Search Results (134)

Deep coalbed methane (CBM) reservoirs are characterized by high hydrocarbon content and are considered an important strategic resource. Due to their inherently low permeability and porosity, horizontal well drilling is commonly employed to enhance production, with the length of the horizontal section playing a critical role in determining CBM output. However, during extended horizontal drilling, wellbore instability frequently occurs as a result of drilling fluid invasion into the coal formation, posing significant safety challenges. This instability is primarily caused by the physical intrusion of drilling fluids and their interactions with the coal seam, which alter the mechanical integrity of the formation. To address these challenges, interpenetrating and semi-interpenetrating network (IPN/s-IPN) hydrogels have gained attention due to their superior physicochemical properties. This material offers enhanced sealing and support performance across fracture widths ranging from micrometers to millimeters, making it especially suited for plugging applications in deep CBM reservoirs. A self-degradable interpenetrating double-network hydrogel particle plugging agent (SSG) was developed in this study, using polyacrylamide (PAM) as the primary network and an ionic polymer as the secondary network. The SSG demonstrated excellent thermal stability, remaining intact for at least 40 h in simulated formation water at 120 °C with a degradation rate as high as 90.8%, thereby minimizing potential damage to the reservoir. After thermal aging at 120 °C, the SSG maintained strong plugging performance and favorable viscoelastic properties. A drilling fluid containing 2% SSG achieved an invasion depth of only 2.85 cm in an 80–100 mesh sand bed. The linear viscoelastic region (LVR) ranged from 0.1% to 0.98%, and the elastic modulus reached 2100 Pa, indicating robust mechanical support and deformation resistance. Full article

A soluble photosensitive polyamide ester precursor (BAFPAE) was synthesized through copolymerization of 2,2-bis [4-(4-aminophenoxy)phenyl]hexafluoropropane (HFBAPP) with 4,4′-(4,4′-isopropylidenediphenoxy)bis(phthalic anhydride) (BPADA). Hydroxyethyl methacrylate (HEMA) was incorporated as a photosensitive functional group, and a transparent photosensitive polyimide film was obtained by thermal curing of the precursor film. The effects of reaction temperature and varying HEMA equivalents on the mechanical properties of the film were systematically investigated. The results indicated that the formation of polyacrylate-polyimide interpenetrating polymer networks (IPNs) was pivotal in preserving the mechanical integrity of the material. The optimized BAF-x-y exhibited a toughness of 12.69 MJ m³, a Young’s modulus of 2.86 GPa, an elongation at break of 21.16%, and a tensile strength of 92.68 MPa. Full article

Transparent high-performance polymers are essential to avoid damage in automotive headlights when exposed to environmental conditions. An approach involving the synthesis of reinforced interpenetrating polymer networks (IPNs) based on poly(methyl methacrylate) (PMMA)/poly(urethane) (PU) with crystalline cellulose (C) is here proposed. The valorization of single-use cups used for cold beverage applications into reinforcement nanoparticle agents is studied through structural and morphological analysis, revealing intermediate crystallinity (52.51%) with a mixture of Iα (52.9%) and Iβ (46.3%) polymorphs in which the initial fiber had no chemical modification after the involved pretreatments. The effect of dispersing 0.1 wt% of C (d = 29 nm and L= 85–200 nm) into 50/50 and 80/20 PMMA/PU ratios is studied as a reinforcement agent under aging and environmental conditions (ASTM D1435-20) for 672 h. PMMA₈₀/PU₂₀ (σ =4 MPa, ε = 54%, E = 7 MPa) led to lower mechanical properties than PMMA₅₀/PU₅₀ (stress σ =14 MPa, strain ε = 94%, E = 83 MPa). PMMA₅₀/PU₅₀/C is reinforced in σ and ε with C addition (σ = 19 MPa, ε = 41%, E = 585 MPa) while PMMA₈₀/PU₂₀/C reduces both (σ = 3 MPa, ε = 51%, E = 5 MPa). This study indicates that aging increases stress while maintaining strain in the first but decreases in the second. The optical properties indicate no severe damage after aging. Full article

