Interfacial Agent Research Articles

Selective laser sintering of PEG treated inorganic fullerene-like tungsten disulfide nanoparticles/polyamide 12 nanocomposites and fire safety behavior

Research has focused on developing advanced polyamide 12(PA12) engineering plastics with low flammability and low levels of smoke evolution during combustion. To satisfy green and safe industrial criteria, it is essential to minimize the emission of smoke and harmful gases generated during the burning of PA12. As a result, utilizing inorganic fullerene-liked tungsten sulfide (IF-WS2) nanoparticles as the precursor and polyethylene glycol (PEG) as the interfacial functional agent, a flame retardant grafted with the –OH functional group on the surface of IF-WS2 nanoparticles was designed and synthesized. Selective laser sintering (SLS) was used to fabricate the PA12/F-IF-WS2 nanocomposites. The multiple –OH groups provided by PEG could enhance the hydrogen bonding active sites of F-IF-WS2 nanoparticles and PA12 molecular chain groups, which could further boost the flame-retardant efficiency of PA12. The apparent decline in the peak heat release (26.55%), peak smoke generation (23%), and total CO production (40.4%) values proved the increased fire safety of the PA12 composite. Depending on the characterization results, a possible flame-retardant mechanism was proposed. Furthermore, the addition of F-IF-WS2 had a decisive effect on mechanical properties, including tensile properties, and dynamic mechanical properties. The PA12/F-IF-WS2 nanocomposites prepared using SLS molding provide a new direction for preparation and flame-retardant applications.

Effect of Hybrid Fillers of Bamboo Fiber and Commercial Glass Fiber on High Density Polyethylene Matrix

The focus of this research work is to study the effect of hybrid fillers of bamboo fiber and commercial glass fiber on high density polyethylene (HDPE) matrix without interfacial coupling agent. The hybrid composite was formed through melt blending method using two-roll mixing mill at temperature of 160 oC and was shaped using compression molding machine. The highest value of Tensile Modulus at break and Hardness were obtained at hybrid ratio of 70 % of HDPE/ 15 % bamboo/ 15 % glass particles (H/B15/G15). However, the inclusion of the hybrid fillers did not show any significant difference in Impact strength from the molded blank HDPE samples (H/B0/G0) while the percentage water absorbed by the samples predominantly decreased as the content of the commercial glass filler was increase in the HDPE matrix.

Experimental Study on the Property and Mechanism of the Bonding Between Rubberized Concrete and Normal Concrete

Scholars have studied the impact of rubber particles (RPs) on the performance of the concrete and the research topics have covered all the mechanical properties and durability of normal concrete (NC). Recently, scholars have turned their research interest to the structural properties of concrete. However, there are few experimental studies on the bonding properties of RC to NC. The RPs have both positive and negative impacts on the bond performance. On one hand, RPs can reduce the shrinkage of concrete, resulting in reduced shear stress and tensile stress near the bonding boundary. On the other hand, RPs cause a reduction in the overall strength of concrete, resulting in the poor mechanical performance of the interface transition layer between the two concrete. The test results of this study show that the bonding splitting tensile strength between freshly mixed RC to aged NC first increases and then decreases with the rise of the RPs content in the RC, and the bonding splitting tensile strength reaches the peak when the RPs content is 10%. The bonding splitting tensile strength between the NC and the RC mixed with 3–5 mm RP is higher than that between the NC and the RC mixed with 1–3 mm RPs. When mixed with modified RPs, the bonding splitting tensile strength between the RC and the NC is improved. Applying an interfacial agent (a cement slurry or an epoxy) on the old concrete bonding surface can significantly improve the bonding splitting tensile strength. The results of non-repeated two-way ANOVA show that the content of the RPs and the type of the interfacial agent have significant effects on the bond splitting tensile strength, while the size and modification of the RPs have no significant effects on the bond splitting tensile strength.

Cement-Based Repair Materials and the Interface with Concrete Substrates: Characterization, Evaluation and Improvement.

