Diphenolic acid (DPA) is a renewable chemical attracting great interest in biobased polymer science. Despite their low toxicity and high recyclability, the undesirable decarboxylation of DPA-based polymers generally leads to poor thermal stability and material failure restricting their practical applications. Here, we demonstrate that the incorporation of amide groups into a benzoxazine molecule can effectively avoid this problem while improving the thermally mechanical performance of the polybenzoxazine resin. We first synthesized a tetra-phenolic compound via a condensation reaction of DPA with hexanediamine through an ammonium salt route and then prepared a tetrafunctional benzoxazine, denominating as DHDA-fa, by a further reaction with furfurylamine and formaldehyde in a polyethylene glycol 200 (PEG-200) medium. The glass transition temperature (T g ) and decomposition temperature (T d5 ) of the resulting poly(DHDA-fa) were found to be 326 and 384 °C by DMA and TGA, respectively, which outperformed many biobased benzoxazine resins previously reported. Experimental results revealed that the enhanced hydrogen bonding and doubled oxazine functionary are the important contributors for the improved thermal and mechanical performances. This work confirmed a novel way to perfect DPA-based benzoxazine resins resulting in an effective strategy for developing biobased materials with high performance for practical applications.

Polybenzoxazines have a variety of advantages over most polymers, but the brittle feature limits the range of their applications. The most effective way for benzoxazine toughing is to copolymerize them with a well-designed benzoxazine monomer able to contribute self-plasticizing action. Here, a new bio-based benzoxazine was synthesized from diphenolic acid (DPA), the sustainable candidate of bisphenol A. By introducing three aliphatic chains into DPA, the special benzoxazine able to provide remarkable toughness effect is obtained. For the synthesis, DPA is amidated using lauryl amine to diphenolic lauramide (DLA) first, then convert to a benzoxazine (DLA-la) by Mannich-like reaction with lauryl amine and paraformaldehyde. A commercial benzoxazine, bis (4-(2H-benzo[e][1,3]oxazin-3(4H)-yl)phenyl)methane (PH-ddm), is employed as the toughing object to test the possibility of using DLA-la would offer a significant toughing effect. Experimental results show that DLA-la/PH-ddm blending would result in a perfect resin without phase separation, which exhibits an improved elongation at break higher by 70.5% than the bulk PH-ddm resin, while keeps tensile strength at 44.69 MPa. As the proposed toughing principle could be applied to a variety of commercially available benzoxazines, this research broadly contributes toward the development of benzoxazine industries.

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The development of bio-based phenols to replace bisphenol A (BPA) is an ongoing challenge in polymer industry. In this work, we recommend a renewable bisphenol, bisguaiacol amide (BGA), which is...

Styrene has been widely used as a reactive diluent for a variety of commercial unsaturated polyester resins (UPRs), but suffered from high volatility. In this work, we developed a bio-based reactive diluent, 4-vinylguaiacol glycidyl ether (DE4VG), via an epoxidation of 4-vinylguaiacol (4VG). Excellent miscibility and high reactivity of DE4VG were demonstrated by a series of copolymerization tests with an unsaturated polyester prepolymer (named PMSD) synthesized from maleic anhydride, 1,3-dihydroxypropane and succinic acid. While, significant advantages in terms of viscosity and volatility were confirmed. Additionally, DE4VG provides both vinyl and epoxide groups and the epoxide groups were cured using 4,4-diamino diphenylmethane (DDM) to participate the network formation of the cured PMSD/DE4VG/TBPB/DDM resin, result-