Thermal decomposition of hexamethylenetetramine: mechanistic study and identification of reaction intermediates via a computational and NMR approach

In a joint DFT and chemometrics study applied to NMR spectra, we disclose the structure of the main decomposition products of hexamethylenetetramine. The combination of these techniques enabled us to propose the structures of near-identical intermediates of the process and to unveil the structure of the main decomposition product of this priviliged structure.

Interphase Engineering of a Cellulose-Based Carbon Fiber Reinforced Composite by Applying Click Chemistry

Given our possible future dependence on carbon fiber reinforced composites, the introduction of a renewable matrix might be advantageous for the vision of a sustainable world. Cellulose is a superior green candidate and provides exceptional freedom in composite design as the free OH groups can be conveniently functionalized to give tailor-made materials. To obtain a high-performing carbon fiber reinforced cellulose propionate composite, we accurately tailored the interfacial adhesion by invoking click chemistry. The synthetic strategy involved grafting of a phenylacetylene structure onto the carbon fiber surface, onto which O-acylated 6-azido-6-deoxycellulose and a number of aromatic azides could be covalently attached. Single-fiber fragmentation tests indicated that the lipophilicity and size of the substituent on the deposited structure played a crucial role in determining molecular entanglement and mechanical interlocking effects, as penetration into the cellulose propionate matrix was of utmost importance. Enhanced interfacial shear strength was obtained for the carbon fiber covalently functionalized with the cellulose derivative. Nevertheless, the greatest increase was observed for the derivative substituted with a compact and highly lipophilic CF3 substituent. In a broader sense, our study provides a synthetic platform to bind cellulose derivatives to graphitic surfaces and paves the ways towards the preparation of innovative cellulose-based carbonaceous materials.

Carbon fibre reinforced cellulose-based polymers: intensifying interfacial adhesion between the fibre and the matrix

Interfacial interactions governing the interfacial adhesion between cellulose propionate and carbon fibre surface are placed under scrutiny to pave the way towards the development of green cellulose-based carbon fibre reinforced polymers. A range of molecular entities are deposited on the surface by initially grafting aromatic structures with appropriate functions via diazonium species followed by further derivatization of these entities. Cellulose propionate was also bound covalently to the surface via a tosylated derivative invoking its facile nucleophilic displacement reaction with surface-grafted amino functions. Significant increase in interfacial shear strength was obtained for the cellulose propionate-grafted carbon fibre composite as well as for the 4-(aminomethyl)benzene-functionalized sample, in the latter case possible hydrogen bonding took place with the cellulose propionate matrix. Furthermore, the positive effect of a highly lipophilic and yet compact -CF3 substituent was also noted. In order to let the grafted structure efficiently penetrate into the matrix, steric factors, lipophilicity and potential secondary interactions should be considered. It needs to be pointed out that we provide the first synthetic strategy to covalently bind cellulose derivatives to a largely graphitic surface and as such, it has relevance to carbonaceous materials being applied in cellulose-based innovative materials in the future.

Hyperstage Graphite: Electrochemical Synthesis and Spontaneous Reactive Exfoliation

Covalent modification of the π-electron basal planes of graphene enables the formation of new materials with enhanced functionality. An electrochemical method is reported for the formation of what is referred to as a Hyperstage-1 graphite intercalation compound (GIC), which has a very large interlayer spacing d001 > 15.3 Å and contains disordered interstitial molecules/ions. This material is highly activated and undergoes spontaneous exfoliation when reacted with diazonium ions to produce soluble graphenes with high functionalization densities of one pendant aromatic ring for every 12 graphene carbons. Critical to achieving high functionalization density is the Hyperstage-1 GIC state, a weakening of the van der Waals coupling between adjacent graphene layers, and the ability of reactants to diffuse into the disordered intercalate phase between the layers. Graphene functionalization with 3,5-dinitrophenyl groups provides for exceptional dispersibility (0.24 mg mL-1 ) in N,N-dimethylformamide and for conjugation with amines.

