Synthesis and thermomechanical properties of hybrid photopolymer films based on the thiol-siloxane and acrylate oligomers

The synthesis of hybrid oligomers for photopolymer compositions was carried out based on the thiol-ene reaction between the tetraacrylate dihydroxydiphenylsulfide derivative and thiol-siloxane oligomer. Thiol-siloxane oligomer was synthesized by condensation of diphenylsilanediol and 3-(mercaptopropyl)-trimethoxysilane. The thiol-siloxane oligomer structure was identified by 1H, 13C, 29Si NMR spectroscopy including COSY, HSQC, and HMBC methods and by MALDI-TOF mass spectrometry. The hybrid oligomers were obtained at different tetraacrylate:thiol-siloxane oligomer ratios (1:2, 1:1, 2:1). The obtained compositions are resistant to the oxygen inhibition of photopolymerization and give flexible, thermostable, and rigid polymer films under UV light at air atmosphere. The degree of the film photopolymerization was monitored by IR spectroscopy. The thermomechanical properties of photopolymer films were determined using thermogravimetric, differential scanning calorimetric, and dynamic mechanical analyses. The storage modulus (E′) at room temperature (1.16–1.88 GPa) and the glass transition temperatures (78–133 °C) were determined for photopolymer films obtained at different ratios of acrylate and thiol-siloxane units. The photocured hybrid films exhibit high stability to thermal decomposition in the inert (T 10% over 321 °C) and oxidizing (T 10% over 314 °C) atmospheres.