The high curing temperature of benzoxazines is an important concern for production materials under benign conditions via autoclave curing, which limits industrial applications of these resins as high-performance polymers. Thioamide as a catalyst to lower the ring-opening polymerization (ROP) temperature of simple 1,3-benzoxazines was synthesized from renewable compounds such as furfural and furfurylamine by using the Willgerodt–Kindler reaction. Differential scanning calorimetry studies revealed that the observed reducing effect is more pronounced for onset curing temperatures and as much as 48 °C reduction is noted. Moreover, the catalytic performance of the thioamide could be enhanced by mixing with Cu­(II) benzoate. The latent character of the catalyst system was confirmed by NMR and Fourier transform infrared spectroscopy. Moreover, thermal stabilities of the catalyzed polybenzoxazines were analyzed and compared to uncatalyzed polybenzoxazines, and an apparent char yield increment was observed for all the catalyzed samples.

Photochemical techniques have recently been revitalized as they can readily be adapted to different polymerization modes to yield a wide range of complex macromolecular structures. However, the implementation of the photoinduced cationic methods in the polymerization of cyclic siloxane monomers has scarcely been investigated. Octamethylcyclotetrasiloxane (D4) is an important monomer for the synthesis of polydimethylsiloxane (PDMS) and its copolymers. In this study, the cationic ring-opening polymerization (ROP) of D4, initiated by diphenyl iodonium hexafluorophosphate (DPI), has been studied. Both direct and indirect initiating systems acting at broad wavelength using benzophenone and pyrene were investigated. In both systems, photochemically generated protonic acids and silylium cations are responsible for the polymerization. The kinetics of the polymerization are followed by viscosimetry and GPC analyses. The reported approach may overcome the problems associated with conventional methods and therefore represents industrial importance for the fabrication of polysiloxanes.