Free Radical Polymerization Process Research Articles

An orthogonal approach for the synthesis of graft copolymers: Visible light induced free radical polymerization and iniferter processes

Graft copolymers with polystyrene main and poly(ethylene glycol) methyl ether acrylate side chains are synthesized via an orthogonal approach combining visible light induced free radical polymerization and iniferter processes. The method relies on a deliberately designed, double functional monomer, 2,2,2-(triphenylethyl)styrene (TPES), containing both polymerizable and iniferter units.

Ultrafast Sunlight-Induced Polymerization: Unveiling 2-Phenylnaphtho[2,3-d]Thiazole-4,9-dione as a Unique Scaffold for High-Speed and Precision 3D Printing.

A series of 15 dyes based on the 2-phenylnaphtho[2,3-d]thiazole-4,9-dione scaffold and 1 compound based on the 2,3-diphenyl-1,2,3,4-tetrahydrobenzo[g]quinoxaline-5,10-dione scaffold are studied as photoinitiators. These compounds are used in two- and three-component high-performance photoinitiating systems for the free radical polymerization of trimethylolpropane triacrylate (TMPTA) and polyethylene glycol diacrylate (PEGDA) under sunlight. Remarkably, the conversion of TMPTA can reach ≈60% within 20s, while PEGDA attains a 96% conversion within 90s. To delve into the intricate chemical mechanisms governing the polymerization, an array of analytical techniques is employed. Specifically, UV-vis absorption and fluorescence spectroscopy, steady-state photolysis, stability experiments, fluorescence quenching experiments, cyclic voltammetry, and electron spin resonance spin trapping (ESR-ST) experiments, collectively contribute to a comprehensive understanding of the photochemical mechanisms. Photoinitiation capacities of these systems are determined using real-time Fourier transformed infrared spectroscopy (RT-FTIR). Of particular interest is the revelation that, owing to the superior initiation ability of these dyes, high-resolution 3D patterns can be manufactured by direct laser write (DLW) technology and 3D printing. This underscores the efficient initiation of free radical polymerization processes by the newly developed dyes under both artificial and natural light sources, presenting an avenue for energy-saving, and environmentally friendly polymerization conditions.

Designing magnetic catalysts based on gold nanoparticles supported by ethylenediamine tetraacetic acid functionalized amino‐modified poly(N‐isopropyl acrylamide) for reduction of nitro compounds in water

AbstractA novel smart catalyst was developed with amino‐modified thermo‐responsive poly(N‐isopropyl acrylamide) (PNIPAM) grafts on silica‐coated magnetic nanoparticles using the conventional free radical polymerization process. By this methodology, the polymer was successfully grafted mainly onto silica‐modified iron oxide nanoparticles (Fe3O4@Si). The PNIPAM‐grafted Fe3O4@Si was then subjected to ethylenediamine treatment to produce the amino‐functionalized support (Fe3O4@Si@PNIPAM‐NH2), which was subsequently modified with carboxyl functional groups by using EDTA (ethylenediaminetetraacetic acid) to create Fe3O4@Si@PNIPAM‐NH2‐EDTA. Au nanoparticles were then decorated on this support through its two amines and four carboxylates. Different methods were used to study this novel catalyst, including inductively coupled plasma, Fourier transport infrared spectroscopy, TGA, dynamic light scattering, SEM, energy‐dispersive X‐ray analysis, vibrating sample magnetometry, XRD and elemental CHN analysis. The reduction of several aryl‐nitro derivatives demonstrated a significant catalytic activity for the as‐synthesized gold catalyst (Fe3O4@Si@PNIPAM‐NH2‐EDTA‐Au). The Au catalyst can be successfully removed from the reaction components using a magnetic field and used again in eight successive reduction reactions without significant gold leaching and loss of catalytic activity. © 2024 Society of Industrial Chemistry.