Surface damages usually occur in concrete structures. In order to restore the functions and prolong the service life of concrete structures, their surface damages should be repaired in time. This paper reviews the main requirements for repair materials for concrete structures and the most used inorganic repair materials, such as cement-based materials, alkali-activated materials and polymer modified inorganic repair materials. Moreover, techniques to characterize and even improve the interfaces between these repair materials and concrete substrate are summarized. Cement-based material has the advantages of good mechanical properties and consistency with concrete substrate while having the problems of high shrinkage and low flexibility. Polymer modified materials were found as having lower shrinkage and higher flexural strength. Increasing the roughness or humidity of the surface, adding fibers and applying interfacial agents can improve the bond strength between cement-based repair materials and concrete substrates. All of these repair materials and techniques can help to build a good interfacial bonding, and mechanisms of how they improve the interface are discussed in this article. These are of great importance in guaranteeing the effectiveness of the repair of the concrete surface and to guide the research and development of new repair materials.

Molecular Interface Engineering via Triazatruxene‐Based Moieties/NiOx as Hole‐Selective Bilayers in Perovskite Solar Cells for Reliability

Interface engineering is an effective approach to decrease nonradiative recombination and the energy barrier at the perovskite/hole transporting layer (HTL) interfaces. To overcome such limitations, an organic semiconductor (DTT‐EHDI 2 ) is proposed, which is, composed of dithienothiophene (DTT) as the core and a planar triazatruxene incorporating an alkyl chain as the side group. This is noted to be an effective interfacial layer for inverted planar perovskite solar cells (PSCs). The altered interface effectively minimizes the detrimental charge recombination and tailors the photoinduced charge transfer dynamics at the interface of the inorganic HTL/perovskite. The π‐conjugation in DTT‐EHDI 2 induces high hole mobility and electrical conductivity via electron‐donating properties and strong π–π intermolecular interaction. The synergetic approach leads to a substantial performance enhancement in dopant‐free DTT‐EHDI 2 ‐based inverted planar PSCs, achieving 18.15% power conversion efficiency with negligible hysteresis effect. The present approach provides an effective direction of the cost‐effective thiophene derivative as an interfacial agent to escalate the optoelectronic performances in photovoltaics.

Study on the interfacial shear performance between engineered cementitious composites and concrete after being subjected to high temperatures

This paper researched the interfacial shear performance between engineered cementitious composites (ECC) and concrete after exposure to high temperatures. A total of 13 groups of 35 Z-shaped specimens were manufactured and subjected to direct shear tests. The test parameters included the maximum temperature experienced by the concrete part, the surface roughness of the substrate concrete, cooling regimes of the concrete part, fibre category of ECC, and interfacial agents. The test results showed that below 400 °C, the interfacial shear strength increased with temperature while the interfacial shear strength decreased with increasing temperature above 400 °C. Similarly, below 3.5 mm, the interfacial shear strength increased with the surface roughness of the substrate concrete while above 3.5 mm, the interfacial shear strength decreased with increasing surface roughness. Specimens with PE-ECC exhibited better interfacial performance than those with PVA-ECC. The interfacial strength of the specimens decreased if the concrete part was water-cooled or its interface treated with fly ash or cement paste. A mathematical model was proposed to predict the interfacial shear strength of the Z-shaped specimens and a digital image correlation (DIC) technique was utilized to measure the strain field of the specimens.

