Benzoxazine-Based Thermosets with Autonomous Self-Healing Ability

Combining benzoxazine and ketene chemistries for self-healing of high performance thermoset surfaces

The use of oxoketene chemistry for self-healable polybenzoxazines is described.

A readily self-healing and recyclable silicone elastomer via boron–nitrogen noncovalent crosslinking

A self-healing silicone elastomer was synthesized via a one-pot and noncatalytic aza-Michael reaction because boron–nitrogen coordination bonds form reversible crosslinking points.

Synthesis of a Bisbenzylideneacetone-Containing Benzoxazine and Its Photo- and Thermally Cured Thermoset

A bis(4-hydroxybenzylidene)acetone/aniline-based benzoxazine (BHBA-a) was prepared from a bisbenzylidene-containing bisphenol, bis(4-hydroxybenzylidene)acetone (BHBA), aniline, and paraformaldehyde through Mannich condensation in a cosolvent of toluene/ethanol (2:1, v/v). The structure of BHBA-a was successfully confirmed by Fourier transform infrared and ¹H and ¹³C NMR spectra. According to the differential scanning calorimetry (DSC) thermogram of BHBA, an immediate exothermic peak after the melting peak was observed, suggesting that BHBA is thermally active. NMR data of thermally treated BHBA confirm that the immediate exothermic peak after melting of BHBA in the DSC thermogram is resulted from the curing of a double bond. UV and ¹H NMR spectra of BHBA-a show that the bisbenzylideneacetone moiety underwent dimerization through the [2π + 2π] cycloaddition. Therefore, two procedures were applied to cure BHBA-a. The first one was thermal curing of the double bond of bisbenzylideneacetone and oxazine moieties. The second one was photocuring of the bisbenzylideneacetone moiety, followed by thermal curing of the oxazine moiety. The thermal properties of thermosets were evaluated based on these two procedures. Thermosets of BHBA-a exhibit T _g as high as 318 °C for curing procedure 1 and 342 °C for curing procedure 2. These values are much higher than that of a traditional bisphenol/aniline-based benzoxazine thermoset. We conclude that the thermal curing of the double bond of bisbenzylideneacetone and photodimerization of bisbenzylideneacetone contributes to the good thermal properties.

Recycling and Self-Healing of Polybenzoxazines with Dynamic Sulfide Linkages

In this work, a recycling and self-healing strategy for polybenzoxazines through both S-S bond cleavage-reformation reaction and supramolecular attractions is described. Both recyclable and self-healable polybenzoxazines can be prepared from low cost chemicals with a simple procedure in only 30 minutes. For this purpose, inverse vulcanization of poly(propylene oxide)benzoxazine (PPOB) and diallybenzoxazine (B-al) with elemental sulfur was performed at 185 °C. The obtained cross-linked polymer films exhibited thermally driven recycling ability up to 5 cycles. Moreover, the self-healing ability of a test specimen was shown. Spectral characterizations, thermal stability and fracture toughness of the films were investigated after each recycling.

Photo-sensitive benzoxazine II: chalcone-containing benzoxazine and its photo and thermal-cured thermoset

Chalcone-containing benzoxazine (BHP-a) was synthesized. Two procedures were applied to cure BHP-a, thermal curing of chalcone and oxazine moieties. Another one was photo curing the chalcone moiety, followed by thermal curing of the oxazine moiety.

Copolymerization and phase separation behaviors of benzoxazine–amine thermosets

A benzoxazine/amine mixture exhibits phase separation in its cured resin through competitive copolymerization paths.

An aggregation-induced emission enhancement fluorescent benzoxazine-derived macromolecule: catalyst-free synthesis and its preliminary application for the determination of aqueous picric acid

An aggregation-induced emission enhancement macromolecular benzoxazine derivative was synthesized by a catalyst-free Mannich reaction and showed a fluorescence quenching response towards nitro compounds.

Thermally self-healing silicone-based networks with potential application in recycling adhesives

A simpler approach is developed to obtain recyclable self-healing polysiloxane networks based on the thiol-ene reaction and Diels–Alder (DA) reaction which found potential applications in recyclable adhesives especially for glass bonding.

Corrosion protection of hydrophobic bisphenol A-based polybenzoxazine coatings on mild steel

Hydrophobic bisphenol A-based polybenzoxazine coatings with excellent corrosion resistance were prepared through a simple dip coating and thermal curing method.

Multivalent photo-crosslinkable coumarin-containing polybenzoxazines exhibiting enhanced thermal and hydrophobic surface properties

Mono-, bi-, and trivalent coumarin-containing benzoxazine monomers were synthesized by facile Mannich reactions of 4-methyl-7-hydroxycoumarin and paraformaldehyde with aniline, bisphenol A–NH₂, and 1,3,5-tri(4-aminobenzene).

Self-healing elastomer assembly towards three-dimensional shape memory devices

The superior self-healing elastomers were readily prepared by free-radical copolymerization of methoxyethyl acrylate (MEA) and N,N-dimethylacrylamide (DMAA).

Vinyl benzoxazine: a novel heterobifunctional monomer that can undergo both free radical polymerization and cationic ring-opening polymerization

A novel heterobifunctional monomer (6-ethenyl-3-phenyl-3,4-dihydro-2H-1,3-benzoxazine (VBOZO)) containing both a vinyl group and benzoxazine group was successfully prepared and the homo- and copolymerization reactions of this monomer were studied.

Cardanol benzoxazines – interplay of oxazine functionality (mono to tetra) and properties

Cardanol, an agrowaste – solventless synthesis and processability of benzoxazine monomers. Tailoring the polymer properties as a function of oxazine functionality in the monomers.