Structured polymer dispersant for efficient phthalocyanine blue dispersion and color paste preparation

AbstractTo overcome challenges in pigment dispersion, especially for difficult‐to‐disperse pigments like phthalocyanine blue, the structure of dispersants has been studied in recent years. Herein, we present the development and performance evaluation of a structured polymer dispersant for efficient dispersion of phthalocyanine blue and color paste preparation. The dispersant was synthesized using a two‐step free radical polymerization process, allowing precise control over its structure. The study investigates the impact of key factors on dispersion, including the molecular weight of the hydrophilic long‐chain poly(ethylene glycol) monomethyl ether (MPEG), the ratio of anchoring groups styrene (St) and dimethylaminoethyl methacrylate (DMAEMA), and the dispersant dosage. Optimal stability was achieved with MPEG‐400 as the hydrophilic long chain and a St:DMAEMA ratio of 1:1, along with a MPEG‐400AA:AA ratio of 0.5:1 at 2000 r min−1. At a dispersant dosage of 25%, the particle size of the color paste measured 340 nm, with viscosity reaching 600 mPa·s. The structured dispersant effectively synergized spatial potential resistance and electrostatic effects to achieve stable pigment dispersion. These findings offer promising prospects for advancing dispersant technologies, with implications for improving color‐based applications across various industries, such as paints, coatings, and inks.

Dextrin‐graft‐poly(2‐dimethylamino ethyl acrylate‐co‐2‐acrylamido‐2‐methyl propane sulfonic acid) polymer: A potential adsorbent for the fast removal of nitrophenols from aqueous medium

AbstractA graft copolymer is synthesized by grafting a mixture of 2‐(dimethylamino) ethyl acrylate (DMAEA) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) monomers onto the dextrin, polysaccharide backbone via free radical polymerization process using potassium peroxydisulfate (KPS) as radical initiator in aqueous phase. Various characterization techniques like 1H and 13C NMR, FT‐IR, SEM, EDAX, and XRD analysis are used to characterize the copolymer. The polymer is used as an adsorbent for the removal of nitrophenols namely ortho‐nitrophenol (ONP), para‐nitrophenol (PNP), and 2,4‐ dinitrophenol (DNP) from their water solutions. Adsorption dynamics, kinetics, isotherms, and thermodynamics are studied. The maximum nitrophenol adsorption occurs at time 80 min, temperature 45°C, pH 3.5 (DNP), and 4.5 (ONP and PNP), polymer dose 30 mg/L. The nitrophenol adsorption data are well‐fitted with the Langmuir isotherm model with maximum adsorption capacity () 215.26 mg g−1 for ONP, 223.60 mg g−1 for PNP, and 288.24 mg g−1 for DNP. The equilibrium kinetics follow pseudo‐second‐order kinetic model. Thermodynamic values unfold that the following nitrophenol adsorption onto the polymer surface is spontaneous and endothermic in nature. The value of Gibb's free energy for the nitrophenol adsorption is in the range of −6.5 to −9.5 kJ mol−1. The preferential nitrophenol adsorption by the copolymer is followed in the order ONP<PNP<DNP.

Synthesis, Characterization, Optical and Thermal Properties of P(NVC-co-BZMA) Copolymer and Its ZnO Composites

Recent studies have paid particular attention to polymer-nanoparticle composite materials considering they have a number of interesting properties, which include optical, thermal, electrical, and others (Reyna-Gonzalez et al., 2009; Yakuphanoglu et al., 2010). In this study, a free radical polymerization process was used to create a copolymer of N-vinylcarbazole (NVC) and benzyl methacrylate (BZMA) at 25–75 mol% each. The procedure was conducted at 70°C with azobisisobutyronitrile (AIBN) acting as the initiator. Nano zinc oxide powders were then added to composites at three different ratios of 5%, 10%, and 15% weight of the copolymer. In order to better understand the structures of the P(NVC-co-BZMA) and its composites, FT-IR, 1H NMR, and UV spectroscopic techniques were also implemented. The optical characteristics of both the pure copolymer and its composites were examined. In the visible region, the composite containing 15% nano ZnO had the highest optical absorbance value. Additionally, the thermal behaviours of the composites and copolymers were analysed.

