Sufficient Functional Groups Research Articles

Photoelectrocatalytic CO2 Reduction to Methanol by Molecular Self-Assemblies Confined in Covalent Polymer Networks.

Inspired by the porous structures of photosynthetic organelles, we report here a new type of photoelectrode based on a standalone macroporous conjugated polymer network (MCN) that converts sunlight into high-energy electrons for CO2 reduction to CH3OH. The MCN provides supramolecular cavities with sufficient functional groups that control the structures of photocatalytic assemblies, which circumvents the geometric limitations of traditional inorganic counterparts. Stabilized interfacial contact between MCN and photocatalysts is achieved by strong chemical linkages throughout the network. Solar irradiation of MCN with a cobalt-based catalyst generates highly reducing electrons for the reduction of CO2 to CH3OH at a conversion efficiency of 70%. Production of CH3OH sustains for at least 100 h, with a small decrease in yield rates. Scaling up the photoelectrode from 1 to 100 cm2 results in photocurrent generation stabilized at 0.25 A and continuous CH3OH production at a conversion efficiency of 85%, demonstrating the scalability and high performances.

Heterogeneous MIL-88A on MIL-88B hybrid: A promising eco-friendly hybrid from green synthesis to dual application (Adsorption and photocatalysis) in tetracycline and dyes removal

Herein, the green synthesis of heterogeneous dual functional MIL88A-on-MIL88B hybrids (MIL: Materials InstituteLavoisier) with different amounts of MIL88B compared to MIL88A, including 1:2, 1:1, and 2:1, has been carried out. The photocatalytic degradation of tetracycline and adsorption of tetracycline and dyes (Direct Red 80, Direct Red 23, Acid Blue 92, and Reactive Orange 14) were investigated. Although the ratio of MIL88A-on-MIL88B (1:1) hybrid displayed the best activity, there is a slight difference in the photocatalytic performance of the other mass ratios studied. The result revealed that after 70 min of forming MIL88A on MIL88B, the best pollutant removal performance is obtained. During the limited synthesis time, the lopsided growth of MIL88A on the MIL88B surface limits the formation of sufficient functional groups and new pores between MIL88B as the substrate and MIL88A, which are effective and decisive in the performance. In the photocatalytic studies, the synthesized composite had good compatibility with the zero-order kinetics, and hydroxyl radicals were recognized as the most active species in the photocatalytic reaction. In the adsorption process, the MIL88A-on-MIL88A composite followed pseudo-second-order kinetics and the Langmuir isotherm. Besides, mechanisms such as π-π interaction/stacking, hydrogen bonding, and π-metal interaction were proposed for the pollutant adsorption process.

Advanced hybrid nanosheet membranes with stable nanochannels for ultrafast molecular separation

Lamellar graphene oxide (GO) membranes have gained substantial interest for molecular separation processes. However, GO membranes have shown inefficient separation performance levels due to their possession of sufficient functional groups that lead to swelling under applied hydraulic pressure. Herein, we demonstrate a highly stable and ultrafast filtrable graphene oxide-boron nitride (GOBN) hybrid membrane by incorporating boron nitride (BN) nanosheets into a GO membrane to restrict swelling and provide efficient hydraulic pressure separation characteristics. This new heterostructure retains the GOBN membrane microstructure and provides more nanochannels around the incorporation sites due to the small size of BN nanosheets; this phenomenon increases the permeance to 1310 Lm−2h−1bar−1, which is nearly six times higher than that of the pure GO membrane, with a high rejection reaching 99.2% for aqueous organic dyes. More importantly, the GOBN hybrid membrane shows an impressive permeance and dye molecule rejection performance characteristic across a range of organic solvents, such as methanol, ethanol, and isopropyl alcohol; the performance characteristics are better than those for the GO membrane. Our GOBN membrane with a stable microstructure opens opportunities for developing a high-performance multiple solvent nanofiltration membrane that surpasses the permeability-selectivity trade-off.

Ti3C2@g-C3N4/TiO2 Ternary Heterogeneous Photocatalyst for Promoted Photocatalytic Degradation Activities

Ternary heterojunction photocatalysts can improve the transport and separation of photogenerated electrons and holes, which could promote their reduction and oxidation properties for environmental and energy applications. In this research, the ternary photocatalyst Ti3C2@TiO2/g-C3N4 was successfully synthesized via direct electrostatic self-assembly during hydrothermal process. Ti3C2 MXene was used to optimize the interfacial carrier transport and separation between the interfaces. The obtained ternary heterostructured photocatalyst had a higher photocatalytic degradation performance for removing rhodamine B (RhB) and 4-chlorophenol (4-CP). The synergistic effect of heterojunction between g-C3N4 and TiO2 and Schottky barrier presented among TiO2 and Ti3C2 suppressed the recombination of the photogenerated electron–hole pairs. Moreover, the Ti3C2 can serve as an active site for the adsorption and activation of organic pollutants resulting from sufficient functional groups (F− here).

