Surface Grafting Modification Research Articles

Preparation of amidogen-rich monolithic corn bract via surface graft modification for efficient separation of acid red from wastewater

Preparation of amidogen-rich monolithic corn bract via surface graft modification for efficient separation of acid red from wastewater

Free radical graft polymerization of hydroxyethyl methacrylate and acrylic acid on polyetherimide membrane surface via redox system to improve anti-fouling and oil resistance performance

In this paper, a new scheme of graft polymerization of acrylic acid (AA) and hydroxyethyl methacrylate (HEMA) initiated by the generation of free radicals in a redox system was used to modify the surface of polyetherimide (PEI) membranes and to improve the antifouling and oil resistance properties. Various physicochemical characterization techniques (ATR-FTIR, XPS, TG, SEM, AFM, etc.) confirmed the successful grafting of hydrophilic monomers onto the PEI membrane surface. Further, the effects of different monomer concentrations on graft density, permeation separation, contamination resistance, and mechanical properties were investigated. Both PEI-g-PAA and PEI-g-PHEMA showed better hydrophilicity (WCA decreased from 60° in PEI to 33° and 45°, respectively), efficient separation (75–84%) in oil-containing wastewater filtration tests with methyl tert-butyl ether (MTBE) and petroleum ether with a slight decrease in mechanical strength. In addition, bovine serum albumin (BSA) and MTBE were selected as contaminants to examine the antifouling properties. Compared to the flux recovery rate (FRR) of 75% for the original PEI membranes, the grafted membranes almost wholly recovered the permeate flux with a simple backwash of ultrapure water. In summary, the results of the above study suggest the development of a novel and simple preparation strategy for surface grafting modification of PEI membranes, which will facilitate the subsequent research of PEI materials in membrane development, and the resulting grafted membranes will be of developmental and exploratory value in the field of oil and water treatment.

A surface grafting strategy for antifouling/bioadhesive properties on a Janus-type polymeric thin film

There have been great technical challenges in preparation of a transparent polymeric thin film with Janus-type antifouling and bioadhesive properties on both surfaces, while maintaining the optical and mechanical characteristics of the bulk material. Herein, poly(2-hydroxyethyl methacrylate) (PHEMA), which is commonly used as an ophthalmic hydrogel, was employed as the bulk material for allowing consecutive surface grafting of functional polymer brushes, which eventually resulted in a Janus-type transparent thin film for potential biomedical implantation. First, a bromine-containing reagent served as the reactive initiator was silanized onto both surfaces of the PHEMA hydrogel thin film under a mild condition. Then, with the presence of selected physical shielding on one side using a scotch tape, polymer brushes with cell-adhesive Arg-Gly-Asp (RGD) peptide pendent groups were grafted from the other side of the PHEMA thin film, resulted in a highly improved cell attachment capability. Once the tape was removed and the RGD-modified surface was shielded, the zwitterionic polymer brushes comprising poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) segments were grafted on the surface, again through surface-initiated activators regenerated by electron transfer atom-transfer radical polymerization (SI-ARGET-ATRP). Hence, this side of the PHEMA film became super hydrophilic and exhibited antifouling properties on the surface. After the surface grafting modification, the whole PHEMA hydrogel maintained highly transparent and biocompatible for potential ophthalmic applications. This study provides a simple and rather universal strategy for fabricating Janus-type polymeric thin films with distinct biophysical/biochemical properties on both sides, which potentially applicable for the multifunctional requirements in biomedical applications.