Spectroscopic investigations of solvent assisted Li-ion transport decoupled from polymer in a gel polymer electrolyte

We present here a gel polymer electrolyte, where the Li+-ion transport is completely decoupled from the polymer host solvation and dynamics. A free-standing gel polymer electrolyte with a high volume content (nearly 60%) of xM LiTFSI in G4 (tetraglyme) (x = 1–7; Li+:G4 = 0.2–1.5) liquid electrolyte confined inside the PAN (polyacrylonitrile)-PEGMEMA [poly (ethylene glycol) methyl ether methacrylate oligomer] based polymer matrix is synthesized using a one-pot free radical polymerization process. For LiTFSI concentrations, x = 1–7 (Li+:G4 = 0.2–1.5), Raman and vibrational spectroscopies reveal that like in the liquid electrolyte, the designed gel polymer electrolytes (GPEs) also show direct coordination of Li+-ions with the tetraglyme leading to the formation of [Li(G4)]+. Coupled with the spectroscopic studies, impedance and nuclear magnetic resonance investigations also show that the ion transport is independent of the polymer segmental motion and is governed by the solvated species {[Li(G4)]+}, very similar to the scenario in ionic liquids. As a result, the magnitude of ionic conductivity and activation energies of the gel polymer electrolyte are very similar to that of the liquid electrolyte. The Li+-ion transport number for the GPE varied from 0.44 (x = 1) to 0.5 (x = 7) with the maximum being 0.52 at x = 5.

Temperature Controlled Mechanical Reinforcement of Polyacrylate Films Containing Nematic Liquid Crystals.

This investigation reports on the thermomechanical properties of Poly-tripropyleneglycoldiacrylate (Poly-TPGDA)/liquid crystal (LC) blends, developed via free radical polymerization processes, which are induced by Electron Beam (EB) and Ultraviolet (UV) radiation. The EB-cured Poly-TPGDA network exhibits a higher glass transition temperature (Tg), a higher tensile storage, and Young moduli than the corresponding UV-cured sample, indicating a lower elasticity and a shorter distance between the two adjacent crosslinking points. Above Tg of Poly-TPGDA/LC blends, the LC behaves as a plasticizing agent, whereas, for EB-cured networks, at temperatures below Tg, the LC shows a strong temperature dependence on the storage tensile modulus: the LC reinforces the polymer due to the presence of nano-sized phase separated glassy LC domains, confirmed by electron microscopy observations. In the case of the UV-cured TPGDA/LC system, the plasticizing effect of the LC remains dominant in both the whole composition and the temperature ranges explored. The rubber elasticity and Tg of Poly-TPGDA/LC films were investigated using mechanical measurements.

Environmentally adaptable hydrogel electrolyte with the triple interpenetrating network in the flexible zinc-ion battery with ultralong stability

With the increasing development of wearable electronic devices, the stabilities of the flexible battery are in great demand. However, the rapid capacity degradation and the limits of the traditional aqueous electrolyte in cold environmental condition still retards the practical application of the aqueous zinc ion batteries (ZIBs). Herein, a polyacrylamide/carboxymethyl cellulose/gelatin (PCG) hydrogel electrolyte with triple interpenetrating network was fabricated by an integrated physical crosslinking and free-radical polymerization process. Benefitting from its hierarchical porous structure, the PCG hydrogel electrolyte exhibits the stable mechanical compression deformation. The integrated cross-linked networks with abundant hydrogen bonds and high electrolyte salt prevent the crystallization of water, contributing to broadening its operating temperature (from −20 °C to room temperature). Therefore, the PCG electrolyte cannot only promise the highly reversible Zn2+ insertion/extraction, but also accelerate ion transfer in electrochemical process. As a result, the PCG-based ZIBs with magnesium vanadium oxide deliver a high capacity of 382.7 mAh g−1 and good cycling stability (10000 cycles at 0 °C). Besides, the assembled flexible ZIBs also exhibit a good capacity retention under various bending states. This unique strategy of hydrogel electrolyte provides new insights for flexible ZIBs with superior cycling stability.