Variation in the Optical Properties of PEO-Based Composites via a Green Metal Complex: Macroscopic Measurements to Explain Microscopic Quantum Transport from the Valence Band to the Conduction Band.

In this study, a green chemistry method was used to synthesize polymer composites based on polyethylene oxide (PEO). The method of the remediation of metal complexes used in this study is an environmentally friendly procedure with a low cost. Zinc metal ion (Zn2+)-polyphenol (PPHNL) complexes were synthesized for two minutes via the combination of a black tea leaf (BTL) extract solution with dissolved Zn-acetate. Then, UV-Vis and FTIR were carried out for the Zn-PPHNL complexes in a liquid and solid. The FTIR spectra show that BTLs contain sufficient functional groups (O-H, C-H, C=O, C=C, C-O, C-N, and N-H), PPHNL, and conjugated double bonds to produce metal complexes by capturing the cations of Zn-acetate salt. Moreover, FTIR of the BTL and Zn-PPHNL complexes approves the formation of the Zn-PPHNL complex over the wide variation in the intensity of bands. The UV absorption spectra of BTL and Zn-PPHNL indicate complex formation among tea PPHNL and Zn cations, which enhances the absorption spectra of the Zn-PPHNL to 0.1 compared to the figure of 0.01 associated with the extracted tea solution. According to an XRD analysis, an amorphous Zn-PPHNL complex was created when Zn2+ ions and PPHNL interacted. Additionally, XRD shows that the structure of the PEO composite becomes a more amorphous structure as the concentration of Zn-PPHNL increases. Furthermore, morphological study via an optical microscope (OM) shows that by increasing the concentration of Zn-PPHNL in a PEO polymer composite the size of the spherulites ascribed to the crystalline phase dramatically decreases. The optical properties of PEO: Zn-PPHNL films, via UV-Vis spectroscopy, were rigorously studied. The Eg is calculated by examining the dielectric loss, which is reduced from 5.5 eV to 0.6 eV by increasing the concentration of Zn-PPHNL in the PEO samples. In addition, Tauc's form was used to specify the category of electronic transitions in the PEO: Zn-PPHNL films. The impact of crystalline structure and morphology on electronic transition types was discussed. Macroscopic measurable parameters, such as the refractive index and extinction coefficient, were used to determine optical dielectric loss. Fundamental optical dielectric functions were used to determine some key parameters. From the viewpoint of quantum transport, electron transitions were discussed. The merit of this work is that microscopic processes related to electron transition from the VB to the CB can be interpreted interms of measurable macroscopic quantities.

Adsorption performance and mechanism of cationic and anionic dyes by KOH activated biochar derived from medical waste pyrolysis

The massive generation of medical waste (MW) results in a series of environmental, social, and ecological problems. Pyrolysis is one such approach that has attracted more attention because of the production of value-added products with lesser environmental risk. In this study, the activated biochar (ABC600) was obtained from MW pyrolysis and activated with KOH. The adsorption mechanism of activated biochar on cationic (methylene blue) and anionic (reactive yellow) dyes were studied. The physicochemical characterization of biochar showed that increasing pyrolysis temperature and KOH activation resulted in increased surface area, a rough surface with a clear porous structure, and sufficient functional groups. MB and RYD-145 adsorption on ABC600 was more consistent with Langmuir isotherm (R2 ≥ 0.996) and pseudo-second-order kinetics (R2 ≥ 0.998), indicating chemisorption with monolayer characteristics. The Langmuir model fitting demonstrated that MB and RYD-145 had maximum uptake capacities of 922.2 and 343.4 mg⋅g−1. The thermodynamics study of both dyes showed a positive change in enthalpy (ΔH°) and entropy (ΔS°), revealing the endothermic adsorption behavior and randomness in dye molecule arrangement on activated-biochar/solution surface. The activated biochar has excellent adsorption potential for cationic and anionic dyes; hence, it can be considered an economical and efficient adsorbent.