Enhancing membrane separation performance in the conditions of different water electrical conductivity and fouling types via surface grafting modification of a nanofiltration membrane, NF90

A commercialized and widely applied nanofiltration membrane, NF90, was in-situ modified through a surface grafting modification method by using 3-sulfopropyl methacrylate potassium salt and initiators. The effects of water electrical conductivity (EC) and fouling types on membrane separation efficiency were examined before and after membrane modification. Results reveal that both the pristine membrane (PTM) and surface grafting modification membrane (SGMM) had a declining permeate flux and salt (NaCl) removal efficiency but an increasing trend of pharmaceuticals and personal care products (PPCPs) removal with increasing water EC from 250 to 10,000 μs cm−1. However, SGMM exhibited a slightly declining permeate flux but 13%–17% and 1%–42% higher rejection of salt and PPCPs, respectively, compared with PTM, due to electrostatic repulsion and size exclusion provided by the grafted polymer. After sodium alginate (SA) and humic acid (HA) fouling, SGMM had 17%–26% and 16%–32% higher salt rejection and 1%–12% and 1%–51% greater PPCP removal, respectively, compared with PTM due to the additional steric barrier layer contributed by the foulants. The successful grafting and increasing hydrophilicity of the SGMM were confirmed by contact angle analysis, which was beneficial for mitigating membrane fouling. Overall, the proposed in-situ surface grafting modification of NF90 can considerably mitigate organic and biological fouling while raising the rejection of salt and PPCPs at different background water EC, which is beneficial for practical applications in producing clean and high quality water for consumers.

Study on Modification Technology of Superfine Dry Powder Fire Extinguishing Agent

The superfine dry powder fire extinguishing agent has the characteristics of high fire extinguishing efficiency and low cost and has been widely used in the field of fire extinguishing. This paper briefly describes the classification and current problems of dry powder and analyzes the current technology of micronization and surface modification. The superfine dry powder fire extinguishing agent is greatly improved in water resistance by surface grafting modification, the water repellency meets the standard requirements, and the D90 particle size of the dry powder extinguishing agent after modification is ≤15μm.

Synergetic impact of both fiber surface grafting and matrix modification by carbon nanotubes and functionalized carbon nanotubes on the flexural behavior of carbon fiber reinforced polymer composites: An assessment at cryo‐, room‐, and elevated‐ in situ temperature conditions

AbstractIn this article, the carbon fiber reinforced vinyl ester (CVE) composite was modified with pristine and functionalized carbon nanotubes (CNTs/FCNTs) using the in situ polymerization and electrophoretic deposition (EPD) techniques: individually and using both simultaneously. Their influence on the flexural properties of the composites at room (RT), cryogenic (−196°C) (CT), and elevated (70°C) (ET) temperatures were compared. Through matrix modification, the best flexural strength with CNT and FCNT modified composites was found to be 6.2% and 9.9% higher over neat CVE composite. Similarly, following the EPD technique, the optimum flexural strength enhancement with CNT and FCNT was recorded to be 10.3% and 13.8% with respect to the control composite respectively. A synergetic impact could be noticed by combining both the techniques together, where the flexural strength of the hierarchical composite with FCNT modification was improved by ~22%, ~25%, and ~ 6% higher than that of control CVE at RT, CT and ET respectively. The dispersion quality of nanotubes in the matrix and on the carbon fiber surface, and fractured surface morphology is analyzed using a SEM.

Green and stable lignin-based nanofillers reinforced poly(l-lactide) with supertough and strong performance

Lignin nanoparticles (LNPs), as a new type of green nanomaterial, initiate many promising applications in polymer composites. However, their heterogeneity, dissolution in organic solvents, and poor compatibility in the polymer matrix greatly limited the applications of LNPs fillers. Herein, we proposed an antisolvent precipitation of the fractionations by combining a hydrothermal treatment-assisted synthesis to fabricate self-crosslinked LNPs (ScLNPs), which have good stability in the organic solvent and controllable sizes. After surface grafting modification with d-lactide, ScLNPs-graft-poly(d-lactide) (ScLNPs-g-PDLA) exhibited excellent dispersion and compatibility in PLLA matrix. Using the rational design and addition of ScLNPs-g-PDLA fillers, the strength and toughness of the generated PLLA composite reached 31.6 MPa and 396 % (the highest value among the PLLA materials), respectively. Furthermore, the mechanical performance can also be well-tuned by the sizes and amounts of LNPs fillers. This strategy involving only green and recyclable materials provides an effective route to producing sustainable polymeric plastics with integrated strength and super-toughness.