With the aim of developing a wear-resistant ultraviolet (UV)-cured self-lubricating coating, this study investigated the impact of matrix components and lubricants on UV-cured interpenetrating polymer network-polyurethane acrylate (IPN-PUA) self-lubricating coatings. Four coatings with different monomer combinations were prepared, using isophorone diisocyanate (IPDI) or tolylene-2,4-diisocyanate (TDI) in combination with hydroxypropyl acrylate (HPA) or 2-hydroxyethyl acrylate (HEA). These coatings were denoted as IPDI-HPA, IPDI-HEA, TDI-HPA, and TDI-HEA, respectively. The surface morphologies, compositions, friction and wear properties, as well as the comprehensive performances were investigated. The results indicated that IPDI-HPA had the lowest surface roughness and that TDI-HEA had the smallest wear rate, while TDI-HPA showed the best overall performance (roughness of 1.485 μm, coefficient of friction (COF) of 0.746, and wear rate of 10.64 × 10⁻¹⁴ m³/N·m). With TDI-HPA as the matrix, graphite and polytetrafluoroethylene (PTFE) particles of different sizes were added as lubricants. The T-P-25F (TDI-HPA coating with 25 μm sized PTFE) coating had self-lubricating capabilities, as was manifested by a friction coefficient of 0.395, which was 47% lower than that of the pure TDI-HPA coating, and it simultaneously showed outstanding wear-resistance performance. The wear rate of the T-P-25F coating was 3.97 × 10⁻¹⁴ m³/N·m, 62.7% lower than that of the pure TDI-HPA coating. This research provides valuable guidance for optimizing the performance of such coatings and yields a self-lubricating coating with excellent wear resistance. Full article

Interpenetrating polymer networks (IPNs) are widely used as damping materials across various industries. However, they are susceptible to issues such as microcracking or fracture over long-term service periods. To address these challenges and improve the long-term performance of IPNs, this research focused on designing and synthesizing self-healing polyurethane (PU)/epoxy (EP) interpenetrating networks (PU/EP-IPNs) enhanced with dynamic disulfide bonds. The incorporation of these bonds significantly enhanced the damping and self-healing properties of the materials. The shape memory performance was evaluated, demonstrating high shape fixation rates of up to 95.0% and exceptional shape recovery rates of up to 99.7%. These results indicate the materials’ ability to revert to their original shape upon heating above the glass transition temperature (T_g). In addition, the effective damping temperature range of the material reached 61.4 °C, and the loss factor was 0.859. This indicates that the enhancement of damping performance is closely related to the increase in disulfide bond density. The formation of the IPN between PU and EP also contributed to improved mechanical and thermomechanical properties. These PU/EP-IPNs exhibit significant potential as innovative damping materials with self-healing capabilities. Full article

Hydrogels with tunable properties are of great interest for the development of advanced drug delivery systems. In this study, novel hydrogels with an interpenetrating polymer network (IPN) structure were obtained from the pH-responsive poly(methacrylic acid) (PMAA) and the neutral poly(N,N-dimethylacrylamide) (PDMAM). The newly synthesized IPN hydrogels were shown to be pH responsive with a 1.5 to 2.5 fold increase in their equilibrium swelling ratio at a pH above 5 which makes them appropriate for targeted intestine drug delivery. Moreover, their pH responsiveness was found to be strongly influenced by the IPN’s composition. The IPN hydrogels were loaded with PMH via swelling and the drug entrapment efficiency was found to depend on their swelling characteristic varying with the IPN’s composition from 20% to 60%. The drug release profiles were investigated under conditions resembling the oral route of drug application. The PMH release profiles appeared to follow Fickian diffusion at a stomach-like pH = 1.2 and sub-diffusion mechanism at an intestine-like pH = 6.8. The results from this study reveal that IPN hydrogels of PMAA and PDMAM are promising candidates for oral delivery of promethazine hydrochloridee demonstrating pH responsiveness and controllable swelling dependent on their composition. Further investigations are planned to fully reveal their potential as smart drug delivery systems. Full article

