Preparation and properties of novel benzoxazine and polybenzoxazine with maleimide groups

Fast-Curing of Liquid Crystal Thermosets Enabled by End-Groups Regulation and In Situ Monitoring by Triboelectric Spectroscopy

The development of high-performance polymer is crucial for the fabrication of triboelectric nanogenerators (TENGs) used in extreme conditions. Liquid crystal polyarylate thermosets (LCTs) demonstrate great potential as triboelectric material by virtue of exceptional comprehensive properties. However, there are only a few specific end-groups like phenylethynyl matching the LCT polycondensation temperature (above 300 °C). Moreover, the excellent properties of LCTs rely on the crosslinked network formed with long curing time at high temperature, restricting their further application in triboelectric material. Herein, a fast-curing LCT is designed by terminating with 4-maleimidophenol possessing appropriate reactivity. The resultant LCT (MA-LC-MA) exhibits much lower polycondensation temperature (250-270 °C) and curing temperature of 300 °C within only 1 min compared to typical LCTs (cured at 370 °C for 1 h). Furthermore, the cured MA-LC-MA retains a high glass transition temperature of 135 °C, storage modulus of 6 MPa even at 350 °C, and great electrical output performance. Additionally, triboelectric measurement related to the dielectric properties that vary with crosslinked network is innovatively utilized as an analysis technique of curing progress. This work provides a new strategy to design high-performance TENGs and promotes the development of next generation thermosets in extreme conditions.

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers

Due to their outstanding and versatile properties, polybenzoxazines have quickly occupied a great niche of applications. Developing the ability to polymerize benzoxazine resin at lower temperatures than the current capability is essential in taking advantage of these exceptional properties and remains to be most challenging subject in the field. The current review is classified into several parts to achieve this goal. In this review, fundamentals on the synthesis and evolution of structure, which led to classification of PBz in different generations, are discussed. Classifications of PBzs are defined depending on building block as well as how structure is evolved and property obtained. Progress on the utility of biobased feedstocks from various bio-/waste-mass is also discussed and compared, wherever possible. The second part of review discusses the probable polymerization mechanism proposed for the ring-opening reactions. This is complementary to the third section, where the effect of catalysts/initiators has on triggering polymerization at low temperature is discussed extensively. The role of additional functionalities in influencing the temperature of polymerization is also discussed. There has been a shift in paradigm beyond the lowering of ring-opening polymerization (ROP) temperature and other areas of interest, such as adaptation of molecular functionality with simultaneous improvement of properties.

Synthesis and properties of a benzoxazine monomer containing maleimide and biphenyl groups

Benzoxazine resin exhibits excellent properties and is widely used in many fields. Herein, the synthesis of a novel compound, the bis(2,4-dihydro-2 H-3-(4- N-maleimido)phenyl-1,3-benzoxazinyl)biphenyl (BMIPBB), has been reported, which was synthesized by reacting N-(4-aminophenyl)maleimide (APMI), formaldehyde, and 4,4’-dihydroxybiphenyl. 1,3,5-three(4-(maleimido)phenyl)-1,3,5-triazine (TMIPT) was formed as an intermediate during the reaction. The proton nuclear magnetic resonance (1H-NMR) and Fourier transform-infrared (FTIR) spectroscopy experiments were conducted to determine the structure of BMIPBB. BMIPBB was obtained as a reddish-brown solid in 40.1% yield. The thermal properties of BMIPBB were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Analysis of the DSC curves revealed that the broad peak representing the release of curing reaction heat appeared in the temperature range of 140–330°C. The peak temperature was 242.59°C and the heat of the reaction was 393.82 J/g, indicating that the rate of the curing reaction was low and the heat of the reaction was high. Analysis of the TGA results revealed that the weight loss rate was 5% at 110°C. The monomer exhibited a significant weight loss in the range of 320–500°C. The compound lost 50% of its weight at a temperature of 427°C.