Synthesis of PPC-graft-poly(PEOMA) Brush and PPC Gels via Post-polymerization Modification of Hydroxyl-Functionalized Poly(propylene carbonate)

Post-polymerization modification offers a facile and effective tool for adapting polymer properties. However, it has not been applied to poly(propylene carbonate) (PPC) as traditional PPC lacks sufficient functional groups along the polymer chain. In the present work, for the first time, hydroxyl-functionalized PPC has been prepared and used to construct PPC-brush and cross-linked polymer gels through post-polymerization modification approach. PPC-brushes in the form of PPC-graft-poly(PEOMA) were obtained with controllable brush length and brush density via “grafting from” a PPC-macroinitiator which was synthesized from esterification reaction of PPC-OH with 2-bromoisobutyryl bromide. PPC permanent networks in the form of dioxane gels were prepared by cross-linking PPC-OH with 4,4′-diphenylmethane diisocyanate (MDI). Rheological measurement of the gels showed that the cross-linking density scales linearly with the hydroxyl group density in PPC-OH. This work not only offers a facile strategy to realize the post-modification of PPC but also spurs the devising of innovative biodegradable materials with tailored molecular architectures.

Fully exposed silver nanoparticles stabilized on pH-responsive lignin-reactors for enhanced 4-nitrophenol reduction

Lignin as an advanced catalyst support has attracted much attention owing to its sufficient functional groups and natural cross-linked network structure, as well as good biodegradability. Herein, we fabricate a pair of lignin-reactors with silver nanoparticles (Ag NPs) supported outside or embedded in pre-hydrolyzed lignin (designated as Ag/PL or Ag@PL, respectively) via the self-assembly approach, which could be used for efficient catalytic reduction of 4-nitrophenol (4-NP). Through this strategy, the phase transitions and morphology changes of reactors could be achieved based on the pH responsiveness of lignin. The resultant Ag/PL exhibits a much higher catalytic activity (TOF 5.2 × 103 h−1, k 4.8 × 10−2 s−1) as compared to that of Ag@PL (TOF 2.5 × 103 h−1, k 2.3 × 10−2 s−1) under a low NaBH4 concentration (n[NaBH4]/n[4-NP], 100) at room temperature, which notably surpasses those of previously reported carbon-supported catalysts. The enhanced catalytic performance of Ag/PL is attributed to the fact that the fully exposed Ag NPs on the interface possess close proximity to the reactant. This work not only provides a promising route to design advanced catalysts in wastewater treatment system, but also paves the way for lignin valorization into functional-materials.

Reduced graphene oxide nanofluidic electrolyte with improved electrochemical properties for vanadium flow batteries

Development of the Vanadium Redox Flow Battery (VRFB) has been widely reported but typically only focuses on one part of the cell (e.g. electrode, electrolyte, or membrane). Improvement to a single part of the cell may cause side effects on other parts during long-term cycling leading to an overall drop in the performance of the battery. To avoid this, the use of nanofluidic electrolyte seems to be a promising approach to enhance the performance of both electrode and electrolyte simultaneously. This paper aims to investigate the electrochemical performance of a newly prepared reduced graphene oxide (rGO) nanofluidic vanadium electrolyte, applicable for Vanadium Redox Flow Batteries (VRFB). Herein, we report for the first time a stable rGO/vanadium nanofluidic electrolyte with improved electrochemical performance. Benefiting from the low degree of oxidation as compared to GO, the rGO can provide high electrical conduction due to the presence of sufficient functional groups, which can facilitate the redox reactions. The effect of various concentrations of rGO on the electrochemical performance is investigated. The current collector (carbon cloth (CC) electrode) was further characterized using different physico-chemical techniques to underpin the stability of rGO nanofluids. The results suggested that the electrochemical performance of vanadium electrolyte increases with the concentration of rGO. Improvements of approx. 15% to 20% were achieved in peak potential separation and current density rates, respectively. In addition, the incorporation of rGO in nanofluidic electrolyte significantly decreases the electrolyte and charge transfer resistance by ∼10% and ∼99%, respectively, and improves the vanadium ion diffusion process by ∼50%.