Emulsion dipping based superhydrophobic, temperature tolerant, and multifunctional coatings for smart strain sensing applications

Superhydrophobic and electrically conductive coatings with multifunctionality have promising applications especially in the field of flexible electronics; however, developing the multi-functional coating with excellent durability, high temperature tolerance and corrosion resistance is still a challenge. Here, a novel emulsion dipping based strategy is, for the first time, proposed for preparation of the superhydrophobic smart coating. A substrate coated with the Ag precursor is dipped into an oil-in-water emulsion with the PDMS as the oil phase and aqueous reductant solution as the water phase while the curing agent of PDMS as the emulsifier. Ag precursor is reduced to Ag nanoparticles (AgNPs), while at the same time, the water evaporation produces the porous structure on the surface, and PDMS is served as both the interfacial adhesion agent and low surface energy agent. The obtained superhydrophobic and anti-corrosive AgNPs@PDMS coating possess a high electrically conductivity (up to 102 S/cm) and hence excellent Joule heating performance. The coating shows stable conductivity and superhydrophobicity after it experiences abrasion, bending, acid and ultrasonication treatment, performing outstanding stability and durability. Even exposed to a high temperature of 120 °C for 10 h, the AgNPs@PDMS coating can keep its water contact angle and conductivity unchanged, displaying a high temperature tolerance. The AgNPs@PDMS can also be coated onto the elastic polymer fabric and foam to fabricate strain and piezoresistive sensors with a large working strain range, high sensitivity, ignorable sensing hysteresis and excellent reusability.

Interfacial crosslinking enabled super-engineering polymer-based composites with ultra-stable dielectric properties beyond 350 °C

The polymer composites exhibiting reliable dielectric properties at high temperatures (>300 °C) are urgently required for cutting-edge electronic applications. In the present work, an interfacial reactive agent named 4-aminophxylphthalonitrile (4-APN), was covalently modified on the surface of the multiwalled carbon nanotubes (MWCNTs) to prepare the nitrile-functionalized multiwalled carbon nanotubes (MWCNTs-CN), which was further incorporated into the phthalonitrile end-capped polyarylene ether nitrile (PEN-ph) matrix to fabricate the high-temperature resistant PEN-ph/MWCNTs-CN composites. It was found that through facile heat-treatment, the crosslinked PEN-ph/MWCNTs-CN (7 wt%) composites exhibited a high glass transition temperature of 430 °C and stable dielectric properties (dielectric constant of 22.08 at 1 kHz) up to 350 °C. Meanwhile, the energy storage density of the composite membrane increased from 0.59 to 2.18 J/cm3 with the increase of filler content, showing an increase of 269.5%. The nitrile-functionalization of MWCNTs can not only improve the interfacial compatibility between MWCNTs-CN and PEN-ph matrix resin but also make MWCNTs-CN play a role as a crosslinker to further improve the mechanical, thermal, and dielectric properties of the composites. Therefore, the PEN-ph/MWCNTs-CN composites prepared by interfacial crosslinking reaction in this work will serve as the candidate materials for high-temperature-resistant energy storage applications.

Effective Interface Defect Passivation via Employing 1-Methylbenzimidazole for Highly Efficient and Stable Perovskite Solar Cells.

Although the power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) have made great progress, the surface and interface defects still affect their PCE and stability and hinder the commercialization. To overcome this problem, 1-methylimidazole (1-MIm) and 1-methylbenzimidazole (1-MBIm) were used as the interfacial passivation agents to passivate the defects at surface and interface. The results indicated that, in contrast to 1-MIm, 1-MBIm displayed a stronger Lewis coordination interaction with the uncoordinated Pb2+ to reduce the non-radiative recombination and also effectively improved the charge transfer capacity of perovskite films due to its strong π-π conjugate interaction, resulting in the better photovoltaic performance. As a result, the PCE of the champion 1-MBIm PSC was improved from 19.48 (pristine) to 21.22 % with a dramatically enhanced open-circuit voltage (Voc =1.15 V). More importantly, a significant improvement in long-term stability was achieved for 1-MBIm perovskite devices, which was attributed to the high-quality perovskite film caused by the strong passivation effect of 1-MBIm and the hydrogen bond with water molecules. The results offers an efficient and facile strategy by interface engineering to fabricate high-performance and stable PSCs for commercial application.

