Synthesis and Properties of Cationic Photocurable Polymethylsiloxane/Eugenol-Modified Oxetane Monomers

Herein, we report three cationic photocurable polymethylsiloxane/eugenol-modified oxetane monomers (Eugenol-Sin, n = 3, 6, 9). Eugenol-Sin monomers can polymerize well in the presence of a photoinitiator under irradiation and promote the opening ring reaction of the ternary oxygen heterocycle monomer (E4221). The final conversions of oxirane and oxetane groups for E/Eugenol-Sin composed of E4221 and Eugenol-Sin are 73.3% and about 74.0% respectively, which were higher than those of nopol-based monomers previously reported by us. The rigid benzene ring of eugenol and the soft thermostable hydrophobic polymethylsiloxane chain can endow UV-cured films with good hydrophobicity, heat resistance, and tensile properties. Thus, the water contact angles of E/Eugenol-Sin reach up to 94.2°. Moreover, the lengthening of the polymethylsiloxane chain length can enhance not only the heat resistance but also the tensile performance of E/Eugenol-Sin but reduce glass transition temperature (Tg). Furthermore, when the added amount of Eugenol-Sin increases, the heat resistance and tensile performance of E/Eugenol-Si9 rise first and subsequently decline, but the glass transition temperature shows a trend of continuous decrease. Besides, compared with nopol-based monomers, Eugenol-Sin exhibit a much better thermostability. Eugenol-Sin demonstrate a great practical application perspective owing to advantages in terms of cost and performances.