An alternative filament fabrication method as the basis for 3D-printing personalized implants from elastic ethylene vinyl acetate copolymer.

In this work, a novel tool for small-scale filament production is presented. Unlike traditional methods such as hot melt extrusion (HME), the device (i) allows filament manufacturing from small material amounts as low as three grams, (ii) ensures high diameter stability almost independent of the viscoelastic behavior of the polymer melt, and (iii) enables processing of materials with rheological profiles specifically tailored toward fused filament fabrication (FFF). Hence, novel materials, previously difficult to process due to HME limitations, become easily accessible for FFF for the first time. Here, we showcase the production of highly flexible drug-free, and drug-loaded filaments based on ethylene-vinyl acetate polymers with a vinyl acetate content of 28 w% (EVA28) and unprecedented high melt flow rates of up to 400 g/10 min. Owing to their low viscosity, FFF with low print nozzle sizes of 250 µm was achieved for the first time for EVA28. These small nozzle diameters facilitate 3D-printing of high-resolution structures in small-dimensional dosage forms such as subcutaneous implantable drug delivery systems, which can later be used for personalization. Consequently, the material portfolio for FFF is tremendously broadened, allowing material and formulation optimization toward FFF, independent of a preliminary extrusion process.

Peptide programming of supramolecular vinylidene fluoride ferroelectric phases.

Ferroelectric structures have spontaneous macroscopic polarization that can be inverted using external electric fields and have potential applications including information storage, energy transduction, ultralow-power nanoelectronics1,2 and biomedical devices3. These functions would benefit from nanoscale control of ferroelectric structure, the ability to switch polarization with lower applied fields (low coercive field) and biocompatibility. Soft ferroelectrics based on poly(vinylidene fluoride) (PVDF)4-6 have a thermodynamically unstable ferroelectric phase in the homopolymer, complex semi-crystalline structures, and high coercive fields. Here we report on ferroelectric materials formed by water-soluble molecules containing only six VDF repeating units covalently conjugated to a tetrapeptide, with the propensity to assemble into the ß-sheet structures that are ubiquitous in proteins. This led to the discovery of ribbon-shaped ferroelectric supramolecular assemblies that are thermodynamically stable with their long axes parallel to both the preferred hydrogen-bonding direction of ß-sheets and the bistable polar axes of VDF hexamers. Relative to a commonly used ferroelectric copolymer, the biomolecular assemblies exhibit a coercive field that is two orders of magnitude lower, as the result of supramolecular dynamics, and a similar level of remnant polarization, despite having a peptide content of 49 wt%. Furthermore, the Curie temperature of the assemblies is about 40 °C higher than that of a copolymer containing a similar amount of VDF. This supramolecular system was created using a biologically inspired strategy that is attractive in terms of sustainability and that could lead to new functions for soft ferroelectrics.

Surfactant-Assisted Wet Granulation-Based Matrix Tablets without Exceptional Additives: Prolonging Systemic Exposure of Model BCS Class II Ketoprofen.

The present study was aimed to ameliorate the issue of solubility and thereby, bioavailability of ketoprofen, a BCS Class II drug. The sustained release matrix tablets (MT) were prepared using surfactant-assisted wet granulation (SAWG) with 1-5% of different surfactants. The tablet characteristics were within the compendial limits. The selected sustained release-compliant matrix tablet formulation containing granules prepared using 3% Soluplus® (MT2) released the drug by swelling-erosion. In human volunteers, MT2 attained the maximum plasma concentration (Cmax) of 5.72µg /ml ± 0.30 h, time to Cmax (Tmax) of 5.56 ± 0.30 h and maintained the plasma concentration above its minimum effective concentration (MEC), 0.7 µg.ml-1 till 24h. A control formulation, prepared from granules without surfactant (MT16), promptly attained Cmax of 9.62 ± 0.76 µg/ml within 1h but rapidly declined to below MEC in 8h. Area under the curve from initial point to infinity (AUC0-∞) of MT2 (78.65 ± 7.64 µg.h.ml-1) was 2.29 folds higher than 34.39 ± 3.06 µg.h.ml-1 of MT16. With decreased Cmax, increased AUC0-∞, delayed Tmax and retained ketoprofen concentration above MEC for longer time, MT2 corresponded with the in-vitro sustained drug release characteristic. There is a likelihood of administration of once-a-day single dose of MT2 without plasma fluctuations, expected from two doses of MT16. SAWG helped developing a swellable-erodible sustained release matrix tablet formulation of ketoprofen with the desired biopharmaceutical and pharmacokinetics properties, merely by addition of Soluplus® in granules and without incorporation of any special ingredients or the major manipulation of the formulative ingredients in the formulation.