Advanced development of dairy farm waste-based biocarbon-reinforced unsymmetrical structured bio-phenolic polybenzoxazine composites

In the present work, an attempt has been made to develop cow manure carbon-reinforced hybrid biophenol-based benzoxazine composites for antifouling coating applications. Bio-based benzoxazine with unsymmetrical molecular structure was synthesized using the mixture of a combination of cardanol and eugenol with diaminodiphenyl methane and paraformaldehyde, and the hybrid-benzoxazine obtained was characterized using different analytical techniques, viz., Fourier transform infrared, nuclear magnetic resonance and MALDI mass. Bio-based benzoxazine was further reinforced with varying weight percentages (1, 3 and 5 wt%) of biocarbon derived from cow manure to obtain hybrid composite coatings. The hybrid benzoxazine matrix and composites were studied for their thermal behaviour, contact angle (CA), morphology, corrosion-resistant behaviour and antifouling character to utilize them as coatings materials for different industrial applications. Results obtained from different studies inferred that the biocarbon-reinforced composites possess an enhanced value of glass transition temperature (249°C), high char yield (38.4%), improved CA (105.6°), higher efficiency of corrosion protection against mild steel surface (98%) and improved antimicrobial activity.

Cyclo-oligomerization of hydroxyl-containing mono-functional benzoxazines: a mechanism for oligomer formation

The oligomerization of mono-functional benzoxazines is demonstrated with intermolecular cyclization via a Mannich bridge structure as the primary reaction pathway.

Coumarines as masked phenols for amide functional benzoxazines

Benzoxazines with amide linkages were successfully prepared from 3,4-dihydrocoumarine using either one-pot or stepwise pathways.

Novel glass fabric-reinforced polybenzoxazine–silicate composites with polyvinyl butyral for high service temperature applications

The aim of this study is to develop novel glass fabric-reinforced polybenzoxazine–silicate composites with enhanced performances, which can overcome the disadvantages related to the low crosslink density of glass fabric-reinforced polybenzoxazine composites.

Functionalized MWCNTs, an efficient reinforcement for the preparation of eugenol based high performance PBz/BMI/CNT nanocomposites exhibiting outstanding thermo-mechanical properties

This work contemplates the stabilization of eugenol-based benzoxazine networks with the addition of BMI and amine functionalized multiwalled carbon nanotubes.

Study on thermal degradation mechanism of a cured aldehyde-functional benzoxazine

Thermal degradation mechanism of a cured aldehyde-functional benzoxazine.

Thermal, mechanical and antibacterial properties of cyclophosphazene incorporated benzoxazine blended bismaleimide composites

Cyclophosphazene is incorporated in to Bz–Bmi composites in order to improve the thermal, mechanical, electrical resistance and antibacterial properties of CP–Bz–Bmi composite.

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.

Novel E glass composites with polybenzoxazine and in situ generating reactive multi branched titanate for low temperature cure and high thermal resistance applications

Novel E glass composites with polybenzoxazine andin situgenerating reactive multi branched titanate for low temperature cure and high thermal resistance applications.

Supramolecular functionalized polybenzoxazines from azobenzene carboxylic acid/azobenzene pyridine complexes: synthesis, surface properties, and specific interactions

Supramolecular complex of azobenzene carboxylic acid/pyridine functionalized benzoxazine system featured significantly lower curing temperatures and maintain high water contact angles.

Reaction mechanism and synergistic anticorrosion property of reactive blends of maleimide-containing benzoxazine and amine-capped aniline trimer

Reaction mechanism and synergistic effect on anticorrosion for reactive blends of a maleimide-containing benzoxazine and aniline trimer have been explored.

Highly cross-linked thermosetting benzocyclobutene-modified bis-benzoxazine resins from 4-hydroxybenzocyclobutene

In the present study, benzocyclobutene (BCB) was incorporated into the benzoxazine (BOZ) monomers. BCB-functionalized BOZ monomers were synthesized by the reaction of 4-hydroxybenzocyclobutene, aromatic diamine, and paraformaldehyde in dioxane under reflux. The structure of the monomers was characterized by Fourier transform infrared spectroscopy (FTIR) and proton and carbon nuclear magnetic resonance spectroscopies. The monomers possess two kinds of ring-opening polymerizable functional groups, BCB and BOZ. Differential scanning calorimetry and FTIR were used to study the polymerization behavior of the monomers. Dynamic mechanical analysis demonstrates that the related polymers show high storage moduli maintained in a wide range of temperature up to 300°C and high glass transition temperature at about 330°C. The incorporation of BCB improved the thermal stability and mechanical property of the monomer.