Synthetic Gel Research Articles

Polymerization-Induced Self-Assembly Providing PEG-Gels with Dynamic Micelle-Crosslinked Hierarchical Structures and Overall Improvement of Their Comprehensive Performances.

Polymer gels are fascinating soft materials and have become excellent candidates for wearable electronics, biomedicine, sensors, etc. Synthetic gels usually suffer from poor mechanical properties, and integrating good mechanical properties, adhesiveness, stability, and self-healing performances in one gel is more difficult. Herein, polymerization-induced self-assembly (PISA) providing PEG-gels with an overall improvement in their comprehensive performances is reported. PISA synthesis is carried out in PEG (solvent) to efficiently produce various nanoparticles, which are used as the nanofillers in the subsequent synthesis of PEG-gels with dynamic micelle-crosslinked hierarchical structures. Compared to hydrogels, PEG-gels show excellent long-term stability due to the nonvolatile feature of PEG solvent. The hierarchical PEG-gels (with nanofillers) exhibit better mechanical and adhesive properties than the homogeneous-gels (without nanofillers). The energy dissipation mechanism of the PEG-gels is analyzed via stress relaxation and cyclic mechanical tests. High-density hydrogen bonds between the micelles and PAA matrix can be broken and reformed, endowing better self-healing properties of the dynamic micelle-crosslinked PEG gels. This work provides a simple strategy for producing hierarchical structural gels with enhanced properties, which offers fundamentals and inspirations for the designing of various advanced functional materials.

Clinical Anatomy of Vessels of Popliteal Region

INTRODUCTION: A modern standard for noninvasive diagnostics of the vascular system is duplex scanning. The knowledge of variability of vascular anatomy is essential for ultrasound doctors. AIM: To clarify variants of the clinical anatomy of vessels of the popliteal region using duplex scanning and anatomical preparation. MATERIALS AND METHODS: The work used data of duplex scanning of the arteries and veins of the lower extremities of patients without pathology of the vascular system of the lower extremities, who underwent examination of the vascular system: 200 patients aged from 18 to 92 years. As control, the data of anatomical preparation of 50 amputated lower extremities were taken, with preliminary filling the venous system with a blue synthetic gel. RESULTS: In the course of anatomical preparation, two trunks of the popliteal vein were identified in the distal popliteal region in 86.0% of observations. A typical drain of the small saphenous vein with formation of the saphenopopliteal junction was encountered in 60.0% of cases. In duplex scanning, a high bifurcation of the popliteal artery was detected in 1.9% of observations. The two trunks of the popliteal vein in the distal part of the popliteal region were encountered in 82.4% of cases, and the medial trunk was almost always larger than the lateral one. The small saphenous vein drained into the popliteal vein in 63.0% of cases. In 7.2% of observations, it drained into one of the intramuscular veins. In 0.95% of observations, a perforator vein was identified in the popliteal region. The sural veins were identified in all the patients — two on the medial and lateral surface positioned at the sides of the two trunks of the sural arteries, forming a single trunk before confluence with the popliteal vein. CONCLUSIONS: TThe study revealed the following anatomic variants of vessels of the popliteal region: two trunks of the popliteal vein below the knee joint cleft in 85.7% to 86.0% of observations; a high bifurcation of the popliteal artery in 1.9%; saphenopopliteal junction in 60.0% to 63.0%; perforator veins of the popliteal region in 0.95% of observations; upon that, the small saphenous vein does not form the saphenopopliteal junction.