Nanocatalyst in remediating environmental pollutants

The gradual increase of population and residues excreted from advance industries disturbs our ecological balance. The report of change in climate and environmental pollution is most hot topic around the world. Environmental pollution has become a threat to our life as it may be the root causes of different unwanted diseases. Hence, the degradation of this pollutants are required immediately. However, there are some pollutants which are very hard to degrade and needs more time for remediation. In this process, the novel work of nanotechnology can be applied and the pollutants can be transformed into a harmless one or can be properly remediate. It is possible because of their large surface area, active sites and sufficient functional groups. Besides these, it could transform strong surface complexes with various kinds of pollutants and thereby could efficiently eliminate the pollutants from the aqueous solutions. As a result, nanocatalyst and nanomaterials are generally used for the remediation process. Different kind of nanomaterials including inorganic, carbon materials and polymeric based materials are used in remediation of environment contaminants. Utilizing these novel materials can successfully purified pollutants like heavy metals, dyes, chlorinated organic compounds, organophosphorus compounds, volatile organic compounds, and halogenated herbicides. Furthermore, process like adsorption and photocatalytic reduction of organic pollutants and the adsorption or reduction process of heavy metal ions are usually considered as the one of the major methods to reduce the concentration of pollutants in the surroundings. In context to this, the present review writes up more on enhancement work of nanocatalyst in remediation of environment pollutants and there need for future to bring a clean safety environment.

Modification of ZIF-8 on bacterial cellulose for an efficient selective capture of U(VI)

MOFs are confined to solid supports to overcome their inherent disadvantages of lightweight and submicron size, which pose challenges to the adsorption operation. ZIF-8 nanoparticles can be loaded onto bacterial cellulose (BC) in a simple manner, and subsequently carbonized at 700 °C to obtain a larger specific surface area (expressed as BC@ZIF-8 carbon aerogels (BZCA). SEM indicates that ZIF-8 was successfully self-assembled on bacterial cellulose. Various characterization techniques (SEM, TEM, FT-IR, XRD, BET, and XPS) indicated that BZCA had been successfully prepared, with a large specific surface area (220.45 m2/g) and sufficient functional groups (-NH-, -OH, Zn–O, N–O, and C = N-). The relationship of the adsorption of BZCA to UO22+ with both contact time and initial concentration was then studied. Results showed that the adsorption of UO22+ followed a pseudo-second-order kinetic model (R2 = 0.999). After calculation, the maximum adsorption capacity of BZCA was 535 mg/g, which was comparable to or better than that of other adsorbents. The kinetic analysis disclosed that 70 min was enough for BZCA to reach the adsorption equilibrium. The adsorption mechanism of the prepared adsorbent on UO22+ was studied by FTIR and XPS.

Miscanthus as a carbon precursor for graphene oxide: A possibility influenced by pyrolysis temperature

This study investigates the potential of producing graphene oxide (GO) from biomass via green (comparatively) processing and the impact of graphitization temperature on GO quality. Our findings show that it is possible to convert biomass into highly pyrolytic biochar, followed by shear exfoliation to produce few-layer GO. However, pyrolysis temperature is key in ensuring that the biochar is suited for effective exfoliation. Low temperatures (<1000 °C) would preserve undesirable heterogenous, complex cellular structure of biomass whilst excessive temperatures (≥1300 °C) result in uncontrolled melting, coalescence and loss of functional groups. Results show 1200 °C to be the optimum graphitization temperature for miscanthus, where the resultant biochar is highly aromatic with sufficient functional groups to weaken van der Waals forces, thus facilitating exfoliation to form 6-layer GO with specific surface area of 545.3 m2g−1. This study demonstrates the potential of producing high quality, fit-for-purpose graphene materials from renewable sources.

Durable functionalization of polyethylene terephthalate fabrics using metal oxides nanoparticles

The share of polyester (polyethylene terephthalate, PET) in textiles has been continuously increasing over the last several years due to its high mechanical durability and low cost and has reached 80%. However, polyester suffers from many problems and most of them arise from its poor hydrophilicity and inability to get functionalized as it lacks sufficient functional groups on its surface. In this study, a facile method is reported to impart durable functionalization of PET substrate, wherein different metal oxide NPs were mixed with a nonreactive hydrophilic resin and applied on the fabric using a simple pad-dry-cure method. The treated PET fabrics were characterized for changes in the surface morphology and chemical composition both in as-applied state and after several cycles of laundry washes. The treatment effectively and durably enhanced the hydroxyl group concentration on the surface of PET fabric even with the application at a very low concentration of ∼ 1 wt%, which is very critical for its industrial viability. This finishing methodology opens up the possibility of imparting durable functionalities such as photocatalytic, UV absorption, antistatic, and/or moisture management properties to otherwise inert hydrophobic PET fabric.

