Preparation and characterization of an acrylated‐coumarin‐containing photo‐crosslinked thiol‐ene network: Investigation of the free‐volume, thermal, UV, and photoluminescence properties

Abstract Coumarin, a versatile compound, has attracted great interest in polymer science due to its unique properties and diverse applications. The use of coumarins in polymer research opens avenues for the development of materials with improved functionalities. In this study, an acrylated coumarin (a‐coumarin) compound‐containing polymeric films was obtained via UV curing through a thiol‐ene click reaction with a free radical mechanism. The obtained a‐coumarin‐containing polymeric films were subjected to functional characterization using FTIR and NMR analyses and thermal characterization via DSC and TGA. UV–vis and PL analyses were performed to determine the optical properties. Using positron annihilation lifetime spectroscopy (PALS), the free volume and proportional free volume fraction of the films were analyzed both below and above the glass transition temperature ( T g ). The T g values obtained from PALS were several degrees lower than those obtained via DSC. A‐coumarin additives inhibit segmental mobility, hence reducing the proportional free volume fraction and increasing the T g . This study is the first in the literature to investigate the free volume properties of coumarin‐containing polymeric films. The study reveals the impact of a‐coumarin on thermal, optical, and free volume properties, paving the way for the design of advanced functional materials. Highlights A‐coumarin films were made via UV curing and thiol‐ene click chemistry. PALS analyzed free volume below and above the glass transition temperature. A‐coumarin reduced free volume, increasing T g and stabilizing polymer films.