Aloe vera Cuticle: A Promising Organic Water-Retaining Agent for Agricultural Use

Water is an important resource for both human and environmental survival. However, due to current human practices, we are facing a serious crisis in accessing water. Thus, solutions must be explored to optimize the use of this resource. In the search for an organic water-retaining agent for agricultural use, the techno-functional properties of Aloe vera (Aloe barbadensis Miller) cuticle, an agro-industrial residue generated after gel extraction, were evaluated. The residue was dried and ground. The effects of particle size (180 µm and 250 µm), temperature (10 °C, 20 °C, 30 °C, and 40 °C), and pH (4.5, 6.0, and 7.0) on the solubility and water-holding capacity (WHC) of the obtained product (i.e., hydrogel) were then evaluated. The treatment with the highest WHC was selected and compared with the WHC of a commercial synthetic polyacrylamide gel widely used in agriculture. The effects of KNO3 and Ca(NO3)2 at different concentrations (10 g L−1, 20 g L−1, 30 g L−1, and 40 g L−1) on the WHC of the gels were assessed. Particle size, temperature, and pH interactions had statistically significant effects on solubility, while the WHC was affected by particle size × temperature and pH × temperature interactions. The highest product solubility (75%) was obtained at the smallest particle size (i.e., 180 µm), pH 4.5, and 20 °C. Meanwhile, the highest WHC (18 g g−1) was obtained at the largest particle size (i.e., 250 µm), pH 6.0, and 20 °C. This optimized gel kept its WHC across both salts and their concentrations. In contrast, the commercial gel significantly decreased its WHC with salt concentration. The product elaborated with A. vera cuticle could have bioeconomic potential as a water-retention agent for agricultural use, with the advantage that it is not affected by the addition of salts used for plant fertilization.

Removal Forces of a Helical Microwire Structure Electrode.

(1) Background: Medical devices, especially neuromodulation devices, are often explanted for a variety of reasons. The removal process imparts significant forces on these devices, which may result in device fracture and tissue trauma. We hypothesized that a device's form factor interfacing with tissue is a major driver of the force required to remove a device, and we isolated helical and linear electrode structures as a means to study atraumatic removal. (2) Methods: Ductile linear and helical microwire structure electrodes were fabricated from either Gold (Au) or Platinum-Iridium (Pt-Ir, 90-10). Removal forces were captured from synthetic gel models and following chronic implantation in rodent and porcine models. Devices were fully implanted in the animal models, requiring a small incision (<10 mm) and removal via tissue forceps. (3) Results: Helical devices were shown to result in significantly lower maximal removal forces in both synthetic gel and rodent studies compared to their linear counterparts. Chronically (1 yr.), the maximal removal force of helical devices remained under 7.30 N, for which the Platinum-Iridium device's tensile failure force was 32.90 ± 2.09 N, resulting in a safety factor of 4.50. (4) Conclusions: An open-core helical structure that can freely elongate was shown to result in reduced removal forces both acutely and chronically.

Synthetic oil gels with organoclays in the formulation of magnetorheological fluids

Magnetorheological fluids (MRF) are smart composite materials that, under an external magnetic field, show a reversible solid-liquid transition in less than 10 ms. This study aimed to evaluate which organoclays would jellify a synthetic oil for the formulation of MRF. Three dispersant additives for carbonyl iron powder were evaluated. Fifteen different gelling additives from four clay families, bentonites, hectorites, montmorillonites, and mixed mineral thixotropes (MMT), were dispersed in oil only, keeping the same concentration, without iron particles. The gels were then tested through amplitude and frequency sweeps in oscillatory rheometry to evaluate their viscoelastic behavior. The thixotropy of the gels was measured through the “three-interval” test in a rheometer. After selecting the best gelling additive to prepare the MRF, three dispersing additives had their rheology evaluated to determine the best magnetorheological effect and redispersibility after 1 year of sample preparation. In the linear viscoelastic region, all MMT clays resulted in a weak viscoelastic gel (G′∼100 to 300 Pa and G″∼30 to 50 Pa). Some of the bentonite clays jellified, and others did not. The best organoclays were montmorillonites and hectorites, which formed consistent viscoelastic gels (G′∼1 to 5 kPa and G″∼70 to 250 Pa). The best organoclay presented a yield stress σ0 = (42 ± 3) Pa, a storage modulus G′ = (2690 ± 201) Pa, and a cohesive energy density (CED) = 98 mJ/m3, and it was selected to explore the rheology of MRF with three dispersant additives: octan-1-ol, octan-1-amine, and L-α-Phosphatidylcholine. All the MRFs were prepared using carbonyl iron powder HS (BASF SE) in oil gels and with the same organoclay. All three dispersant additives showed a thixotropic recovery above 100% in the three-interval test. Regarding the redispersibility after 1 year, the MRF formulations with octan-1-amine and lecithin were reproved, as they reached normal force peaks of 19 and 24 N, while the work was 28 and 415 mJ, respectively. The best MRF was formulated with octan-1-ol, and resulted in a normal force of 0.33 N and 3.4 mJ at 35 mm of vane penetration. Therefore, we conclude that the MRF with octan-1-ol and montmorillonite #6 showed a better balance between thixotropy, MR effect, and, above all, good redispersibility.

