Preparation and properties of UV-curable silicone materials bridged by trifluoropropyl(methyl)siloxyl groups

Hexamethylcyclotrisiloxane was polymerized by non-equilibrium anion living polymerization initiated by lithium dimethylsilanol, and bridged with methyltrifluoropropyldichlorosilane to prepare methyltrifluoropropylsiloxy-bridged α, ω-dimethylsiloxy-terminated polydimethylsiloxane (DTFP), and then methyltrifluoropropylsiloxy-bridged α, ω-dimethylacryloxybutylsiloxy-terminated polydimethylsiloxane (DAFP) was prepared through hydroxyl protection, hydrosilylation, deprotection of trimethylsiloxyl groups and condensation reaction with acrylic acid. DAFP was mixed with α , ω -bis[dimethyl-[3-[2,2-bis(acryloyloxy)butoxy]propyl]silyl]-terminated PDMS oligomer (DBABP), a crosslinking density modifier, at a mass ratio of 70: 30, and then 2 parts of a photoinitiator consisting of 2-hydroxy-2-methyl-1-phenyl-1-propanone and diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide blended at a mass ratio of 1: 1 were added, and a cured film was prepared under UV light irradiation. The effects of initiator composition, UV irradiation time, and molecular weight of DAFP oligomers on the gelation yield, water absorption, water contact angle, thermal stability, and dielectric properties of the UV-cured products were investigated. These findings are significant as they contribute to the understanding of the synthesis and characteristics of new materials in the field of materials science and polymer chemistry. DAFP oligomers can be copolymerized with the DBABP oligomer within 25 s of UV irradiation. The sample (DAFP-2) with the best performance has a gelation yield of about 87 %, its T5% in nitrogen can reach 377.7 °C, its water absorption rate is as low as 0.85 %, and its surface water contact angle can reach 116°. Under 2 GHz conditions, the dielectric constant of the UV-cured PDMS film containing 2.61 % F element is 2.71, which is 9.1 % lower than that of the pure PDMS. Meanwhile, its dielectric loss is also significantly reduced.