Synthesis of polybenzoxazine precursors using thiols: Simultaneous thiol–ene and ring‐opening reactions

Abstract

A new class of polybenzoxazine precursors of combined molecular structure of benzoxazine in the open and ring form has been developed. Thermally curable benzoxazine networks were obtained by simultaneous photoinduced thiol‐ene and Catalytic Opening of the Lateral Benzoxazine Rings by Thiols (COLBERT). The thiol‐ene reactions were initiated by photolysis of a free radical photoinitiator, 2, 2‐dimethoxy‐2‐phenyl acetophenone (DMPA), and the competing COLBERT reaction was triggered by thiol compound, 1,2‐ethanedithiol, present in the reaction mixture. The extent of reactions was evaluated by conducting experiments both under UV irradiation and in dark using model benzoxazines. The precursor soft films (pre‐P(B‐ala‐DTE)) were prepared by irradiating solutions of diallyl functional benzoxazine (B‐ala), 1,2‐ethanedithiol and DMPA. The obtained pre‐P(B‐ala‐DTE) films were then cured through thermally activated ring opening reaction of remaining benzoxazine groups yielding a more rigid and tough film. Thermal and mechanical properties of the films were investigated by DSC, DMA and TGA and compared with a typical polybenzoxazine, P(B‐ala). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Thiol reactive polybenzoxazine precursors: A novel route to functional polymers by thiol-oxazine chemistry

“…In particular, COLBERT allows benzoxazine to polymerize even under ambient temperature. In our laboratory, we have utilized this reaction and demonstrated that cross-linked but additionally curable soft benzoxazine films can be prepared by simultaneous COLBERT and photoinduced thiol-ene reactions using difunctional thiol and diallyl functional benzoxazine [40]. Moreover, we have showed that benzoxazines can be used as a linker between two different polymers forming a block copolymer and COLBERT acted as a kind of thiol-oxazine click reaction to do so [41].…”

Synthesis and properties of organo-gels by thiol-benzoxazine chemistry

“…Crosslinked but additionally curable soft benzoxazine films were prepared by simultaneous photoinduced thiol-ene and COLBERT reactions using difunctional thiol and diallybenzoxazine. [38] Similar approach was also used to form dual-cure hybrid polymer networks. [39] In a recent report from the authors' laboratory, it was demonstrated that benzoxazines can be used as a linker between two different polymers to form a block copolymer by using COLBERT as a ligation process in a manner of Thiol-X chemistry.…”

Polybenzoxazine: A Powerful Tool for Removal of Mercury Salts from Water

“…[15] These materials offer low water absorption, high char yield, resistance against flame, high modulus, high strength, high glass transition temperatures, chemical resistance, long shelf life and very limited volumetric change upon curing. [15a, 16] The synthesis of these materials is performed by non-catalytic thermally activated ring opening of the corresponding benzoxazine monomers (Scheme 1).…”