Highly Stretchable, Tough, and Self-Recoverable Cationic Guar Gum-Based Hydrogels for Flexible Sensors

Stretchable and tough conductive hydrogels have attracted much attention in flexible sensing electronics. However, most existing conductive hydrogels have poor strain and strength or unsatisfactory recovery capability, which cannot satisfy the requirements for stretchable electronics. In this study, a type of hybrid ionic-covalent guar hydroxypropyltrimonium chloride (cationic guar gum, CGG)-based DN hydrogel with PAM covalent and CGG-CO32– or CGG-SO42– ionic networks via a free radical polymerization and soaking process was developed to prepare high-performance strain sensors. The existence of salt ions in the CGG-based hydrogel not only induces the formation of noncovalent cross-linking points, endowing the hydrogel high mechanical performance, but also gives the hydrogel high ionic conductivity. Consequently, the obtained hybrid DN hydrogels show high tensile strength (>1.2 MPa), large elongation (>1200%), high toughness, good conductivity, and rapid self-recovery property. Significantly, by simply controlling the soaking duration, we tailored the mechanics of the hybrid DN hydrogels. As demonstrated, this hydrogel-based sensor exhibits good sensitivity, large strain sensing capability, high durability, and could detect various human motions. Our study opens up a horizon in the preparation and regulation of cationic guar gum-based hydrogels for applications in high-performance flexible sensors.

Molecular imprinted polymer for tramadol: Absorption and drug release studies

AbstractSmart polymeric matrices based on 2‐vinyl pyridine (2‐VPY) and three different crosslinkers: ethylene glycol dimethacrylate (EGDMA), divinylbenzene (DVB), and trimethylolpropane trimethacrylate (TMPTMA) were prepared either by the imprinting technique of the tramadol molecule or conventionally by the free radical polymerization process. The polymers were used as sorbent materials for tramadol from its solutions. The polymers prepared by the imprinting technique demonstrated superior absorption of tramadol molecules than those prepared by the conventional method. The two sorbent materials constructed from TMPTMA, regardless of the method, achieved the highest absorption capacity compared with those prepared from EGDMA or DVB. It was found that loaded imprinted polymer released more tramadol than loaded nonimprinted polymer in all media. In the acidic medium, the protonation of the nitrogen atom in the pyridine ring ionized the chains and expanded the loaded pores leading to the rapid release over the neutral and alkaline media. Additionally, the isothermal studies of MIP3 and NIP3 were extremely fitted to Freundlich adsorption and the (D–R) isotherm, respectively, while the kinetic studies of both sorbents were fitted to the pseudo‐second‐order model.

Polyethylene glycol-based phase change materials with high photothermal conversion efficiency and shape stability in an aqueous environment for solar water heater

The development of composite phase change materials (PCM) with high photothermal conversion capability can effectively improve solar energy utilization. However, composite PCM loses the ability to encapsulate PCM in an aqueous/oil phase environment, limiting the practical scope of PCM applications. In our work, the composites stabilized in the aqueous phase were prepared using a free radical polymerization process. Composites have a high loading rate (85.1–89.0 wt%), high thermal conductivity (204% higher than PEG), high energy storage density (138.6 J/g), and high photothermal conversion efficiency (93.3%). Since PEG is encapsulated inside the structure during the polymerization of PAAAM, it can still encapsulate PEG even in the aqueous phase. Utilizing the heat storage characteristics of PEG and the high photothermal conversion characteristics of RHTC, composites can be used in solar water heater systems, reducing the operating costs and showing great application potential in aqueous phase environment.

Synthesis of a hydrophobic association polymer with an inner salt structure for fracture fluid with ultra-high-salinity water

This study used a compound initiation free radical polymerization process to synthesize a hydrophobic association polymer (PDMA1) with good salt resistance for use in ultra-high salinity reservoirs. The critical association and entanglement concentrations of PDMA1 in deionized (DI) water were 1596 and 2799 mg/L, respectively. The properties of the polymer in simulated formation (SF) water were investigated using viscosity change and conductivity tests, and the apparent viscosity of the PDMA1 solution was investigated using apparent viscosity, viscoelasticity, and thixotropy experiments. To a certain extent, the apparent viscosity of the solution was found to be influenced by metal ions. Under total dissolved solids (TDS) concentrations of up to 239,500 ppm, when the polymer concentration exceeded the critical entanglement concentration, the apparent viscosity of the polymer remained close to that of DI water. Additionally, the viscosity of the PDMA1 solution was affected by different types of metal ions, and the polymer solution thickened owing to divalent cations. PDMA1 is resistant to salt owing to hydrophobic interaction, electrostatic shielding, and double-layer compression. The results of the thixotropy and viscoelasticity tests revealed the thixotropy loop area of the PDMA1 solution in SF water to be greater than that in DI water. Under these conditions, PDMA1 is mostly viscous at low shear frequencies and mostly elastic at high shear frequencies. The PDMA1 inner-salt hydrophobic association polymer can be utilized as a chemical agent for tertiary recovery and fracturing, processes in high-salinity reservoirs, particularly for aggravating fracturing fluid.