In this study, we developed a novel one-pot synthesis method to fabricate well-defined single-chain polymeric nanoparticles (SCNPs) integrated with interpenetrating polymer network (IPN) systems. The synthesis process involved an initial intramolecular crosslinking of poly(methyl methacrylate-co-glycidyl methacrylate) to form SCNP followed by intermolecular crosslinking to produce single-chain nanogel (SCNG) structures. In addition, the achieved single-chain polymeric nanoparticle was subsequently incorporated into an IPN structure through urethane bond formation and a Diels–Alder click reaction involving furfuryl methacrylate (FMA) and bismaleimide (BMI). The thermal properties, swelling behaviors, and morphologies of the resulting SCNP-IPN systems were investigated. This work presents a novel strategy that integrates the single-chain folding concept with IPN systems, providing a promising platform for the development of robust and functional polymeric materials with potential applications in advanced materials science. Full article

Understanding the adsorption features of polymer microgels with different chemical compositions and structures is crucial in studying the mechanisms of respective emulsion stabilization. Specifically, the use of stimuli-responsive particles can introduce new properties and broaden the application range of such complex systems. Recently, we demonstrated that emulsions stabilized by microgels composed of interpenetrating networks (IPNs) of poly-N-isopropylacrylamide (PNIPAM) and polyacrylic acid (PAA) exhibit higher colloidal stability upon heating compared to PNIPAM homopolymer and other relevant PNIPAM-based copolymer counterparts. In the present work, using pendant drop tensiometry, we studied the evolution of water–tetradecane interfacial tension during the adsorption of PNIPAM-PAA IPN particles, comparing them with single-network P-(NIPAM-co-AA) and PNIPAM microgels. The results showed that, despite having the same chemical composition, copolymer particles exhibit completely different adsorption behavior in comparison to other microgel architectures. The observed disparity can be attributed to the nonuniform distribution of charged acrylic acid groups within the P-(NIPAM-co-AA) network obtained through precipitation polymerization. Oppositely, the presence of IPN architecture provides a uniform distribution of different monomers inside respective microgels. Additionally, hydrogen bonding between PNIPAM and PAA subchains appears to reduce the electrostatic energy barrier, enhancing the ability of IPN particles to successfully cover the liquid interface. Overall, our findings confirm the efficiency of using PNIPAM-PAA IPN microgels for the preparation of oil-in-water emulsions and their stability, even when the temperature rises above the lower critical solution temperature of PNIPAM. Full article

Background/Objectives: This study is an attempt to reveal the potential of two types of interpenetrating polymer network (IPN) hydrogels based on poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(N,N-dimethylacrylamide) (PDMAM). These IPNs were evaluated for their potential for dermal delivery of the hydrophobic drug dexamethasone (DEX). Methods: The two types of IPNs were analyzed for their rheological behavior, swelling characteristics, and drug-loading capacity with DEX. Drug release profiles were studied in Franz diffusion cells in PBS media. Finally, the cytotoxicity of the PHEMA/PDMAM-based IPNs was studied against T-cell lymphoma cells (HUT-78) and a normal murine fibroblast cell line (CCL-1). Results: The rheological properties of these hydrogels show suitable mechanical properties for dermal application, with G′ values of ~10 kPa. From the rheological data, the mesh size of these hydrogels was found to be influenced by the type of the IPN and its composition, varying between 6.5 and 50 nm. The loading capacity of both IPN types and DEX entrapment efficiency were highly influenced by the IPN’s composition. The loading capacity of the IPNs can reach ~3.5%, with a DEX entrapment efficiency of ~35%. The PHEMA/PDMAM IPNs demonstrate an extended release profile with up to ~95% DEX released in 24 h, while PDMAM/PHEMA IPNs release no more than ~25% DEX in 24 h. The drug release profiles follow either non-Fickian diffusion (n~0.6) or case-II transport (n~0.9–1), depending on the IPN’s composition. The PHEMA/PDMAM-based materials were found to be non-cytotoxic against HUT-78 and CCL-1 cells. Conclusions: The study reveals that the IPNs of PHEMA and PDMAM appear to be suitable platforms for dermal delivery of dexamethasone as they have appropriate mechanical properties, providing tools to control drug loading and release, and they are biocompatible with human skin cells. Full article

