyl sulfide (TADDS) and a photoinitiator, a cationic sulfonium salt synthesized from diethylthioxanthen‐9‐one (SSDETX). It allows one to perform laser recording of the microstructures in the hybrid photopolymer material using absorption of CTC at λ=473 nm. The 1 : 1 molecular composition of CTC was confirmed by applying the Job's method of continuous variation to determine the stoichiometry. The association constant (K AS(278°K) =17 L mol −1 ) was calculated using the modified Benesi‐Hildebrand equation. The thermodynamic parameters, such as enthalpy (ΔH=−15.63 kJ mol), entropy (ΔS°=−32.6 J mol −1 K −1 ), and the Gibbs free energy (ΔG=−6.63 kJ mol −1 ) were calculated using the Van't Hoff equation. These results indicate that CTC formation is an exothermic reaction. The experimental findings were supplemented by density functional theory (DFT) study of CTCs at the UB3LYP/6‐311G level as implemented in the Gaussian 09 software package. Charge transfer excitations were simulated by means of the time‐dependent density functional theory (TDDFT) approach. The DFT‐calculated spectra agree with the experimental data of spectral and photochemical properties of the [SSDETX‐TADDS] CTC.