Enhancing sports mouthguards with PLA + and PC: stress reduction, energy absorption, and topology optimization.

OBJECTIVES: The objective of this paper was to compare the effectiveness of different materials for mouthguards in preventing oral and maxillofacial injuries during sports activities. The present study compares the stress-reduction and energy absorption capabilities of two other fused filament materials - poly(lactic-acid plus) (PLA+) and polycarbonate (PC), with Ethylene-vinyl acetate (EVA), which is the most commonly used material for mouthguard fabrication. MATERIALS AND METHODS: Two human skulls were modelled, and a boxing glove simulated punches along the x, y, and z-axes with 5 mm displacement with 1 kN force. Firstly, the maximum principal stress curve in the skull was compared for forces along the three perpendicular directions. Furthermore, the present study examines materials energy absorption properties, including their specific energy absorption characteristics and initial peak von Mises stresses. Additionally, a topology optimization approach is used to create an alternative design for a mouthguard to improve specific energy absorption. RESULTS: The model without a mouthguard showed the highest stress concentration of 32.298 MPa in the teeth, followed by the EVA material, which resulted in a maximum principal stress of 28.525 MPa. Fused filament 3D materials, such as PLA + and PC, on the other hand, showed better mechanical effectiveness in both lower jaw dislocation and lower maximum principal stress by 30.82% and 51.25% in the mandibular and maxillary teeth. Though EVA comparatively shows better specific energy absorption capability at 2.24 kJ/kg post-optimization than PLA + and PC, the peak principal stress experienced in the mandibular region was comparatively higher. The topology optimization, however, improved the energy-absorbing capabilities of PLA + by 4.5 times, reaching 1.37 kJ/kg and PC from 0.165 kJ/kg to 0.38 kJ/kg. CONCLUSIONS: This study demonstrates that PLA + and PC have better stress reduction capabilities than EVA and could be promising materials for the fabrication of mouthguards in sports activities. This study highlights the importance of topology optimization in dental materials science and engineering to develop safer and more effective mouthguard designs.

Framework's marginal adaptation evaluation of fixed partial denture using conventional and digital impression techniques.

PURPOSE: To evaluate the marginal and internal misfit of fixed partial denture zirconia frameworks developed from conventional impression and intraoral scanning, before and after being subjected to the thermal cycle of the covering ceramic. METHODS: A three-elements fixed partial denture was prepared, molded, and poured with polyurethane. Group CI (n= 7) was impressed by the conventional technique with polyvinyl siloxane material, and the plaster models scanned on the inEosX5 bench scanner. Group DI (n=07) was scanned using the CEREC Bluecam intraoral scanner. The models and images obtained were sent to the laboratory and the frameworks were made using zirconia blocks. After this, they were subjected to the ceramic thermal cycle, simulating the ceramic application. Marginal and internal misfits of the frameworks were measured before (T1) and after (T2) thermal cycle simulation using the replica technique in an optical microscope. Statistical analysis was performed using the mixed effects of linear model tests and comparisons. RESULTS: There were no statistical differences for axial misfit. Significant differences were found between the groups for occlusal, vertical, horizontal, and absolute misfit, where group CI had higher values than group DI (P< 0.001). At the time, there was a statistical difference only in the absolute misfit, where T1 had lower values than T2. The misfit in group CI was greater than in group DI; however, the average misfit values found are low and considered clinically acceptable. CLINICAL SIGNIFICANCE: Knowing marginal and internal misfit is an important step to consolidating digital impressions in fixed partial dentures, implying a secure use of this technique.

Core-Shell PEDOT-PVDF Nanofiber-Based Ammonia Gas Sensor with Robust Humidity Resistance.