The objective of this study is to evaluate the degradation of end-of-life BWRO membranes sourced from a factory in France by analyzing their water permeability, roughness, and chemical composition in order to diagnose the level of degradation incurred during their first life cycle in water softening. Following this, two new applications for the end-of-life BWRO membranes were investigated: (i) as ultrafiltration membranes (UF) for domestic effluent treatment and (ii) as cation exchange membranes (CEM) for use in fungal microbial fuel cells (FMFC). The UF membrane was renovated with an acetic acid treatment and, subsequently, used for domestic effluent filtration. The cation exchange membrane was developed in two steps: (i) chlorine treatment and (ii) the deposition of an Amer Sil layer, a functional coating formed by an interpenetrating polymer network (IPN) made of sulfonated polyether sulfone (S-PES) in a cross-linked matrix of acrylic acid and divinylbenzene. Full article

The need for new biomaterials to meet the needs of advanced healthcare therapies is constantly increasing. Polysaccharide-based matrices are considered extremely promising because of their biocompatibility and soft structure; however, their use is limited by their poor mechanical properties. In this light, a strategy for the reinforcement of dextran-based hydrogels and interpenetrated polymer networks (semi-IPNs and IPNs) is proposed, which will introduce multifunctional crosslinkers that can modify the network crosslinking density. Hydrogels were prepared via dextran methacrylation (DexMa), followed by UV photocrosslinking in the presence of diacrylate (NPGDA), triacrylate (TMPTA), and tetraacrylate (PETA) crosslinkers at different concentrations. The effect of these molecules was also tested on DexMa-gellan semi-IPN (DexMa/Ge) and, later, on IPN (DexMa/CaGe), obtained after solvent exchange with CaCl₂ in HEPES and the resulting Ge gelation. Mechanical properties were investigated via rheological and dynamic mechanical analyses to assess the rigidity, resistance, and strength of the systems. Our findings support the use of crosslinkers with different functionality to modulate the properties of polysaccharide-based scaffolds, making them suitable for various biomedical applications. While no significative difference is observed on enriched semi-IPN, a clear improvement is visible on DexMa and DexMa/CaGe systems when TMPTA and NPGDA crosslinker are introduced at higher concentrations, respectively. Full article

The potential antimicrobial and antibiofouling properties of previously synthesized PEG/NiPAAm interpenetrated polymer networks (IPNs) were investigated against three of the most common bacteria (E. coli, S. aureus, and S. epidermidis). The main goal was to evaluate the material’s biocompatibility and determine its potential use as an antifouling component in medical devices. This was intended to provide an alternative option that avoids drug usage as the primary treatment, thus contributing to the fight against antimicrobial resistance (AMR). Additionally, characterization and mechanical testing of the IPN were carried out to determine its resistance to manipulation processes in medical/surgical procedures. IPNs with different NiPAAm ratios exhibited excellent cytocompatibility with BALB/3T3 murine fibroblast cells, with cell viability values of between 90 and 98%. In addition, the results regarding the adsorption of albumin as a model protein showed a nearly constant adsorption percentage of almost zero. Furthermore, the bacterial inhibition tests yielded promising results, demonstrating effective pathogen growth inhibition after 48 h. These findings suggest the material’s suitability for use in biomedical applications. Full article

