Synthesis and characterization of poly(benzoxazine-co-siloxane) oligomers end-capped with arylacetylene

Four poly(benzoxazine-co-siloxane) oligomers (PBcSs) were successfully synthesized by improving the synthesis step and controlling the ratio of phenol, bisphenol A, 1,3-bis(3-aminopropyl)tetramethyldisiloxane, m-aminophenyl acetylene, and formaldehyde; the resulting compounds all exhibited good processing properties. Siloxane addition can significantly improve the toughness of the polybenzoxazines. Additionally, compared with the PBcSs containing only phenol structure, the introduction of bisphenol A has a decelerating effect on the polymerization process of the benzoxazine oligomer, which leads to an increase in the exothermic peak temperature. Simultaneously, the PBcS containing bisphenol A also exhibits a higher glass transition temperature and increased thermal stability, but reduced flexural strength. Conversely, compared to the benzoxazine oligomers that do not contain alkynyl groups, the introduction of the terminal alkynyl group can accelerate the polymerization process, decrease the exothermic peak temperature, significantly increase the glass transition temperature, and greatly improve the heat resistance; the 5% thermal decomposition temperature of cured product is increased by up to 101[degrees]C. Furthermore, under conditions that ensure high flexural strength, appropriate alkynyl content can also significantly increase the material's flexural modulus. KEYWORDS heat resistance, oligomers, polybenzoxazine, siloxane, terminal alkynyl groups
1 | INTRODUCTION Polybenzoxazines have attracted considerable attention as important thermosetting resins owing to their outstanding properties, including flexible molecular design, good dielectric properties, a long shelf life, and no [...]