Fabrication of a Modified Polyethersulfone Membrane with Anti-Fouling and Self-Cleaning Properties from SiO2-g-PHEMA NPs for Application in Oil/Water Separation

To prepare anti-fouling and self-cleaning membrane material, a physical blending modification combined with surface grafting modification has been carried out; first, poly (2-hydroxyethyl methacrylate) grafted silica nanoparticles (SiO2-g-PHEMA NPs) were synthesized using surface-initiated activators regenerated by electron transfer atom transfer radical polymerization (ARGET ATRP) and used as a blending modifier to fabricate a polyethersulfone (PES)/SiO2-g-PHEMA organic–inorganic membrane by the phase-inversion method. During the membrane formation process, hydrophobic PES segments coagulated immediately to form a membrane matrix, and the hydrophilic SiO2-g-PHEMA NPs migrated spontaneously to the membrane surface in order to reduce interfacial energy, which enhanced the hydrophilicity and anti-fouling properties of the PES/SiO2-g-PHEMA membrane. Importantly, the membrane surface contained abundant PHEMA segments, which provided active sites for further surface functionalization. Subsequently, the carboxyl-terminated fluorocarbon surfactant (fPEG-COOH) composed of hydrophilic polyethyleneglycol segments and low-surface-energy perfluorinated alkyl segments was synthesized via the esterification of fPEG with succinic anhydride. Lastly, the PES/SiO2-g-PHEMA/fPEG membrane was prepared by grafting fPEG-COOH onto surface of the PES/SiO2-g-PHEMA. Thus, a versatile membrane surface with both fouling-resistant and fouling-release properties was acquired. The PES/SiO2-g-PHEMA/fPEG membrane has a large oil–water flux (239.93 L·m−2·h−1), almost 21 times that of PES blank membrane and 2.8 times of the PES/SiO2-g-PHEMA membrane. Compared with the unmodified PES membrane, the flux recovery ratio increased from 45.75% to 90.52%, while the total flux decline ratio decreased drastically from 82.70% to 13.79%, exhibiting outstanding anti-fouling and self-cleaning properties. Moreover, the grafted fPEG segments on the membrane surface show excellent stability due to the presence of stable chemical bonds. The grafted segments remain at the surface of the membrane even after a long shaking treatment. This suggests that this PES/SiO2-g-PHEMA/fPEG membrane material has potential for application in oil/water separation.

3D printed 0–3 type piezoelectric composites with high voltage sensitivity

Piezoelectric composites made of piezoelectric ceramic particles and polymer composites combine the performance advantages of both components and have broad application prospects. However, the preparation of complex structures is still a challenge, for which 3D printing technology provides a perfect solution. The aim of the present study is to investigate the principle and process optimization of the stereolithography of 0–3 type piezoelectric composites through simulation and experiments. In particular, a modified three-phase model of a spherical shell is applied to elucidate the influence of the elastic modulus between the ceramic particles and the matrix on the piezoelectric properties of the composites at the macroscopic level. This enables the piezoelectric properties of the composites to be predicted more accurately, and guides the surface grafting modification of piezoelectric ceramic powders. Furthermore, the problem of weak interface bonding in piezoelectric composites caused by poor compatibility between hydrophilic particles and the hydrophobic matrix is successfully solved by preprocessing the PZT ceramic powder via activating the particle surface hydroxyl groups and grafting a silane coupling agent onto the piezoelectric ceramic powder. As a result, the particles are bonded to the matrix by covalent bonds, which increases the elastic modulus of the interface transition layer and modifies the stress transfer efficiency. For instance, the piezoelectric strain constant (d33) of piezoelectric composite containing 60 wt% functionalized PZT particles is increased from 20 to 37 pC/N. The printing accuracy, piezoelectric properties, and mechanical characteristics of the piezoelectric composites are thoroughly investigated, and the reliability of the proposed theoretical model and simulation results is verified. The piezoelectric composites are uniformly compact and have a low residual pore rate. The piezoelectric composite with a solid content of 60 wt% has a volume density of 2.27 g/cm3 and a Young's modulus of 535.44 MPa. Most importantly, its piezoelectric voltage constant (g33) is 167.2 × 10−3 Vm/N, which is more than seven times higher than that of homogeneous PZT and results in high voltage sensitivity.