Dielectric properties of PANI‐PEG nanocomposites filled with silica media for antistatic applications

AbstractThe dielectric investigations of porous synthetic silica gel modified with polyaniline (PANI) and polyethylene glycol (PEG) polyblend at various concentrations are demonstrated in this paper. By using the chemical oxidative process to embed polyaniline (PANI) and polyethylene glycol (PEG) into a silica matrix, conducting gel nanocomposites were synthesized. For various dopant concentrations, the dielectric permittivity (ε′), D.C. conductivity (σdc), loss tangent (tanδ) and dielectric loss (ε″) were investigated. The samples were characterized using differential thermal analysis/thermogravimetric analysis, Fourier transform infrared spectroscopy and high‐resolution transmission electron microscopy. Depending on the co‐blend content, PANI‐PEG modified silica structures produce nanoparticles ranging in size from 9.9 to 48.1 nm. The variation of DC conductivity (σdc) with PANI/PEG content shows Maxwell‐Wagner Sillars (MWS) effect confirming the role of the conjugation and the structural order.

Intensification of oil production through the use of hydraulic fracturing fluid based on polyacrylamide

The article considers the technology of Hydraulic Fracturing (HF) based on polyacrylamide (Co-PAM), identifies parameters for evaluating the quality of the fluid both on a guar and polyacrylamide base. Fluid viscosity is a main criteria of success of HF operations. Thus, fluid thermal stability, determine the pumping time. The composition of the Co-PAM-based HF fluid differs from the guar-based one, consisting of two main chemical reagents - a gelling agent and a crosslinker(x-linker), in that only a synthetic gelling agent is used. Recommended concentration starts from 4 l/m3. At this concentration the synthetic gel starts to exhibit properties of a sand-carrying fluid, suitable for standard pump rate (4.0-5.0 m3/min) HF. A significant advantage is compliance with the requirements for HF fluids which not only improves the filtration properties of the formation but also considers the economic feasibility of using such a chemical reagent. Co-PAM gel using provides reduction of logistics costs, water heating. Also it allows to exclude hydration unit, reduced crew, decreased wear on pumping units, including reduced consumption of lubricants during the HF operation.

Analysis of the adhesive secreting cells of Arion subfuscus: insights into the role of microgels in a tough, fast-setting hydrogel glue.

The slug Arion subfuscus produces a tough, highly adhesive defensive secretion. This secretion is a flexible hydrogel that is toughened by a double network mechanism. While synthetic double network gels typically require extensive time to prepare, this slug creates a tough gel in seconds. To gain insight into how the glue forms a double-network hydrogel so rapidly, the secretory apparatus of this slug was analyzed. The goal was to determine how the major components of the glue were distributed and mixed. Most of the glue comes from two types of large unicellular glands; one secretes polyanionic polysaccharides in small, membrane-bound packets, the other secretes proteins that appear to form a cross-linked network. The latter gland shows distinct regions where cross-linking appears to be occurring. These regions are darker, more homogeneous and appear more solid than the rest of the secretory material. The enzyme catalase is highly abundant in these regions, as are basic proteins. These results suggest that a rapid oxidation event occurs in this protein-containing gland, triggering cross-linking before the glue is released. The cross-linked microgels would then join together after secretion to form a granular hydrogel. The polysaccharide-filled packets would be mixed and interspersed among these microgels and may contribute to joining them together. This is an unexpected and highly effective way to form a tough gel rapidly.