A Molecular‐Level Interface Design Enabled High‐Strength and High‐Toughness Carbon Nanotube Buckypaper

AbstractBuckypaper (BP) assembled by carbon nanotubes (CNTs) is considered as a promising macroscopic material with excellent multifunctional properties. However, the poor interfacial stress‐transfer ability between CNTs seriously limits its further applications. This paper proposes a novel approach to simultaneously improve both the tensile strength and the toughness of BPs, where a commercial poly(amido amine) (PAMAM) dendrimer is utilized to serve as an interfacial bridging agent, by realizing effective chemical cross‐linking between CNTs. The result shows that the introduction of PAMAM can increase the tensile strength, Young's modulus, and toughness by 306%, 168%, 1007%, respectively, compared with that of pristine BPs based on weak van der Waals interactions. In addition, molecular dynamics (MD) simulation is employed to reveal the proposed interfacial enhancement. It is found that the elastic deformation, uncoiling, interlocking of PAMAM dendrimers, and chemical bonds between PAMAM dendrimers and CNTs contribute to the improvement of the macroscopic strength and toughness of BPs. More importantly, it is found that the formed amido bonds are very strong, and the breakage of chemical bonds occurs at C─N bonds within PAMAM themselves. This work provides a new route for interfacial structure design and an in‐depth understanding of mechanical properties of BPs.

1T-rich 2D-WS2 as Interfacial Agent to Escalate Photo-induced Charge Transfer Dynamics in a Dopant-free Perovskite Solar Cells

1T-rich 2D-WS2 as Interfacial Agent to Escalate Photo-induced Charge Transfer Dynamics in a Dopant-free Perovskite Solar Cells

Hydrophobic wrapped carbon nanotubes coated cotton fabric for electrical heating and electromagnetic interference shielding

Load conductive component onto textiles via coating method is a simple and facile fabrication process to prepare flexible smart wearable device. However, this functional textile will suffer a significant damage after washing or mechanical wear, which hindered its application. In this study, polydopamine (PDA) was used as an interfacial agent to enhance the combination between carbon nanotubes (CNTs) and cotton fiber to fabricated a highly conductive fabric. Furthermore, a hydrophobic material 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) was introduced to the conductive fabric via dip-coating process, which effectively fixed the CNTs and simultaneously realize the water resistance of the composite fabric, as the contact angle for the fabric was up to 138°. Owning to the formation of a stable conductive path, the composite conductive fabric always possessed a surface resistance lower than 110 Ω/sq. Even after going through the repeated mechanical deformation or multiple stripping cycles, this conductive pathway of the composite fabric was still well maintained. Benefit from the excellent stability and high electrical conductivity, this fabric shows an attractive electromagnetic (EMI) shielding performance, as its EMI shielding effectiveness was 22 dB under 6.57–9.99 GHz and 23 dB under 11.9–18 GHz. Furthermore, the fabric exhibited an outstanding electric heating performance with the heating temperature reaches more than 85 °C at 6 V. Along with the facile preparation technique and stable functional performance, we expect that this hydrophobic conductive cotton fabric can be used as wearable electronics and for the design of various smart flexible devices.

Mitigating the Agglomeration of Nanofiller in a Mixed Matrix Membrane by Incorporating an Interface Agent.

Nanodiamonds (ND) have recently emerged as excellent candidates for various applications including membrane technology due to their nanoscale size, non-toxic nature, excellent mechanical and thermal properties, high surface areas and tuneable surface structures with functional groups. However, their non-porous structure and strong tendency to aggregate are hindering their potential in gas separation membrane applications. To overcome those issues, this study proposes an efficient approach by decorating the ND surface with polyethyleneimine (PEI) before embedding it into the polymer matrix to fabricate MMMs for CO2/N2 separation. Acting as both interfacial binder and gas carrier agent, the PEI layer enhances the polymer/filler interfacial interaction, minimising the agglomeration of ND in the polymer matrix, which is evidenced by the focus ion beam scanning electron microscopy (FIB-SEM). The incorporation of PEI into the membrane matrix effectively improves the CO2/N2 selectivity compared to the pristine polymer membranes. The improvement in CO2/N2 selectivity is also modelled by calculating the interfacial permeabilities with the Felske model using the gas permeabilities in the MMM. This study proposes a simple and effective modification method to address both the interface and gas selectivity in the application of nanoscale and non-porous fillers in gas separation membranes.