Harnessing light to create functional, three-dimensional polymeric materials: multitasking initiation systems as the critical key to success

Nowadays, the lack of suitable photoinitiators (PI) and photoinitiating systems (PISs) represents the utmost challenge in 3D-VAT printing. High photoinitiating efficiency is needed for example in the presence of nanofillers such as carbon nanotubes (CNTs) which absorb and scatter light. Many prominent PISs contains iodonium salt as an initiator and a second component as a photosensitizer. This study addresses the high demand for innovative PISs with improved photoinitiating efficiency by a complete cycle of research: from the synthesis of new biphenyl derivatives, through their employment as photosensitizers of iodonium salt for light-induced cationic, free-radical, and hybrid polymerization processes, to the representative application in 3D printing processes such as digital light processing (DLP) or laser printing. The ultimate performance of the newly synthetized compounds was tested by preparing 3D-printable photosensitive nanocomposite resins filled with CNTs as a nanoscale filler. Their photopolymerization kinetics as well as the effect of the CNT concentration on the crosslinking were analyzed via real-time FTIR and photo-rheology. The printouts were observed with optical microscopy and scanning electron microscopy. In addition, the key printing parameters were determined, i.e. Ec (critical energy to initiate polymerization) and Dp (penetration depth of curing light). Our results evidence the capability of the synthetized compounds to take part in the photoinitiating systems of complex and demanding 3D printing applications.

Mussel-inspired self-adhesive hydrogels by conducting free radical polymerization in both aqueous phase and micelle phase and their applications in flexible sensors

Polydopamine (PDA)-based self-adhesive hydrogel sensors are extensively explored but it is still a challenge to construct PDA-based hydrogels by free radical polymerization. Herein, a new approach to construct self-adhesive hydrogels by conducting free radical polymerization in both aqueous phase and micelle phase is developed. The following two-phase polymerization processes account for the formation of the self-adhesive hydrogels. The first one is the polymerization of acrylamide (AM) and dopamine (DA) in aqueous phase to form adhesive component PAM-PDA (PAM, polyacrylamide; PDA, polydopamine). The second one is the polymerization of hydrophobic monomer 2-methoxyethyl acrylate (MEA) in micelles of an amphiphilic block copolymer Pluronic F127 diacrylate (F127DA). The poly(2-methoxyethyl acrylate) (PMEA) networks help to maintain the high robustness of the hydrogel. Because PMEA and PDA form in relatively separated phases, the inhibition effect of PDA on the free radical polymerization process of PMEA is weakened. Based on this mechanism, mechanically strong and adhesive hydrogels are achieved. The introduced ions during preparation process, such as Na+, OH– and K+, endow the resulting hydrogels ionic conductivity. Resistive strain sensor of the hydrogel achieves a high gauge factor (GF) of 5.26, a response time of 0.25 s and high sensing stability. Because of the adhesiveness, such hydrogel sensor can be applied as wearable sensors in monitoring various human motions. To further address the freezing and drying problems of the hydrogels, organohydrogels are constructed in glycerol-water mixed solvent. The organohydrogels exhibit outstanding anti-freezing property and moisture retention ability, and their adhesiveness is well maintained in subzero conditions. Capacitive pressure sensors of the organohydrogels possessing a GF of 2.05 kPa−1, high sensing stability and reversibility, are demonstrated and explored in monitoring diverse human motions.