Insight into the cross-linking of synthetic polypeptide gels prepared by ring-opening polymerization using l-cystine N-carboxyanhydride

Synthetic polypeptides have promising potential for various biomedical applications that often require a cross-linked network for stability against solvents or mechanical stress. Due to the natural occurrence and availability of the l-cystine α-amino acid, l-cystine N-carboxyanhydride (NCA) is commonly used as a cross-linker in the ring-opening (co)polymerization of α-amino acid NCAs to prepare covalently cross-linked synthetic polypeptides. In this work, we show that the l-cystine NCA tends to undergo undesired decomposition side reactions, i.e., β-elimination and formation of 2,5-diketopiperazine, which reduce the amount of the cross-linker available and make it difficult to control the final properties of the materials prepared from it. By using the analogous l-homocystine NCA instead, the decomposition side reactions can be completely avoided. We demonstrate the cross-linking performance of l-cystine NCA compared to l-homocystine NCA by studying the corresponding gels prepared by copolymerization with γ-benzyl-l-glutamate NCA.

Acid-modulated synthesis of ultra-thin Ti-MWW zeolite nanosheets for the efficient epoxidation of cycloalkenes with tert-butyl hydroperoxide

The Ti-MWW zeolites with a layered morphology, synthesized by a conventional method, usually show low catalytic activities in the epoxidation of bulky alkenes due to the serious steric constraint imposed by the zeolite micropores and the adverse effects from some extra-framework octahedral Ti species. In the present work, the Ti-MWW zeolite was prepared by the reaction of an ultra-thin layered borosilicate MWW-type zeolite (D-ERB-1) with tetrabutyl orthotitanate (TBOT) in a HNO3 aqueous solution, wherein D-ERB-1 was hydrothermally synthesized by introducing an organosilane into the synthetic gel. In combination with the results from extensive characterizations for the synthesized zeolites, it is found that the currently synthesized Ti-MWW zeolite without extra-framework octahedral Ti species has thinner nanosheets that are very helpful to the epoxidation of cycloalkenes with tert-butyl hydroperoxide (TBHP), and is more active than the conventional Ti-MWW and other titanosilicate zeolites. Moreover, the developed catalyst is recyclable after the regeneration of the deactivated zeolite by washing with acetonitrile (MeCN). Therefore, the present work provides some guidance in the development of an efficient titanosilicate catalyst for the epoxidation of bulky alkenes.

High-strength and high-toughness ECM films with the potential for peripheral nerve repair

Extracellular matrix (ECM) scaffolds are widely applied in the field of regeneration as the result of their irreplaceable biological advantages, and the preparation of ECM scaffolds into ECM hydrogels expands the applications to some extent. However, weak mechanical properties of current ECM materials limit the complete exploitation of ECM’s biological advantages. To enable ECM materials to be utilized in applications requiring high strength, herein, we created a kind of new ECM material, ECM film, and evaluated its mechanical properties. ECM films exhibited outstanding toughness with no cracks after arbitrarily folding and crumpling, and dramatically high strength levels of 86 ± 17.25 MPa, the maximum of which was 115 MPa. Such spectacular high-strength and high-toughness films, containing only pure ECM without any crosslinking agents and other materials, far exceed current pure natural polymer gel films and even many composite gel films and synthetic polymer gel films. In addition, both PC12 cells and Schwann cells cultured on the surface of ECM films, especially Schwann cells, showed good proliferation, and the neurite outgrowth of the PC12 cells was promoted, indicating the application potential of ECM film in peripheral nerve repair.

Evolutionary Reinforcement of Polymer Networks: A Stepwise-Enhanced Strategy for Ultrarobust Eutectogels.