Tailored conductive fullerenes-based passivator for efficient and stable inverted perovskite solar cells

Interfacial defects result in a limitation to the development of highly efficient and stable perovskite solar cells. The passivation of these defects by adopting various interfacial defects passivation agents is a common method for boosting device performance. However, most existing interfacial defects passivation agents form poorly conductive aggregates at the perovskite interface with the electron transport layer (ETL), hindering the transport of charge carriers. In addition, the electron mobility of passivation agents is an important factor that affects the electron communication between the adjacent layers. Herein, a fullerene-based molecular passivator, [60]fullerene-4-(1-(4-(tert-butyl)phenyl)pyrrolidin-2-yl)benzenaminium (C60-tBu-I), is designed and synthesized. This novel n-doping fullerene ammonium iodide is developed as an interfacial modification agent to accelerate charge transport from the perovskite active layer into the ETL while hindering the nonradiative charge carrier recombination. Hence, compared with the control devices (15.66%), C60-tBu-I-modified device presents a higher efficiency of 17.75%. More importantly, the tert-butyl group dramatically enhances the resistance of perovskite films to water molecular. As a result, C60-tBu-I-modified devices exhibit excellent long-term stability, remaining at more than 87% of the initial power conversion efficiency value after storage for 500 h.

Adsorption of phenylalanine-rich sequence-defined oligomers onto Kevlar fibers for fiber-reinforced polyolefin composite materials

Oligomers comprising four or sixteen phenylalanine residues with regularly intercalated aliphatic chains of different lengths prepared by solid-phase synthesis exhibit sufficient thermal stability to be used as interfacial agents and processed for the preparation of poly(propylene-co-ethylene)-based composite materials. The investigation of their adsorption on Kevlar fibers by SEM is difficult due to the surface heterogeneity of the bare Kevlar fibers. However, oligomers with four successive phenylalanine residues have been clearly observed suggesting their better adsorption on the fiber. The quantification of those oligomers adsorbed on the fibers performed gravimetrically on pellets of fibers has however revealed no significant impact of the length of the aliphatic chain.

1T-Rich 2D-WS2 as an interfacial agent to escalate photo-induced charge transfer dynamics in dopant-free perovskite solar cells

The deficiency in the photo-induced charge transfer dynamics at the perovskite-charge transport layer interfaces due to depleted energy alignment and surface traps impedes perovskite solar cells performance improvement. Herein, we suggest a simplistic interfacial engineering protocol to overcome current challenges.

Hierarchical Assemblies of Polymer Particles through Tailored Interfaces and Controllable Interfacial Interactions

AbstractHierarchical assembly architectures of functional polymer particles are promising because of their physicochemical and surface properties for multi‐labeling and sensing to catalysis and biomedical applications. While polymer nanoparticles’ interior is mainly made up of the cross‐linked network, their surface can be tailored with soft, flexible, and responsive molecules and macromolecules as potential support for the controlled particulate assemblies. Molecular surfactants and polyelectrolytes as interfacial agents improve the stability of the nanoparticles whereas swellable and soft shell‐like cross‐linked polymeric layer at the interface can significantly enhance the uptake of guest nano‐constituents during assemblies. Besides, layer‐by‐layer surface‐functionalization holds the ability to provide a high variability in assembly architectures of different interfacial properties. Considering these aspects, various assembly architectures of polymer nanoparticles of tunable size, shapes, morphology, and tailored interfaces together with controllable interfacial interactions are constructed here. The microfluidic‐mediated platform has been used for the synthesis of constituents polymer nanoparticles of various structural and interfacial properties, and their assemblies are conducted in batch or flow conditions. The assemblies presented in this progress report is divided into three main categories: cross‐linked polymeric network's fusion‐based self‐assembly, electrostatic‐driven assemblies, and assembly formed by encapsulating smaller nanoparticles into larger microparticles.

