Ternary polybenzoxazine/POSS/SWCNT hybrid nanocomposites stabilized through supramolecular interactions

Tribological properties of bismaleimide reinforced with Si-containing benzoxazine monomer

To improve the mechanical and tribological properties of bismaleimide (BMI) resin, a novel Si-containing benzoxazine (Si-BOZ) monomer was synthesized using a solvent process and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane as a silane coupling agent. The novel Si-BOZ monomer was subsequently blended with BMI to prepare Si-BOZ/BMI polymer alloys. Furthermore, the effect of Si-BOZ content on the mechanical, tribological, and thermal properties of Si-BOZ/BMI alloys was investigated. The results revealed that the addition of Si-BOZ to BMI improved the mechanical properties and wear resistance of Si-BOZ/BMI; moreover, the glass transition temperature of cured Si-BOZ/BMI alloys was lower than that of pure BMI resin. These results confirmed that the increase in wear resistance of Si-BOZ/BMI alloys can be attributed to the increase in thermal resistance and improvement in mechanical performance owing to the addition of Si-BOZ.

Preparation of benzoxazine-modified halloysite nanotubes and its application on epoxy/benzoxazine composites

Benzoxazine monomer (named as B-aptes) was synthesized from 3-aminopropyltriethoxysilane (KH-550), bisphenol A (BPA), and paraformaldehyde. Subsequently, functionalized halloysite nanotubes were obtained by introducing B-aptes onto the surface of halloysite nanotubes (HNTs). Then, benzoxazine-modified halloysite nanotubes (B-HNTs) were used to combine with BPA epoxy resin to prepare the diglycidyl ether of bisphenol-A (DGEBA)/B-HNTs composites. The homogeneous dispersion state of modified HNTs in the cured composite matrix was observed by scanning electron microscopy. Differential scanning calorimetry was used to investigate polymerization behaviors of ternary composites. The results showed that the ternary composite possessed lower polymerization temperature compared with the neat DGEBA/benzoxazine. According to the results of thermogravimetric analysis, the thermal stability of DGEBA/benzoxazine copolymers was improved by the modified HNTs, the char yield increased with the increase of HNTs mass ratio. The results of mechanical tests and dynamic mechanical analysis displayed that the DGEBA/B-HNTs composites possessed promoted mechanical properties.

Triazine-functionalized covalent benzoxazine framework for direct synthesis of N-doped microporous carbon

A covalent benzoxazine framework was synthesized and underwent thermal curing, carbonization and KOH activation providing the nitrogen-doped microporous carbon.

Diphenylpyrenylamine-functionalized polypeptides: secondary structures, aggregation-induced emission, and carbon nanotube dispersibility

In this study we prepared-through ring-opening polymerization of γ-benzyl-l-glutamate N-carboxyanhydride (BLG-NCA) initiated by N,N-di(4-aminophenyl)-1-aminopyrene (pyrene-DPA-2NH2)-poly(γ-benzyl-l-glutamate) (PBLG) polymers with various degrees of polymerization (DP), each featuring a di(4-aminophenyl)pyrenylamine (DPA) luminophore on the main backbone. The secondary structures of these pyrene-DPA-PBLG polypeptides were investigated using Fourier transform infrared spectroscopy and wide-angle X-ray diffraction, revealing that the polypeptides with DPs of less than 19 were mixtures of α-helical and β-sheet conformations, whereas the α-helical structures were preferred for longer chains. Interestingly, pyrene-DPA-2NH2 exhibited weak photoluminescence (PL), yet the emission of the pyrene-DPA-PBLG polypeptides was 16-fold stronger, suggesting that attaching PBLG chains to pyrene-DPA-2NH2 turned on a radiative pathway for the non-fluorescent molecule. Furthermore, pyrene-DPA-2NH2 exhibited aggregation-caused quenching; in contrast, after incorporation into the PBLG segments with rigid-rod conformations, the resulting pyrene-DPA-PBLG polypeptides displayed aggregation-induced emission. Transmission electron microscopy revealed that mixing these polypeptides with multiwalled carbon nanotubes (MWCNTs) in DMF led to the formation of extremely dispersible pyrene-DPA-PBLG/MWCNT composites. The fabrication of MWCNT composites with such biocompatible polymers should lead to bio-inspired carbon nanostructures with useful biomedical applications.

Nitrogen self-doped carbon aerogels derived from trifunctional benzoxazine monomers as ultralight supercapacitor electrodes

Ultralight benzoxazine-derived porous nitrogen self-doped carbon aerogels with good yield can be prepared by direct polymerization of trifunctional benzoxazine monomers under acid catalysis using concentrated hydrochloric acid. This allows for a significantly widened density range (0.8-4.5 mg cm-3) and avoids any sacrificial etching. When serving as electrode materials for supercapacitors, the resulting hierarchical porous carbon aerogels show ultrahigh specific capacitance, excellent rate performance and good cycling stability (retention of 97.3% even after 10 000 continuous charge-discharge cycles). Besides energy storage devices, the interconnected nanoporous carbon aerogels can also find applications in oil/water separation, heavy metal removal, catalyst supports, and so forth.

Direct synthesis of poly(benzoxazine imide) from an ortho-benzoxazine: its thermal conversion to highly cross-linked polybenzoxazole and blending with poly(4-vinylphenol)

A facile one-pot synthesis of a poly(benzoxazine imide), NDOPoda Bz, was prepared without the need for either the preparation of an amino-functionalized benzoxazine or subsequent thermal treatment.

Polybenzoxazine/Polyhedral Oligomeric Silsesquioxane (POSS) Nanocomposites

The organic/inorganic hybrid materials from polyhedral oligomeric silsesquioxane (POSS, inorganic nanoparticles) and polybenzoxazine (PBZ) have received much interesting recently due to their excellent thermal and mechanical properties, flame retardance, low dielectric constant, well-defined inorganic framework at nanosized scale level, and higher performance relative to those of non-hybrid PBZs. This review describes the synthesis, dielectric constants, and thermal, rheological, and mechanical properties of covalently bonded mono- and multifunctionalized benzoxazine POSS hybrids, other functionalized benzoxazine POSS derivatives, and non-covalently (hydrogen) bonded benzoxazine POSS composites.

Bio-Inspired Supramolecular Chemistry Provides Highly Concentrated Dispersions of Carbon Nanotubes in Polythiophene

In this paper we report the first observation, through X-ray diffraction, of noncovalent uracil-uracil (U-U) dimeric π-stacking interactions in carbon nanotube (CNT)-based supramolecular assemblies. The directionally oriented morphology determined using atomic force microscopy revealed highly organized behavior through π-stacking of U moieties in a U-functionalized CNT derivative (CNT-U). We developed a dispersion system to investigate the bio-inspired interactions between an adenine (A)-terminated poly(3-adeninehexyl thiophene) (PAT) and CNT-U. These hybrid CNT-U/PAT materials interacted through π-stacking and multiple hydrogen bonding between the U moieties of CNT-U and the A moieties of PAT. Most importantly, the U···A multiple hydrogen bonding interactions between CNT-U and PAT enhanced the dispersion of CNT-U in a high-polarity solvent (DMSO). The morphology of these hybrids, determined using transmission electron microscopy, featured grape-like PAT bundles wrapped around the CNT-U surface; this tight connection was responsible for the enhanced dispersion of CNT-U in DMSO.