Gel materials are appealing due to their diverse applications in biomedicine, soft electronics, sensors, and actuators. Nevertheless, the existing synthetic gels are often plagued by feeble network structures and inherent defects associated with solvents, which compromise their mechanical load-bearing capacity and cast persistent doubts about their reliability. Herein, combined with attractive deep eutectic solvent (DES), a stepwise-enhanced strategy is presented to fabricate ultrarobust eutectogels. It focuses on the continuous modulation and optimization of polymer networks through complementary annealing and solvent exchange processes, which drives a progressive increase in both quantity and mass of the interconnected polymer chains at microscopic scale, hence contributing to the evolutionary enhancement of network structure. The resultant eutectogel exhibits superb mechanical properties, including record-breaking strength (31.8MPa), toughness (76.0MJ m-3 ), and Young's modulus (25.6MPa), together with exceptional resistance ability to tear and crack propagation. Moreover, this eutectogel is able to be further programmed through photolithography to in situ create patterned eutectogel for imparting specific functionalities. Enhanced by its broad applicability to various DES combinations, this stepwise-enhanced strategy is poised to serve as a crucial template and methodology for the future development of robust gels.

An extended focused assessment with sonography in trauma ultrasound tissue-mimicking phantom for developing automated diagnostic technologies.

Introduction: Medical imaging-based triage is critical for ensuring medical treatment is timely and prioritized. However, without proper image collection and interpretation, triage decisions can be hard to make. While automation approaches can enhance these triage applications, tissue phantoms must be developed to train and mature these novel technologies. Here, we have developed a tissue phantom modeling the ultrasound views imaged during the enhanced focused assessment with sonography in trauma exam (eFAST). Methods: The tissue phantom utilized synthetic clear ballistic gel with carveouts in the abdomen and rib cage corresponding to the various eFAST scan points. Various approaches were taken to simulate proper physiology without injuries present or to mimic pneumothorax, hemothorax, or abdominal hemorrhage at multiple locations in the torso. Multiple ultrasound imaging systems were used to acquire ultrasound scans with or without injury present and were used to train deep learning image classification predictive models. Results: Performance of the artificial intelligent (AI) models trained in this study achieved over 97% accuracy for each eFAST scan site. We used a previously trained AI model for pneumothorax which achieved 74% accuracy in blind predictions for images collected with the novel eFAST tissue phantom. Grad-CAM heat map overlays for the predictions identified that the AI models were tracking the area of interest for each scan point in the tissue phantom. Discussion: Overall, the eFAST tissue phantom ultrasound scans resembled human images and were successful in training AI models. Tissue phantoms are critical first steps in troubleshooting and developing medical imaging automation technologies for this application that can accelerate the widespread use of ultrasound imaging for emergency triage.

Development of a semi-anthropomorphic photoacoustic calcaneus phantom based on nano computed tomography and stereolithography 3D printing.

Osteoporosis is a major public health threat with significant physical, psychosocial, and financial consequences. The calcaneus bone has been used as a measurement site for risk prediction of osteoporosis by noninvasive quantitative ultrasound (QUS). By adding optical contrast to QUS, our previous studies indicate that a combination of photoacoustic (PA) and QUS, that is, PAQUS, provides a novel opportunity to assess the health of human calcaneus. Calibration of the PAQUS system is crucial to realize quantitative and repeatable measurements of the calcaneus. Therefore, a phantom which simulates the optical, ultrasound, and architectural properties of the human calcaneus, for PAQUS system calibration, is required. Additionally, a controllable phantom offers researchers a versatile framework for developing versatile structures, allowing more controlled assessment of how varying bone structures cause defined alterations in PA and QUS signals. In this work, we present the first semi-anthropomorphic calcaneus phantom for PAQUS. The phantom was developed based on nano computed-tomography (nano-CT) and stereolithography 3D printing, aiming to maximize accuracy in the approximation of both trabecular and cortical bone microstructures. Compared with the original digital input calcaneus model from a human cadaveric donor, the printed model achieved accuracies of 71.15% in total structure and 87.21% in bone volume fraction. Inorganic materials including synthetic blood, mineral oil, intralipid, and agar gel were used to model the substitutes of bone marrow and soft tissue, filling and covering the calcaneus phantom. The ultrasound and optical properties of this phantom were measured, and the results were consistent with those measured by a commercialized device and from previous in vivo studies. In addition, a short-term stability test was conducted for this phantom, demonstrating that the optical and ultrasound properties of the phantom were stable without significant variation over 1 month. This semi-anthropomorphic calcaneus phantom shows structural, ultrasound, and optical properties similar to those from a human calcaneus in vivo and, thereby, can serve as an effective source for equipment calibration and the comprehensive study of human patients.