Current ammonia sensors exhibit cross-sensitivity to water vapor, leading to false alarms. We developed a core-shell nanofiber (CSNF) structure to address these issues, using conductive poly(3,4-ethylenedioxythiophene) (PEDOT) as the core and hydrophobic polyvinylidene fluoride-tetrafluoroethylene (PVDF-TrFE) as the shell. The PEDOT-PVDF CSNF, with a diameter of ~500 nm and a 300 nm thick PVDF layer, showed a superior sensitivity and humidity resistance compared to conventional PEDOT membranes for ammonia concentrations of 10-100 ppm. In humid environments, CSNF sensors outperformed membrane sensors, exhibiting a tenfold increase in performance at 51% relative humidity (RH). This study highlights the potential of CSNF sensors for practical ammonia detection, maintaining a high performance under varying humidity levels.

Assemblable 3D biomimetic microenvironment for hMSC osteogenic differentiation.

Adequate simulation mimicking a tissue's native environment is one of the elemental premises in tissue engineering. Although various attempts have been made to induce human mesenchymal stem cells (hMSC) into an osteogenic pathway, they are still far from widespread clinical application. Most strategies focus primarily on providing a specific type of cue, inadequately replicating the complexity of the bone microenvironment. An alternative multifunctional platform for hMSC osteogenic differentiation has been produced. It is based on poly(vinylidene fluoride) (PVDF) and cobalt ferrites magnetoelectric microspheres, functionalized with collagen and gelatin, and packed in a 3D arrangement. This platform is capable of performing mechanical stimulation of piezoelectric PVDF, mimicking the bones electromechanical biophysical cues. Surface functionalization with extracellular matrix biomolecules and osteogenic medium complete this all-round approach. hMSC were cultured in osteogenic inducing conditions and tested for proliferation, surface biomarkers, and gene expression to evaluate their osteogenic commitment.

Sensitive Detection of Histones and γ-H2AX by Immunoblotting: Problems and Solutions.

Histones and their posttranslational modifications (PTMs) are critical regulators of gene expression. Differentiation, environmental stressors, xenobiotics, and major human diseases cause significant changes in histone variants and PTMs. Western blotting is the mainstay methodology for detection of histones and their PTMs in the majority of studies. Surprisingly, despite their high abundance in cells, immunoblotting of histones typically involves loading of large protein amounts that are normally used for detection of sparse cellular proteins. We systematically examined technical factors in the Western-blotting-based detection of human histones with >30 antibodies. We found that under multiple protein transfer conditions, many histone epitopes on polyvinylidene fluoride (PVDF) membranes had a very low antibody accessibility, which was dramatically increased by the addition of a simple denaturation step. Denaturation of membrane-bound proteins also enhanced the specificity of some histone antibodies. In comparison to standard PVDF membranes, the sensitivity of histone detection on standard nitrocellulose membranes was typically much higher, which was further increased by the inclusion of the same denaturation step. Optimized protocols increased by >100-times detection sensitivity for the genotoxic marker γ-H2AX with two monoclonal antibodies. The impact of denaturation and nitrocellulose use varied for different histones, but for each histone, it was generally similar for antibodies targeting N-terminal and C-terminal regions. In summary, denaturation of membrane-bound histones strongly improves their detection by Westerns, resulting in more accurate measurements and permitting analyses with small biological samples.

Enhanced antibacterial efficacy: rapid analysis of silver-decorated azithromycin-infused Soluplus® nanoparticles against E. coli and S. epidermidis biofilms.

The escalating threat of antibiotic-resistant bacterial biofilms necessitates innovative antimicrobial strategies. This study introduces silver-decorated azithromycin-infused Soluplus® nanoparticles (Ag-AZI-Sol NPs) synthesized via a controlled emulsion diffusion method to ensure sustained release of antimicrobial silver ions for over six hours-a critical factor for continuous antibacterial efficacy. The efficacy of these nanoparticles was evaluated against biofilms formed by Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis), pathogens that cause hospital-acquired infections. Concentrations of 5 and 10 µg mL-1 of Ag-AZI-Sol NPs induced significant morphological changes within the biofilms, disrupting the bacterial extracellular matrix as observed using scanning electron microscopy (SEM). This disruption peaked between two and six hours, coinciding with damage to bacterial cells by the silver ions. Antibacterial assay measurements confirmed a significant reduction in the growth rate among the Ag-AZI-Sol NP-treated bacteria compared with controls. Electrochemical analysis using laser-induced graphene (LIG) and chronoamperometry revealed a decline in current, indicating an effective antibacterial effect. This innovative biosensing technique makes use of the high conductivity and surface area of LIG to detect changes in bacterial activity quickly and sensitively. Our findings highlight the potent microbicidal properties of Ag-AZI-Sol NPs and suggest diverse applications from food processing to medical device coatings.