Versatile NiO/mesoporous carbon nanodisks: controlled synthesis from hexagon shaped heterobimetallic metal-organic frameworks

Hexagonal NiO/mesoporous carbon nanodisks (NiO/MCN) are facilely and controllably synthesized via constructing nickel-zinc trimesic acid heterobimetallic metal-organic framework (HMOF) disks before pyrolysis at 910 °C. Tailoring the Ni/(Zn + Ni) feed ratio and the reaction time during the HMOF synthesis creates a well-defined hexagonal carbon nanodisk with properly populated NiO nanocrystals while maintaining high porosity and conductivity. Such an elaborately fabricated NiO/MCN is highly stable, and exhibits the largest specific capacitance of 261 F g^-1 and the highest specific activity factor of 1.93 s^-1 g^-1 of any composite nanodisk during the capacitive test and 4-nitrophenol reduction, respectively.

Building Nanoporous Metal-Organic Frameworks "Armor" on Fibers for High-Performance Composite Materials

The nanoporous metal-organic frameworks (MOFs) "armor" is in situ intergrown onto the surfaces of carbon fibers (CFs) by nitric acid oxidization to supply nucleation sites and serves as a novel interfacial linker between the fiber and polymer matrix and a smart cushion to release interior and exterior applied forces. Simultaneous enhancements of the interfacial and interlaminar shear strength as well as the tensile strength of CFs were achieved. With the aid of an ultrasonic "cleaning" process, the optimized surface energy and tensile strength of CFs with a MOF "armor" are 83.79 mN m^-1 and 5.09 GPa, for an increase of 102% and 11.6%, respectively. Our work finds that the template-induced nucleation of 3D MOF onto 1D fibers is a general and promising approach toward advanced composite materials for diverse applications to meet scientific and technical demands.

Ru–Fe alloy mediated α-Fe2O3 particles on mesoporous carbon nanofibers as electrode materials with superior capacitive performance

Ru–Fe alloy mediated α-Fe₂O₃ particles on mesoporous carbon nanofibers were in situ fabricated and used as electrode materials with superior capacitive performance.

Interfacial properties and thermo-oxidative stability of carbon fiber reinforced methylphenylsilicone resin composites modified with polyhedral oligomeric silsesquioxanes in the interphase

The grafting of trisilanolphenyl-polyhedral oligomeric silsesquioxanes (trisilanolphenyl-POSS) onto carbon fibers (CFs) was achieved using toluene-2,4-diisocyanate (TDI) as the bridging agent.

One-step functionalization of carbon fiber using in situ generated aromatic diazonium salts to enhance adhesion with PPBES resins

In the present study, we developed a novel approach to introduce amino group (–NH₂), hydroxyl group (–OH) and sulfhydryl group (–SH) onto carbon fibers (CFs) using aromatic diazonium salts.

Interfacially reinforced carbon fiber/epoxy composites by grafting melamine onto carbon fibers in supercritical methanol

Carbon fiber was firstly functionalized with melamine in supercritical methanol to improve the properties of CF reinforced epoxy composites.

Modifying the carbon fiber–epoxy matrix interphase with silicon dioxide nanoparticles

The carbon fiber surface was modified by silicon dioxide nanoparticles by immersing CFs tows in a SiO₂ nanoparticle suspension. A significant increase of the IFSS was obtained.

Preparation and properties of carbon nanotube/carbon fiber hybrid reinforcement by a two-step aryl diazonium reaction

A two-step aryl diazonium reaction provides a simple and efficient method for fabricating the CNT/CF hybrids in aqueous solution without damaging the substrates.

Control interfacial properties and tensile strength of glass fibre/PP composites by grafting poly(ethylene glycol) chains on glass fibre surface

The interfacial adhesion increased as the grafted PEG chains became longer.

Bio-inspired polydopamine functionalization of carbon fiber for improving the interfacial adhesion of polypropylene composites

Carbon fiber was surface-functionalized by a facile dopamine self-polymerization method to improve the interfacial interaction with maleic anhydride grafted polypropylene modified PP.