Enhancing the stability of natural anthocyanins against environmental stressors through encapsulation with synthetic peptide-based gels

The instability of anthocyanin to environmental stressors severely limits its applications as a natural bioactive pigment. To overcome these limitations, this proof-of-concept study utilizes the high biocompatibility of peptide molecules and the unique gel microstructure to develop innovative peptide-based gels. Characterization of the gels was conducted through AFM, SEM, rheological analysis, and CD spectrum. These analyses confirmed the fibrous mesh structure and impressive mechanical strength of the peptide-based gels. The cytotoxicity evaluation using MTT and hemolysis analysis showed high biocompatibility. Encapsulation efficiency analysis and fluorescence microscopy images demonstrated successful and efficient encapsulation of anthocyanins in all four peptide-based gels, with uniform distribution. Moreover, systematic investigations were conducted to assess the impact of peptide-based gels on the stability of natural anthocyanins under environmental stressors such as temperature, pH variations, and exposure to metal ions. Notably, the results revealed a significant enhancement in stability, including improved long-term storage and antioxidant activity. In conclusion, this study successfully developed four novel peptide-based gels that effectively protect natural anthocyanins from environmental stressors, highlighting their potential in various fields such as food and biology.

A Free, Open-Source Toolkit to Produce 3D Bolus in the Clinic

Tissue-equivalent, tissue-approximating and tissue-replacing bolus materials have been in use for decades in radiotherapy. Most frequently these materials are applied to a patient's skin to bring the highest dose region towards the surface of the skin-which is the location of the target. These materials can be applied at the time of simulation and included in a planning CT scan, or can be added during the planning process and first physically applied at the time of treatment. One of the most widely adopted materials for bolus has been sheets of a commercially available proprietary synthetic gel, which is uniform in thickness, and has some ability to match the curvature of the patient's body. Recently investigators have worked to create boluses using 3D printing technology, including several commercially available offerings. We hypothesized that we could create a bespoke, 3D bolus solution, using a series of open-source and free software products. For an anthropomorphic phantom, a radiation treatment plan representative of skin cancer treatment was designed, this included a superficial target. The DICOM CT and structure set were imported into 3D Slicer, which is a free, open-source software for visualization, processing, segmentation, and registration. Using 3D Slicer, the bolus structure was saved as an STL file. Meshmixer, a free software for working with triangle meshes, was used to complete a mold design, and the mold parts were then printed using a rigid filament on a 3D printer. The mold parts were glued together, and small spring clamps were used secure the walls to the shells to ensure mold integrity. The mold was then filled with a thinned and degassed silicone. After appropriate curing, demolding was completed by removing the clamps and separating the walls. After QA, the bolus was applied to the anthropomorphic phantom and CTs were taken to compare a commercial sheet bolus with the in-house 3D printed product. The bolus made via the in-house 3D printing process fit even complicated patient geometries well, and had both an obvious visual/goodness of fit advantage over the commercial sheet bolus and a nuanced dosimetric improvement as the air gaps present in the commercial sheet bolus were not desirable nor reproducible. The overall in-house workflow was efficient, and clinically reasonable (an estimated time of 72 hours was presented to the physician team, but in testing less than 24 hours was needed from export to delivery of the finished product). In this work we explored whether motivated groups and departments could produce dosimetrically accurate and clinically reasonable custom boluses for patients undergoing radiotherapy to a superficial area of the body, using a test case on an anthropomorphic phantom. We found that this was absolutely achievable and could be implemented with no funds spent on software or licenses. Provided that a 3D printer, filament and silicone are available, any thoughtful practice can join the bespoke-bolus-club.