Under Water Superelastic Porous Nanofibrous Sponge for Efficient RNA Separation and Purification.

Developing monolithic materials for chromatography columns with a novel interconnected porous structure is vital for the enhancement of the separation efficiency of RNA purification processes. Herein, a porous nanofibrous sponge (PNFS) is constructed by freeze molding and freeze-drying a nanofiber dispersion with ethylene vinyl alcohol copolymer nanofibers as the skeleton, chitosan (CS) and polyethylenimine (PEI) as the binders, and glutaraldehyde (GA) as the crosslinking agent. The results show that when the CS content of the dispersion is 1.5 wt %, PNFS demonstrates a high static adsorption capacity of 406.5 mg/g (30.7 mg/m2) and a dynamic adsorption capacity of 382.6 mg/g (28.9 mg/m2) at a flow rate of 1 mm/min. Moreover, PNFS shows a high specific adsorption performance toward RNA in the presence of bovine serum albumin, lecithin, or DNA by adjusting the solution pH value and the method of gradient elution. Besides, PNFS presents exceptional performance in the rapid separation of RNA from HT22 cells without degradation. This result can be attributed to optimized morphology, pore structure, and comprehensive performance of PNFS, benefiting from the synergistic effect of the highly oriented porous structure and CS-PEI interaction derived from the high-density adsorption ligands on the channel walls of PNFS. This work provided an efficient strategy to handle the permeability/adsorptivity trade-off for ion-exchange chromatographic materials.

Highly stretchable nanocomposite piezofibers: a step forward into practical applications in biomedical devices.

High-performance biocompatible composite materials are gaining attention for their potential in various fields such as neural tissue scaffolds, bio-implantable devices, energy harvesting, and biomechanical sensors. However, these devices currently face limitations in miniaturization, finite battery lifetimes, fabrication complexity, and rigidity. Hence, there is an urgent need for smart and self-powering soft devices that are easily deployable under physiological conditions. Herein, we present a straightforward and efficient fabrication technique for creating flexible/stretchable fiber-based piezoelectric structures using a hybrid nanocomposite of polyvinylidene fluoride (PVDF), reduced graphene oxide (rGO), and barium-titanium oxide (BT). These nanocomposite fibers are capable of converting biomechanical stimuli into electrical signals across various structural designs (knit, braid, woven, and coil). It was found that a stretchable configuration with higher output voltage (4 V) and a power density (87 µW cm-3) was obtained using nanocomposite coiled fibers or knitted fibers, which are ideal candidates for real-time monitoring of physiological signals. These structures are being proposed for practical transition to the development of the next generation of fiber-based biomedical devices. The cytotoxicity and cytocompatibility of nanocomposite fibers were tested on human mesenchymal stromal cells. The obtained results suggest that the developed fibers can be utilized for smart scaffolds and bio-implantable devices.

Hot Melt Extruded High-Dose Amorphous Solid Dispersions Containing Lumefantrine and Soluplus.

Over the last 15 years, a small number of paediatric artemisinin-based combination therapy products have been marketed. These included Riamet® and Coartem® dispersible tablets, a combination of artemether and lumefantrine, co-developed by the Medicines for Malaria Venture and Novartis. Disappointingly, patient compliance, requirement for high-fat meal, and sporadic drug dissolution behaviours following administration still result in considerable challenges for these products. The first and foremost barrier that needs addressed for successful delivery of the artemether/lumefantrine combination is the poor solubility of lumefantrine within the gastrointestinal fluids. In this work, amorphous solid dispersions of lumefantrine within Soluplus®-based matrices have been manufactured using hot melt extrusion as a potential formulation strategy to achieve enhanced dissolution and apparent solubility. The drug loading capacity of Soluplus® to accommodate amorphous lumefantrine, whilst ensuring improved in-vitro dissolution performance, was investigated. The extrusion process employed a variety of processing parameters, including various temperature profiles and different production scales. The influence of variation in extrusion conditions upon the physical stability of manufactured amorphous solid dispersions was also examined. This allowed for a greater understanding of the role of extrusion processing conditions on the performance of supersaturated amorphous solid dispersions during dissolution and storage. This may allow for the design and manufacture of drug enabled formulations with lower drug dosing and thus a lower risk of adverse effects.