Research of a modified nano-depressure and augmented injection agent

In this paper, the research and application of nanomaterials in oilfield chemical engineering was briefly described with emphasis on the nano-silica in enhanced oil recovery, depressure and augmented injection. A study on the modification of nano-silica was carried out indoors, and a modified nano-depressure and augmented injection agent was prepared by using a coupling agent for surface grafting modification, followed by introducing functional monomers for in-situ modification. The effects of silica dosage, coupling agent dosage, dispersant and regulator ratio, and modification time on the modified product were investigated. It was analyzed by infrared spectroscopy, thermogravimetric analysis, nanoparticle size analyzer, transmission electron microscope, atomic force microscope, etc. A series of experiments were conducted to evaluate the temperature and salt resistance, wettability, as well as depressure and augmented injection performance of the modified products.

ADVANCES IN TECHNIQUES AND APPLICATIONS OF RUBBER SURFACE GRAFTING MODIFICATION

ABSTRACT To meet the requirement in the application of medical devices, composites, biomaterials, corrosion resistance, and selective adsorptions, rubber surface modification is usually indispensable. Grafting treatment is one of most significate treatment methods. In this paper, we focus on rubber surface grafting modification, including grafting techniques and applications. Different grafting methods—including monomer grafting polymerization and coupling reaction—are covered and compared briefly. The related applications of surface grafting modification techniques, such as improving compatibility of waste rubber as fillers, hydrophobicity and lipophilicity of sponge rubber for oil–water separation, biocompatibility of rubber in the medical field, and forming surface patterns, are demonstrated in detail. The new research directions of surface grafting techniques as well as main challenges in application are also discussed.

Surface Graft Modification of Domestic PBO Fiber by Atmospheric Air Plasma

Surface Graft Modification of Domestic PBO Fiber by Atmospheric Air Plasma

A combined physical blending and surface grafting strategy for hydrophilic modification of polyethersulfone membrane toward oil/water separation

The block copolymer, Pluronic F127-block-poly(acrylic acid) (PAA-b-F127-b-PAA) was firstly synthesized via RAFT polymerization. Then, the copolymer was utilized as the blending modifier for fabricate polyethersulfone (PES)/PAA-b-F127-b-PAA composite membrane by nonsolvent induced phase separation technique. The hydrophilic PAA segments were concentrated onto the membrane surface due to the surface segregation phenomenon in the membrane formation process, which improved the hydrophilicity of the membrane surface and provided active sites for further surface grafting modification. Subsequently, the amine-terminated poly(sulfobetaine methacrylate) (NH2-PSBMA) was prepared through ARGET ATRP and used as surface modifier to fabricate PES/PAA-b-F127-b-PAA/PSBMA composite membrane by amination reaction. The composite membrane exhibited the highest pure water flux and oil flux around 358.25 and 217.53 L m−2 h−1, which equal to 5.6 times and 19.6 times of unmodified PES membrane respectively. The flux recovery rate increased from 45.74% to 94.64%, suggesting the fouling-resistance of the composite membranes was greatly improved. The hydrophobic PPO segments of PAA-b-F127-b-PAA used as anchor segments and amalgamated with PES molecular by hydrophobic interaction and physical intertwisting, resulting in the PAA-b-F127-b-PAA was firmly embedded in the membrane. Moreover, the PSBMA segments were grafted onto the membrane surface by forming strong chemical bonds, exhibiting excellent stability. It shows that this membrane material prepared by physical blending and surface grafting has a good application prospect in oil/water separation.