Amide-assisted synthesis of TS-1 zeolites with active Ti(OH2)2(OH)2(OSi)2 sites toward efficient oxidative desulfurization

Aiming to promote the activity of TS-1 zeolite in catalytic oxidative desulfurization (ODS), a general amide-assisted strategy was proposed to synthesize hierarchical TS-1 zeolite with rich and homogeneously distributed Ti(OH2)2(OH)2(OSi)2 species. Strong interactions between acrylamide (AM) and Si/Ti as well as self-polymerization of AM in synthetic gels change the zeolite formation process, thus to effectively construct Ti(OH2)2(OH)2(OSi)2, promote Ti evenly distribution and form micro-mesopore structure. The activity of Ti(OH2)2(OH)2(OSi)2 was evaluated by ODS of refractory sulfur-containing compounds. The advantages of Ti(OH2)2(OH)2(OSi)2 over TiO4 in substrate adsorption and reactive intermediate formation for ODS were further proved by theoretical calculations. By adjusting AM amount to optimize the Ti(OH2)2(OH)2(OSi)2 content and distribution, the obtained catalyst achieves 134.8 h-1 of turnover frequency and 100 % DBT removal at ten minutes, and maintains > 92 % removal after seven cycles at 333 K. This facile active-site construction strategy is promising to be extended to other heteroatom-containing zeolite catalysts.

Advancements in numerical modelling of synthetic gel for ballistic impact assessment

A synthetic gel based on SEBS (styrene-ethylene-butylene-styrene), commonly used as a human soft tissue simulant, was characterised over a wide range of strain rates. Material parameters were derived from quasi-static and dynamic tests using DMA. These parameters were then integrated into a visco-hyperelastic material law based on an Ogden model. Ballistic impact simulations showed good agreement with experimental analysis.

Tailoring the pore structure、morphology and acidity of MFI zeolites by the regulation of Si/Al ratio in the synthetic gel

In this work, we report a facile and low-cost approach for controllable preparation of hierarchical mesoporous MFI zeolites via simply manipulating the Si/Al ratio in the initial synthetic precursor. The results demonstrate that Si/Al ratio significantly influences not only the acidity but also the pore structure as well as morphology of MFI zeolites. With the increase of Si/Al ratio, the mesoporous structures are weakened due to the increasingly severe crystal fusion leading to the formation of bulk zeolite crystal and the acid amounts decrease as well. The optimal sample Z-55 with spherical morphology is composed of numerous superfine nanocrystals. These primary results are quite beneficial to guiding reasonable design of the zeolites with other topologies. In LDPE cracking, the sample Z-55 with tri-modal mesopores distributions performs enhanced catalytic activity compared with convention MFI zeolite and the T50 is reduced to 391 °C, mainly ascribed to the luxuriant mesoporous structures.

Preparation of high-performance zeolite membrane on a macroporous support by novel intermittent hydrothermal synthesis

Constructing high-quality zeolite membrane by regulating solely the kinetics of zeolite nucleation and growth is desired because of its simplicity and potential industrial viability. Herein, a high-performance mordenite membrane was prepared without using organic template successfully on a macroporous tubular α-alumina support using a novel and simple intermittent hydrothermal synthesis (IHS) method. We aimed at regulating membrane synthesis kinetics by adjusting the concentration of the synthetic gel by introducing an unheated period of the oven in the middle stage of the synthesis process. In the proposed IHS method, the power supply of the oven can be switched off and on with the aid of a smart socket without manual operation, ensuring its feasibility and convenience. A thin and dense membrane layer was formed via the appropriate adjustment of presynthesis time, unheated time, and resynthesis time. The effects of each duration on the morphologies, microstructures, and pervaporation performances of the prepared mordenite membranes were investigated. Under optimized conditions, the as-synthesized mordenite membrane showed high pervaporation performance with a permeation flux and separation factor of 5.57 kg m−2 h−1 and >10000, respectively, in the dehydration of 90 wt% isopropanol/water mixture at 75 °C. This work provides a novel, simple, and feasible method for the preparation of high-performance zeolite membrane.