An alternative synthetic pathway was proposed for the optimization of synthesis to find a better correlation between the swelling and elasticity of hyaluronic acid-interpenetrated gels via temperature regulation. An experimental design methodology was presented for the synthesis of polyacrylamide/poly(acrylic acid sodium salt)/hyaluronic acid, PAAm/PSA/HyA, gels by modifying the one-pot procedure using free radical crosslinking copolymerization of AAm with the addition of anionic linear PSA chains in the presence of various amount of HyA, ranging between 0.05% and 0.20% (w/v). Semi-interpenetrated polymer network (IPN)-structured gels were designed with tunable elasticity, in which the extent of covalent crosslinking interactions is controlled by polymerization temperature ranging between −18 and 45 °C. Depending on the HyA content added in the synthesis and the polymerization temperature, the swelling ratio could be controlled. The addition of 0.05% (w/v) HyA increased the swelling of semi-IPNs, while the elastic modulus increased with increasing HyA content and decreased with the polymerization temperature. PAAm/PSA/HyA semi-IPNs showed the typical pH-sensitive swelling of anionic gels, and the swelling reached a maximum at a pH of 11.2. PAAm/PSA/HyA gels were tested for the removal of methyl violet from wastewater. Adsorption kinetics were shown to be well-fitted with the pseudo-second-order model using linear and nonlinear regression analysis. With the clear relationship between increased modulus and composition, this study enabled the fine-tuning of semi-IPN interactions by varying the polymerization temperature. Full article

This study investigates the crosslinking dynamics and swelling properties of pH-responsive poly(ethylene glycol) (PEG)/poly(acrylic acid) (PAA) interpenetrating polymer network (IPN) hydrogels. These hydrogels feature denser crosslinked networks compared to PEG single network (SN) hydrogels. Fabrication involved a two-step UV curing process: First, forming PEG-SN hydrogels using poly(ethylene glycol) diacrylate (PEGDA) through UV-induced free radical polymerization and crosslinking reactions, then immersing them in PAA solutions with two different molar ratios of acrylic acid (AA) monomer and poly(ethylene glycol) dimethacrylate (PEGDMA) crosslinker. A subsequent UV curing step created PAA networks within the pre-fabricated PEG hydrogels. The incorporation of AA with ionizable functional groups imparted pH sensitivity to the hydrogels, allowing the swelling ratio to respond to environmental pH changes. Rheological analysis showed that PEG/PAA IPN hydrogels had a higher storage modulus (G′) than PEG-SN hydrogels, with PEG/PAA-IPN5 exhibiting the highest modulus. Thermal analysis via thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) indicated increased thermal stability for PEG/PAA-IPN5 compared to PEG/PAA-IPN1, due to higher crosslinking density from increased PEGDMA content. Consistent with the storage modulus trend, PEG/PAA-IPN hydrogels demonstrated superior mechanical properties compared to PEG-SN hydrogels. The tighter network structure led to reduced water uptake and a higher gel modulus in swollen IPN hydrogels, attributed to the increased density of active network strands. Below the pK_a (4.3) of acrylic acid, hydrogen bonds between PEG and PAA chains caused the IPN hydrogels to contract. Above the pKa, ionization of PAA chains induced electrostatic repulsion and osmotic forces, increasing water absorption. Adjusting the crosslinking density of the PAA network enabled fine-tuning of the IPN hydrogels’ properties, allowing comprehensive comparison of single network and IPN characteristics. Full article

Significant developments have been achieved with the invention of hydrogels. They are effective in many fields such as wastewater treatment, food, agriculture, pharmaceutical applications, and drug delivery. Although hydrogels have been used successfully in these areas, there is a need to make them better for future applications. Interpenetrating polymer networks (IPNs) can be created to make hydrogels more adjustable and suitable for a specific purpose. IPN formation is an innovative approach for polymeric systems. It brings two or more polymer networks together with entanglements. The properties of IPNs are controlled by its chemistry, crosslinking density, and morphology. Therefore, it is necessary to understand characterization methods in order to detect the formation of IPN structure and to develop the properties of hydrogels. In recent studies, IPN structure in hydrogels has been determined via chemical, physical, and mechanical methods such as Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), X-ray diffraction (XRD), and rheology methods. In this paper, these characterization methods will be explained, recent studies will be scrutinized, and the effectiveness of these methods to confirm IPN formation will be evaluated. Full article