On the Combined Effect of Both the Reinforcement and a Waste Based Interfacial Modifier on the Matrix Glass Transition in iPP/a-PP-pPBMA/Mica Composites.

This work deals with the changes of the glass transition temperature (Tg) of the polymer in polypropylene/mica composites due to the combined and synergistic effect of the reinforcement and the interfacial modifier. In our case, we studied the effect on Tg of platy mica and an interfacial modifier with p-phenylen-bis-maleamic acid (pPBMA) grafted groups onto atactic polypropylene (aPP-pPBMA). This one contains 5.0 × 10−4 g·mol−1 (15% w/w) grafted pPBMA and was previously obtained by the author’s labs by using industrial polymerization wastes (aPP). The objective of the article must be perceived as two-fold. On one hand, the determination of the changes in the glass transition temperature of the isotactic polypropylene phase (iPP) due to both the reinforcement and the agent as determined form the damp factor in DMA analysis. On the other hand, forecasting the variation of this parameter (Tg) as a function of both the interfacial agent and reinforcement content. For such purposes, and by assuming the complex character of the iPP/aPP-pPBMA/Mica system, wherein interaction between the components will define the final behaviour, a Box–Wilson experimental design considering the amount of mica particles and of interface agent as the independent variables, and the Tg as the dependent one, has been used. By taking in mind that the glass transition is a design threshold for the ultimate properties of parts based in this type of organic–inorganic hybrid materials, the final purpose of the work is the prediction and interpretation of the effect of both variables on this key parameter.

Experimental study of fracture properties of interfacial transition zone by three-point bending tests on granite-mortar hybrid beams

The three-point bending tests were performed on the granite-mortar hybrid beam specimens to investigate the fracture properties of the interfacial transition zone (ITZ). Their curves of load versus crack mouth opening displacement were obtained. The peak load ratio and the fracture energy ratio between the hybrid specimen and the mortar specimen with the same water-cement ratio in mortar were introduced to characterize the weak ITZ fracture properties. The effects of the water-cement ratio in mortar, interface roughness and silica fume content in interfacial agent on the peak load and fracture energy were investigated and their relations were also fitted approximately. The results showed that both the peak load and fracture energy can be significantly increased by reducing the water-cement ratio in mortar and by increasing the granite-mortar interface roughness. However, the silica fume content has complicated nonlinear effects on the peak load and fracture energy. The optimal silica fume content is about 6%, which makes the best bonding performance between granite and mortar.

Laboratory evaluation of an efficient low interfacial tension foaming agent for enhanced oil recovery in high temperature flue-gas foam flooding

Flue-gas foam/surfactant polymer flooding is a novel technology to enhanced oil recovery for heavy oil reservoir after hot water flooding with safety and efficiency. However, high temperature and the complex composition of flue gas greatly influence the foaming ability of the foaming agent, and weaken the plugging and profile control ability of the foam. Hence, screening suitable foam agents is of great significance. Here, a typical terpolymer of N‒methyl butenone carboxylates, alkyl phenyl sulfonates and pyrrolidone was selected as an efficient foam agent. The foaming performance and stability of the foam agent remained unchanged after 300 °C aged for 72 h in the flue gas atmosphere. Foam performance and stability tests in the simulative flue gas environment, adsorption properties of oil sands, and resistance factor evaluation were carried out. It showed good foam performance and stability, low adsorption capacity (0.77 mg/g), low interfacial tension (10−2 mN/m) and high resistance factor (>418), which indicated that the terpolymer (PNCAS) can reduce the gas channeling and increase the sweep area. The results of homogeneous and heterogeneous model experiments and microscopic mechanism suggested that foam flooding can greatly improve oil recovery while the low permeable sand-pack recovery can increase almost 42% in comparison with the conventional hot water flooding.