Uniform, Scalable, High-Temperature Microwave Shock for Nanoparticle Synthesis through Defect Engineering

Summary Here we demonstrate a thermal shock synthesis method triggered by microwave irradiation for the rapid synthesis of nanoparticles on reduced graphene oxide (RGO) substrate. With properly controlled reduction, RGO has high electrical conductivity while maintaining functional groups, leading to an extremely efficient microwave absorption of ∼70%. The high utilization of microwaves results in the ability to raise the temperature to 1,600 K in just 100 ms, which is followed by rapid quenching to room temperature. The defects on the RGO are crucial for achieving this record-high microwave-induced temperature as these defects play a fundamental role in absorbing the radiation as well as the self-quenching mechanism. By loading precursors onto RGO, we can utilize rapid temperature change to synthesize nanoparticles. The nanoparticles are ∼10 nm with uniform distribution. This facile, rapid, and universal synthesis technique has the potential to be employed in large-scale production of nanomaterials and suggests a new direction for nanosynthesis.

Magnetic metal-organic frameworks (Fe3O4@ZIF-8) composites for U(VI) and Eu(III) elimination: simultaneously achieve favorable stability and functionality

The water stable core-shell microspheres (Fe3O4@ZIF-8) with strong magnetism were successfully fabricated through a facile modification strategy. Concrete procedures included firstly pretreatment of Fe3O4 core with anionic polyelectrolyte to acquire negatively charged Fe3O4 particle surface, followed by nucleation through attracting Zn2+ cation, and then growth of a thin layer of ZIF-8 (~25 nm). Various characterization techniques (SEM, TEM, FT-IR, XRD, VSM, BET and XPS) indicated that the Fe3O4@ZIF-8 microspheres were highly stable and magnetic with a large specific surface area (606.91 m2/g) and fairly sufficient functional groups (NH, OH, COOH, ZnO, NO and CN). Multi-factors affecting the radionuclides removal performance on Fe3O4@ZIF-8 was adequately explored, comprising contact time, temperature, pH, ionic strength, co-existing ions and extreme conditions. And the results showed that Fe3O4@ZIF-8 exhibited fast reaction kinetics (~30 min to achieve equilibrium), excellent uptake capabilities (539.7 mg U/g and 255.6 mg Eu/g), remarkable selectivity and favorable physicochemical stability. These researches suggested that Fe3O4@ZIF-8 could not only simultaneously achieve favorable stability and functionality, but also easily to be separated by external magnetic field after used in radioactive sewage treatment, which was of considerable practical utility in extracting radioactive wastes though in harsh circumstance.

Scalable and Efficient Electrochemical Exfoliation of Graphite Felt As High-Performance Flow Battery Electrode

Mass production of highly active graphite felt (GF) electrode is necessary to attain high power density and energy efficiency, which is essential to reduce the cost and enable the extensive industrial application. Herein, for the first time, we report a rapid and scalable electrochemical exfoliation of the GF in aqueous solution by breaking the weak van der Waals forces between the greaphitic layers through anion intercalation. The expansion of the graphite layers creates a distinctive layer by layer structure and introduces sufficient functional groups that intensifies the abundance of electrochemically active surface area resulting enhanced kinetics at the electrode-electrolyte interface and improved wettability enabling better electrolyte accessibility. Consequently, a rapid and reversible redox reactions with minimized overpotential and high volumetric capacity was achieved. In addition, the exfoliated GF (E-GF) electrode deliver voltage and energy efficiencies of 98.53 and 90.96 % at 40 mA cm-2 and 61.86 and 52.90 % at a high current density of 200 mA cm-2, individually. Compared to the traditional GF treatment method, by eliminating the high temperature and high energy consuming synthesis processes, our approach of electrochemical exfoliation is much faster and energy efficient. These results suggest the enormous potential of the exfoliated GF owing to its excellent electrochemical activity combined with its rapid, facile, and scalable nature.

Protein Shell-Encapsulated Pt Clusters as Continuous O2-Supplied Biocoats for Photodynamic Therapy in Hypoxic Cancer Cells.

