Synthesis of benzoxazine
Macromolecules42 7 Primary amine-functional benzoxazine monomers and their use for amide-containing monomeric benzoxazines.
From other bio-phenols Many other bio-phenols can be used for the design of benzoxazine monomers. This is likely due to the poorer purity of the para species and show lower exotherm maximum temperature than the pure sample as shown in the lack of melting endotherm in the para species. The Journal of Organic Chemistry78 13 End-chain functionalization polymers Beyond the elaboration of symmetric and asymmetric benzoxazine monomers, a recent challenge is to add benzoxazine functionalities to polymers, benefiting then from the versatile design of Bz monomers.
However, only around Macromolecules51 19 In consequence, for the last 5 years, the number of studies related to bio-based benzoxazines is exploding as a consequence of the versatility of the design of the chemical structure of their monomers [ 16 ].
Cardanol, a bio-phenol bearing a C15 alkyl chain in meta position able to provide better processability and flexibility to the material through internal plasticization is relevant for the synthesis of usually brittle Bz materials. This scheme highlights the great versatility in the design of benzoxazine monomers, gathered in different classes depending on their functionality. However, the low cross-linking density and Tg of the corresponding PBz materials, as well as the high polymerization temperatures, are drawbacks for the elaboration of high-performance thermosets and emphasize the use of cardanol-based di-Bz as processing aid i. This polybenzoxazine derived from ortho-functional benzoxazine monomer is a subject of very recent paper where unexpected superior properties were observed for ortho-functional benzoxazine in comparison of para-functional benzoxazine Liu and Ishida, Introduction Traditional thermosets resins are well known for their high-performance properties [ 1 ]. Tarek Agag, Carlos R. However, it was very difficult to measure mechanical properties since they were brittle. In this study, a main-chain type ortho-functional polybenzoxazine with amide—imide and benzoxazine groups as repeating units in the main-chain oAI-ddm has also been prepared. Nevertheless, most of the Bz monomers synthesized from bio-based phenolic compounds are suffering from several disadvantages, either for the synthesis of the Bz monomer, or the elaboration or the properties of the final materials. More importantly, the low reactivity of cardanol offers the possibility to control the synthesis of a mono-cardanol Bz with a free primary amine moiety that can be further coupled with another bio-based phenol like vanillin.
based on 87 review