Renewable benzoxazine monomers from “lignin-like” naturally occurring phenolic derivatives

Abstract

The benzoxazines of three naturally occurring phenylpropanoid phenols: ferulic, coumaric, and phloretic acids, and their esters are described. Benzoxazines with conjugated unsaturated chains exhibit unusual poor thermal stability and degrade partially at the polymerization temperature making necessary the use of a catalyst (BF 3 .Et 2 O) to low the polymerization temperature and prevent degradation. Polybenzoxazines are prepared thermally and characterized by DSC and TGA techniques.The resulting materials have superior Tgs when compared with those prepared from an unsubstituted monofuctional benzoxazine due to the additional crosslinking through the ester and carboxylic moieties. V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 00, 000-000 KEYWORDS: cationic polymerization; crosslinking; polybenzoxazines; renewable resources; thermal properties; thermosets INTRODUCTION Polybenzoxazines are a relatively new class of phenolic type thermosets developed to overcome most of the short-comings associated with the traditional phenolic resins. During the last decade, polybenzoxazines have attracted significant attention of both industry and research community because of their unique advantages over most of the known polymers, 1 becoming one of a rare few new polymers commercialized in the past 30 years.

Tailor-made and chemically designed synthesis of coumarin-containing benzoxazines and their reactivity study toward their thermosets

“…However, another reason for the higher T g of poly(MU‐a) compared to that of poly(U‐a) might be due to the presence of the methyl group in the repeating units, which increases the steric constraints toward molecular rearrangement and consequently impairing chain mobility resulting in a higher value of T g . Poly(PH‐a) shows the lowest value of the T g obtained in this study and is consistent with results previously reported in the literature . It has been documented that a higher cross‐linking in methyl cinnamate‐containing resins, with respect to the unsubstituted PH‐a , is due to additional cross‐linking sites, such as the extra CC double bond, as well as more possible cross‐linking reactions as the reported transesterification between ester groups and the –OH generated during polymerization of the benzoxazines …”

“…Poly(PH‐a) shows the lowest value of the T g obtained in this study and is consistent with results previously reported in the literature . It has been documented that a higher cross‐linking in methyl cinnamate‐containing resins, with respect to the unsubstituted PH‐a , is due to additional cross‐linking sites, such as the extra CC double bond, as well as more possible cross‐linking reactions as the reported transesterification between ester groups and the –OH generated during polymerization of the benzoxazines …”

“…As known, the synthesis of benzoxazines involves phenolic compounds. They are usually derived from the petrochemistry but could easily be replaced by other biomass‐based phenolic compounds . The feasibility of using biomass renewable resources as raw materials for the synthesis of benzoxazine resins has been reported by not only substituting the phenolic moiety but also the amine portion of the resins.…”

High‐Performance Bio‐Based Benzoxazines from Enzymatic Synthesis of Diphenols

“…As aromatic compounds including phenolic derivates are the second most abundant class of organic compounds in nature representing about 25% of the earth's biomass, quite a large number of renewable phenol derivatives have been tested in recent years to synthesize benzoxazine precursors such as diphenolic acid, cardanol, vanillin, eugenol, chavicol, guaiacol, “lignin‐like” naturally occurring phenolic compounds (coumaric acid, ferulic acid, and phloretic acid), umbelliferone, arbutin, urushiol, catechol, etc. A special interest is focused on difunctional benzoxazine structure because it leads to cross‐linking.…”

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

“…Another important feature of polybenzoxazines is the simple synthesis of their monomers. Basically, any suitable primary amine and phenolic compound could form 1,3-benzoxazine monomers with formaldehyde (Scheme 1) [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. The only possible drawback in monomer synthesis is the selection of functional groups on starting materials and solvent systems that suppress the reaction.…”