New Methods for the Functionalization of Polymer Matrices with Thiomolybdate Clusters Applied for Hydrogen Evolution Reaction Catalysis

The embedding of molecular reactive species such as catalysts into polymers opens up new avenues for advanced composite design for energy technologies and beyond. Herein, two new approaches for the connection of molecular molybdenum sulfide clusters and synthetic polymers are presented. The approach one is based on the utilization of a molecular molybdenum sulfide cluster as a potential chain transfer agent in a free radical polymerization process. The second one is a postpolymerization functionalization of a thiol end‐functionalized polymer with a thiomolybdate cluster. Detailed characterization using Raman spectroscopy reveals the successful functionalization in the latter approach, whereas in the other one, a noncovalent interaction is suggested. Furthermore, visible light‐driven hydrogen evolution demonstrates that the molecular molybdenum sulfide cluster retains its catalytic activity after the combination with polymers.

Panchromatic Copper Complexes for Visible Light Photopolymerization

In this work, eleven heteroleptic copper complexes were designed and studied as photoinitiators of polymerization in three-component photoinitiating systems in combination with an iodonium salt and an amine. Notably, ten of them exhibited panchromatic behavior and could be used for long wavelengths. Ferrocene-free copper complexes were capable of efficiently initiating both the radical and cationic polymerizations and exhibited similar performances to that of the benchmark G1 system. Formation of acrylate/epoxy IPNs was also successfully performed even upon irradiation at 455 nm or at 530 nm. Interestingly, all copper complexes containing the 1,1′-bis(diphenylphosphino)ferrocene ligand were not photoluminescent, evidencing that ferrocene could efficiently quench the photoluminescence properties of copper complexes. Besides, these ferrocene-based complexes were capable of efficiently initiating free radical polymerization processes. The ferrocene moiety introduced in the different copper complexes affected neither their panchromatic behaviors nor their abilities to initiate free radical polymerizations.

Enhanced mechanical, biomineralization, and cellular response of nanocomposite hydrogels by bioactive glass and halloysite nanotubes for bone tissue regeneration

In the present study, the synergistic effect of the bioactive glass (BG) and halloysite nanotubes (HNTs) (i.e. BG@HNT) was evaluated on physicochemical and bioactive properties of polyacrylamide/poly (vinyl alcohol) (PMPV) based nanocomposite hydrogels. Here, a double-network hydrogel composed of organic-inorganic components was successfully developed by using in-situ free-radical polymerization and freeze-thawing process. Structural analyses confirmed the successful formation of the nanocomposite hydrogels through physical and chemical interactions. Morphological analysis showed that all hydrogel scaffolds are containing highly porous 3D microstructure and pore-interconnectivity. The equilibrium swelling ratio of the hydrogels was decreased by the addition of BG or BG@HNT and thereby the lower porosity and pore-size reduced the penetration of media and slow down the degradation process. Enhanced biomineralization ability of PMPV/BG@HNT was observed via apatite-forming ability (Ca/P: 1.21 ± 0.14) after immersion in the simulated body fluid as well as significantly enhanced dynamic mechanical properties (compressive strength: 102.1 kPa at 45% of strain and stiffness: 3115.0 N/m at 15% of strain). Furthermore, an enhanced attachment and growth of hFOB1.19 osteoblast cells on PMPV/BG@HNT was achieved compared to PMPV or PMPV/BG hydrogels over 14 days. The PMPV/BG@HNT nanocomposite hydrogel could have a promising application in low-load bearing bone tissue regeneration.

Effect of silicate sodium and graphene nanoplatelets on morphology and rheology characteristics of new synthesized preformed particle gel (PPG) for water shut-off treatment