Synthesis and characterization of dicyclic silicon‐/phosphorus‐grafted alumina and its application in improving flame retardancy of epoxy resin

AbstractA new phosphorous/silicon/aluminum hybrid flame retardant (SAlu) was prepared by a surface grafting modification of alumina with a polymer (SDPS). The polymer was prepared by a condensation reaction between 3,9‐dichloro‐2,4,8,10‐tetrahydroxy‐3,9‐diphosphate heterocyclic‐3,9‐dioxide [5.5] undecane (SPDPC) and diphenyldisiloxol. The structure of the SAlu was further characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, UV–Vis absorption, and particle size analysis. Thermogravimetric analysis showed that SPDS was grafted over 40% of the alumina surface. When introduced into epoxy resin, SAlu effectively improved the thermal stability and carbonization rate of the epoxy composites at high temperature. Carbonization studies showed that SAlu promoted formation of a ceramic‐carbon coking structure with a porous morphology of aggregates, which isolate combustible materials, heat, and oxygen. These features improved the flame retardant performance of the composite. The solidified materials were evenly dispersed in the network structure to improve the elastic deformation ability and glass transition temperature of the solidified resin.

Functionalized cellulose nanocrystals as the performance regulators of poly(β-hydroxybutyrate-co-valerate) biocomposites

To investigate the relationship between functional groups on cellulose nanocrystals (CNC) and the performance of poly(β-hydroxybutyrate-co-valerate) (PHBV), the surface of CNC was modified by surface graft modification and PHBV/CNC biocomposites were prepared by melt blending. To demonstrate the interfacial adhesion difference between hydrophobic PHBV and hydrophilic CNC, palmitoyl chloride and ε-caprolactone had been used to tailor the oleophilic property of CNC. Results showed that CNC had heterogeneous nucleation effect on the crystallization process of PHBV, while the entanglement of molecular chains weakened the promoting functions of CNC-g-C16 (CNC grafted with palmitoyl chloride) and CNC-g-CL (CNC grafted with ε-caprolactone). Furthermore, CNC-g-CL exhibited better interfacial adhesion with PHBV when compared with CNC-g-C16. And 1 wt% CNC-g-CL improved the tensile strength of PHBV biocomposite to 38.09 MPa, which is 26.25% higher than PHBV.

Improving the hydrophilicity of polyethersulfone membrane by the combination of grafting technology and reverse thermally induced phase separation method

AbstractIn this work, surface grafting modification technology was combined with reverse thermally induced phase separation (RTIPS) method in order to improve the structure and permanent hydrophilicity of polyethersulfone (PES) membranes. Acrylic solution with different concentrations was grafted on the surface of PES membranes while grafting temperature and grafting time were also varied. The modified PES membranes were characterized in all aspects. Attenuated total reflectance Fourier transform‐infrared confirmed successful modification of the PES membrane by grafting acrylic acid. Scanning electron microscopy revealed that homogeneous porous top surface as well as spongy‐like cross‐section structure appeared in the membrane by RTIPS procedure. Moreover, porosity was affected by changes of acrylic acid concentration, grafting temperature, and grafting time. Atomic force microscopy showed that grafting acrylic acid gave a reduction in roughness of PES membrane. Combined with the decreased values of contact angle, the hydrophilicity and antifouling performance of the PES membrane were improved. The pure water flux and BSA rejection rate of the grafted PES membranes were remarkably improved for pure PES membrane and attained a maximum, which was 1,646.24 L/(m2h) and 94.5%, respectively. The long‐term test demonstrated that grafting membranes exhibited outstanding elevated water flux recovery ratio (>85%).