As a highly oxygen-dependent process, the effect of photodynamic therapy is often obstructed by the premature leakage of photosensitizers and the lack of oxygen in hypoxic cancer cells. To overcome these limitations, this study designs bovine serum albumin protein (BSA)-encapsulated Pt nanoclusters (PtBSA) as O2-supplied biocoats and further incorporates them with mesoporous silica nanospheres to develop intelligent nanoaggregates for achieving improved therapeutic outcomes against hypoxic tumors. The large number of amino groups on BSA can provide sufficient functional groups to anchor tumor targeting agents and thus enhance the selective cellular uptake efficiency. Owing to the outstanding biocompatibility features of BSA and the state-of-the-art catalytic activity of Pt nanoclusters, the nanocomposites have lower dark cytotoxicity, and O2 continuously evolves via the decomposition of H2O2 in a tumor microenvironment. Both in vivo and in vitro experiments indicate that the resulting nanocomposites can effectively relieve hypoxic conditions, specifically induce necrotic cell apoptosis, and remarkably hinder tumor growth. Our results illuminate the great potential of BSA-encapsulated Pt nanoclusters as versatile biocoats in designing intelligent nanocarriers for hypoxic-resistant photodynamic therapy.

Surface-Modified Biochar with Polydentate Binding Sites for the Removal of Cadmium.

In this study, a surface chemical-modified rice husk biochar with abundant amino groups and disulfide bonds for the removal of cadmium was prepared using cystamine dihydrochloride as a modification ligand and glutaraldehyde as a crosslinker. The biochars were characterized by Fourier transform infrared spectrometry (FTIR), elemental analysis, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetry analysis (TGA), and nitrogen sorption (BET) before and after modification. The adsorption properties of the modified biochars for Cd (II) were investigated in detail via adsorption isotherm models, adsorption kinetics models, and selective adsorption experiments. The surfaces of the cystamine-modified biochars with granular nanopolymers of sufficient functional groups of primary amine and disulfide linkage rendered the biochar surface more conducive to electrostatic attraction and surface complexation. The theoretical maximum adsorption capacity of the modified biochars (81.02 mg g−1) was almost 10-fold greater than that of the raw biochars (8.347 mg g−1) for Cd (II). Besides, the cystamine-modified biochars had a better affinity for Cd (II) compared to other heavy metals (Zn, As, Cd, Co, Ni, Cr), showing six-fold greater affinity for Cd (II) than Zn2+. The results of this study indicate that the modification of biochars derived from rice husks shows great potential in the removal of Cd (II) from contaminated water.

Novel wet pyrolysis providing simultaneous conversion and activation to produce surface-functionalized biochars for cadmium remediation

The enhancement of surface functional groups of biochar is essential to improving the biochar contaminant adsorption. Current pyrolysis methods that are accompanied by activation are energy consuming and costly. Herein, a novel wet-pyrolysis system that was carried out in open air, with simultaneous conversion and modification to produce an effective biochar adsorbent, is described. Within this system, the surface of the biochar was oxidized partially to produce sufficient functional groups at the surface, whereas carbonization of the biomass (miscanthus sacchariflora) occurs under an acidic catalyst. The characteristic results confirmed the attachment of abundant surface functional groups, including hydroxyl and carboxyl groups, which increased in content with the ongoing reaction time. Neutralization with sodium carbonate removed the hydrogen bonds and enhanced the adsorption properties. The biochar that was obtained by using this technique exhibited an excellent cadmium adsorption capacity of 197 mg .g−1 and a high removal efficiency of 99%. Analysis of the Cd-loaded biochar indicated that adsorption occurred via ion exchange, and formed cadmium complexes. It could be concluded that this novel wet-pyrolysis system is a promising approach to produce biochar efficiently and cost-effectively for heavy-metal remediation.

Comparison of rigid and flexible structural daimines grafted carbon fiber for enhancing the interfacial and mechanical properties of carbon fiber/epoxy composites

ABSTRACTInterfacial strength between fiber and matrix is an important factor affecting the mechanical properties of carbon fiber composites. Different daimines, ethylenediamine (EDA) and p-phenylenediamine (PPD), were grafted on carbon fiber to enhance interfacial strength of composites. Functional groups and chemical composition were tested by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Thermaogravimetric analysis and Roman spectroscopy. Scanning electron microscope was used to characterized surface morphology. Results revealed that EDA with flexible structure was more easily grafted onto surface. In contrast, PPD with rigid structure could improve the interfacial performance better. More importantly, carbon fiber grafted on both EDA and PPD had the highest wettability and interlaminar shear strength owing to the presence of sufficient functional groups on carbon fiber surface. Compared with untreated carbon fibers, the surface energy and the interlaminar shear strength of the grafted EDA and PPD carbon fibers increased by 38.57% (50.98 mN/m) and 44.81% (69.8 MPa) respectively. The investigation provides an approach to enhance the mechanical properties of fiber composites by controlling the structure of grafted components.