Water flooding is one of the most common enhanced oil recovery (EOR) methods, however its application in naturally fractured reservoirs (NFR), suffers from the flow of water in high permeable channels and fractures which leads to low areal and volumetric sweep efficiency. Preformed Particle Gels (PPG), as a subset of gel treatments, can play a vital role in plugging super-permeable zones either near wellbore or deep in the reservoir. Nevertheless the mechanical strength and thermal stability of the designed PPGs, especially under harsh environmental conditions, are subject to further research and development. In spite of recent studies, the effects of nano-materials on the rheological and morphological properties of the PPGs are not systematically investigated and understood. In this study novel PPGs were designed and synthesized (using free radical polymerization process) for application at harsh environments in terms of temperature, pH and salinity. To investigate the effectiveness of the designed PPG samples static swelling bulk tests as well as dynamic Hele-Shaw tests are performed. The examined parameters in static tests include various pH of the environment, the type and concentration of ions in the brine, temperature, dehydration durability and presence of carbon dioxide. In addition, to enlighten the mechanisms behind the performance of the new designed PPGs, comprehensive set of rheological tests (evaluation of both storage and elastic modules) as well as SEM and ESEM image analysis of dry and swollen particles are performed. Taking advantages of silicate sodium gelation capacity and functionalization of graphene nano-platelets (GNP), novel monolithic gel samples (SNGP) with unique qualities are synthesized. Although the addition of sodium silicate and GNP reduced the swelling capacity of the gels, they have significantly improved the rheological properties of the PPG samples. Rheological tests, confirmed that by adding only 0.1 wt% graphene nano-platelets and 0.5 wt% sodium silicate, the storage module of the swollen gel increased three times. Additionally the main advantage of the samples SNGP sample is its stability at harsh conditions such as high salinity, high as well as low pH, high temperature and its dehydration durability. SEM images of dry particles shows that presence of both silicate sodium and GNP has improved the harmonization of the networked structure, with making it thicker and denser. This has increased the porous interrelated structure which in turn is responsible for strong and improved mechanical properties of the SNGP gels. ESEM images of the swollen samples shows that the uniformly porous network structure of hydrogels is led to the maximum water holding capacity, which contributes to good stability of the 3D network structure of swollen PPGs under dehydration and thermal tests. Additionally, this improved microstructure can explain the compressive strengths increment with adding up nano-graphene and silicate content. The two PPG samples with the most suitable specification in the bulk tests were selected for further performance analysis in dynamic tests through Hele-Shaw cell setup. The experimental results in this transparent fracture model showed that increasing salinity causes the increase of the residual resistance factor (Frr). The results showed that the plugging efficiency and the damage factor are directly related to the PPGs size, water salinity and concentration of both GNP and silicate sodium. It is demonstrated that SNGP sample containing 50% size of 1190–595 μm and 50% size of 297–177 μm (larger size distribution) has a higher plugging capability compared to the samples containing each of these particles sizes alone. Additionally both bulk tests and Hele-Shaw cell tests approved that synthesized PPGs are also applicable for CO 2 injection. • New PPG is synthesized to be applicable in harsh environments such as low/high pH, high salinity and high temperature. • Sodium silicate and graphene nano-platelets improved temperature resistance and dehydration durability properties. • Static swelling bulk tests and dynamic Hele-Shaw cell tests are performed to evaluate the water shut-off performance. • Different rheological tests are performed to evaluate the mechanical and rheological properties of the designed hydrogels. • SEM and ESEM are used to shed light on the morphology of the samples and the reason behind improved properties.

Anionic hydrogel fabricated with metal nanoparticles: highly efficient and easily recyclable catalysts

ABSTRACT Herein, we synthesized poly(methacrylic acid) [p(MAAc] hydrogels by an effective and simple free radical polymerization process and then silver, cobalt, and their bimetallic nanoparticles (NPs) were synthesized by using p(MAAc) as a template. Upon loading of Ag (I) and Co (II) ions by p(MAAc) hydrogels from their corresponding aqueous salt solutions, these metal ions loaded hydrogels were then treated with sodium borohydride, a reducing agent to obtain corresponding metal nanoparticles (NPs) within the hydrogel network. Hydrogels and metal nanoparticle containing composite hydrogels were analyzed in detail by Transmission Electron Microscopy, X-ray Diffraction, Fourier Transform Infra-red spectroscopy, UV-Vis Spectrophotometry and Thermal Gravimetric Analysis techniques. Synthesized p(MAAc)-M hydrogel composites were utilized as catalysts for degradation of some harmful organic residual dyes like Eosin Y (EY), methyl orange (MO) along with reduction studies of some nitro aromatic compounds including 2-nitrophenol (2-NP), 4-nitrophenol (4-NP), 4-nitroaniline (4-NA) to their respective amino phenolic compounds from contaminated water. Above all, we also report simultaneous degradation studies of a dye EY and a nitro compound, 4-NP catalyzed by p(MAAc)-Ag composite hydrogel. The parameters such as nature of metal, catalyst amounts, temperature, water samples from different resources, and reusability of prepared hydrogel-metal nanoparticle nanocomposite catalysts were also investigated.