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A novel polycyclic naphthoxazine resin (NSA‐thiq) is synthesized via N, O‐acetal forming reaction between o‐hydroxyl naphthaldehyde and 1,2,3,4‐tetrahydroisoquinoline. The chemical structure of the monomer is investigated and confirmed by 1H and 13C NMR, Fourier‐transform infrared (FT‐IR) spectroscopy, and high‐resolution mass spectrometry. Besides, the ring‐opening polymerization behavior similar to ordinary benzoxazine resins is observed by differential scanning calorimetry (DSC) and in situ FT‐IR analyses, leading to the formation of the phenolic cross‐linked network. Notably, DSC thermograms indicate that the newly obtained polycyclic naphthoxazine resin exhibits much lower polymerization temperatures compared to many other reported benzoxazine or naphthoxazine resins. Moreover, the corresponding polybenzoxazine (poly(NSA‐thiq)) shows comparable thermal stability in comparison with thermosets derived from monobenzoxazine resins. As a consequence of these unique performances, NSA‐thiq is applied as a property modifier for a commercialized benzoxazine resin (BA‐a). The glass transition temperature of copolymeric thermosets is enhanced without sacrificing too much thermal stability and heat resistance. Here, another series of naphthoxazine thermosetting resin is explored, which can provide more examples for constructing composites based on thermoset polymers. [ABSTRACT FROM AUTHOR]

Aromatic polyimides have attracted wide attentions in fields of aerospace, microelectronics and defense applications due to their outstanding thermal and mechanical performances. However, the rigidity originating from the imide structure attached with an aromatic ring causes difficulties in processing. In this study, we synthesized two ortho-phthalimide functional benzoxazine monomers with additional cross-linkable groups (including both furan and alkynyl). An ortho-phthalimide functional phenol, 2-(2-hydroxyphenyl) isoindole-1,3-dione (oPP), was obtained by reacting o-aminophenol and phthalic anhydride in acetic acid. Two monofunctional ortho-phthalimide containing benzoxazine monomers (oPP-fa and oPP-pa) were then synthesized using the Mannich reaction based on raw materials of oPP, furfurylamine/propargylamine and paraformaldehyde in toluene. The structures of benzoxazine monomers were confirmed by FT-IR and 1H NMR spectroscopies. We also investigated effects of cross-linkable functionalities on curing behaviors as well as their corresponding polymerization mechanisms. The activation energies of oPP-fa and oPP-pa were calculated by Kissinger and Ozawa equations based on DCS measurements with different heating rates. It demonstrates that the exothermic peak temperature of oPP-pa is located at 178.5 °C, which is much lower than that of oPP-fa (223.3 °C). The alkyne group in oPP-pa plays a catalytic effect role in reducing the ring-opening polymerization temperature of the oxazine ring. Moreover, the thermogravimetric analyzer (TGA) was used to evaluate thermal properties of the obtained polybenzoxazine thermosets. Both thermosets exhibited improved thermal stability compared with some other reported monobenzoxazine-derived polybenzoxazines. [ABSTRACT FROM AUTHOR]

Micro- and nano-scale carbon materials have been extensively investigated as additives in lubricants owing to their remarkable capability for friction reduction and enhancement of thermal conductivity within lubrication systems. Nevertheless, it is still highly desirable for oil-based lubricants to involve well-dispersed ultrafine carbonaceous particles without complicated chemical modification. Herein, we present a strategy to achieve 3D graphene additive in lubricants based on rapid laser irradiation. Notably, PAO4 containing 3D laser-induced graphene (LIG) additive exhibits excellent tribological properties in comparison with many other unmodified carbonaceous materials, including graphene, graphene oxide, single-wall nanotubes, and carbon black. In addition, the lubrication properties of PAO4 can be significantly improved by manipulating the concentration of the 3D LIG additive. With the addition of only 0.1 wt% 3D LIG-10, PAO4 lubricant system shows a reduction of 22% in coefficient of friction (COF) and a reduction of 95% in terms of wear coefficient compared to the base oil. In this work we provided a new strategy to produce 3D graphene oil additives for excellent tribological and wear performance. [Display omitted] • 3D porous graphene materials used as lubricant additives have been fabricated. • PAO4 with 3D LIG exhibits excellent tribological properties in comparison with common carbon additives. • PAO4 with 0.1 wt% 3D LIG shows reductions of 22% for COF and 95% of wear. [ABSTRACT FROM AUTHOR]