WITHDRAWN: MXene surface grafting modification and the application for organic solvent nanofiltration membrane

WITHDRAWN: MXene surface grafting modification and the application for organic solvent nanofiltration membrane

SrTiO3 as a new solar reflective pigment on the cooling property of PMMA-ceramic composites

Abstract Polymer-ceramic hybridization is an important method for preparing functional materials. Strontium titanate (SrTiO3, ST), a typical perovskite ceramic, has been widely applied in the electronics industry and photocatalytic fields. However, ST was barely reported to be utilized in cool materials. Herein, ST ceramic, as a solar reflective pigment, was introduced into a polymer matrix to prepare cool material. Specifically, the influences of both weight contents and surface grafting modification about ST on the properties of poly(methyl methacrylate) (PMMA)/ST composites were investigated, which include cooling performance, surface roughness, thermal emissivity, dispersion of particles and mechanical strength. The obtained composites containing 20 wt% unmodified ST possess excellent cooling property due to high thermal emissivity (86.8%, in 8–13 μm) and high solar reflectance (70.7%, in the whole solar band) which increased by 142% than that of pure PMMA resin. Temperature test highlighted that the composites containing 20 wt% unmodified ST was only 26.6 °C, 11.4 °C lower than that of PMMA resin and only 2 °C higher than initial temperature. Moreover, the surface grafting modification of ST by the silane coupling agent was proved to improve the dispersibility of ST in PMMA resin. Both the cooling and mechanical properties of composites containing modified ST particles were further improved. Though the solar reflectance of PMMA/ST composites was lower than that of PMMA/TiO2 composites, temperature tests showed that the PMMA/ST composites had a similar cooling performance with the PMMA/TiO2 composites when the content of the ceramic particles were 5.8 v%. This work not only prepared the polymer-ceramic hybrid materials with excellent cooling performance but also expanded the application of ST ceramic in the field of composites.

Surface grafting modification of titanium dioxide by silane coupler KH570 and its influences on the application of blue light curing ink

A series of reactive TiO2 pigments with olefinic double-bonds were prepared by grafting modification of silane coupler KH570 to be covalently anchored in the blue-light curing film, which improved the color fastness to crocking of the printed fabrics significantly. Effects of KH570 concentrations on particle size, surface wettability and dispersing stability of KH570-TiO2 pigments, photo-polymerization of KH570-TiO2 bule-light curing inks and tensile properties of curing films were investigated. Color fastness to crocking of KH570-TiO2 pigment on cotton fabric was explored. Results showed that compared to the native TiO2, all the properties of KH570-TiO2 improved. With the increases of KH570 concentrations, the grafting degrees of KH570-TiO2 had gradual increase. The surface hydrophobicity and dispersion stability of KH570-TiO2 pigments, photo-polymerization of KH570-TiO2 blue-light curing ink and tensile properties of curing films enhanced, especially those of 12∼20KH570-TiO2 the best. Within the concentrations of KH570 12–20 wt %, the printed fabrics had dry/wet color fastness to crocking no less than 4 grades.

Advances in the hyperbranched and poly amidoamine dendrimers grafting modification methods of chromatographic stationary phase

With the rapid development of chromatographic stationary-phase preparation technology, various modified methods are becoming increasingly mature, mainly including direct surface chemical reactions, agglomeration, grafting, and hyperbranched modification. Among these methods, hyperbranched modification based on polycondensation has been popular with researchers since it was proposed, and it has been applied to the preparation of various anion exchangers. Dendrimers are a class of three-dimensional, highly ordered dendritic macromolecules with perfect structure, high degree of surface functionality, and unique physicochemical properties. Recently, they have also gradually been applied in various chromatographic stationary-phase modifications and are expected to improve the structure and separation performance of the stationary phase, because its structure is similar to those of hyperbranched polymers. This article mainly summarizes the applications of hyperbranched and poly amidoamine dendrimers using grafted modification methods in the preparation of the chromatographic stationary phase. Finally, the trends and promising prospects of this field are presented.