Piezoelectric PVDF and its copolymers in biomedicine: innovations and applications.

In recent years, poly(vinylidene fluoride) (PVDF) has emerged as a versatile polymer with a wide range of applications across various fields. PVDF's piezosensitivity, versatility, crystalline structure, and tunable parameters have established it as a highly sought-after material. Furthermore, PVDF and its copolymers exhibit excellent processability and chemical resistance to a diverse array of substances. Of particular significance is its remarkable structural stability in physiological media, which highlights its potential for use in the development of biomedical products. This review offers a comprehensive overview of the latest advancements in PVDF-based biomedical systems. It examines the fabrication of stimulus-responsive delivery systems, bioelectric therapy devices, and tissue-regenerating scaffolds, all of which harness the piezosensitivity of PVDF. Moreover, the potential of PVDF in the fabrication of both invasive and non-invasive diagnostic tools is investigated, with particular emphasis on its flexibility, transparency, and piezoelectric efficiency. The material's high biocompatibility and physiological stability are of paramount importance in the development of implantable sensors for long-term health monitoring, which is crucial for the management of chronic diseases and postoperative care. Additionally, we discuss a novel approach to photoacoustic microscopy that employs a PVDF sensor, thereby eliminating the necessity for external contrast agents. This technique provides a new avenue for non-invasive imaging in biomedical applications. Finally, we explore the challenges and prospects for the development of PVDF-based systems for a range of biomedical applications. This review is distinctive in comparison to other reviews on PVDF due to its concentrated examination of biomedical applications, including pioneering imaging techniques, long-term health monitoring, and a detailed account of advancements in the field. Collectively, these elements illustrate the potential of PVDF to markedly influence biomedical engineering and patient care, distinguishing it from existing literature. By leveraging the distinctive attributes of PVDF and its copolymers, researchers can continue to advance the frontiers of biomedical engineering, with the potential to transform patient care and treatment outcomes.

High-loading ficin@AuNPs on polymer-UiO-66 surface with enhanced peroxidase-mimetic catalytic activity for colourimetric detection of dopamine.

Recently, MOFs@AuNPs composites-based catalysts via anchoring of AuNPs onto metal-organic-frameworks (MOFs) have attracted great attention. However, the influence of the AuNPs loading amounts on the catalytic activity of MOFs@AuNPs composites remains largely unexplored. Here, ficin (Fic) protected AuNPs (Fic@AuNPs) anchored onto the surface of UiO-66-NH2 (UiO) modified with poly(2-vinyl-4,4-dimethyl-2-oxazolidine) (PV) were designed and constructed. The UiOPVFic@AuNPs composites with longer PV chains leading to high-loading Fic@AuNPs exhibited intense peroxidase (POD)-mimetic activity in 3,3'5,5'-tetramethylbenzidine (TMB) oxidation. Further, following the colour-fading, dopamine (DA) was sensitively and selectively monitored in the composites-TMB-H2O2 system. The portable smartphone sensing platform-based colourimetric method had good linearity ranging from 3.34 to 36.7 µM (R2 = 0.995), with a limit of detection of 0.3 µM. This protocol explores high-loading AuNPs on polymer-MOFs composites, providing deep insights into understanding catalytic activity improvements of polymer-MOFs@AuNPs catalysts and revealing their application potential in real biological samples analysis.

Encapsulation of astaxanthin in OSA-starch based amorphous solid dispersions with HPMCAS-HF/Soluplus® as effective recrystallization inhibitor.

In this study, the interaction among multifunctional excipients, including polysaccharides, cellulose derivatives, and surfactants, was particularly investigated, together with its impact on the physicochemical properties of astaxanthin amorphous solid dispersions (ASTX ASDs). It was indicated that Span 20 could rapidly form hemimicelles or aggregates in the presence of hypromellose acetate succinate HF (HPMCAS-HF, HF) or Soluplus®, while octenyl succinic anhydride modified starch (OSA-starch) efficiently assisted in the coalescence inhibition of drug-excipients aggregates, which was jointly beneficial to the recrystallization inhibition of amorphous ASTX. ASTX ASDs were further prepared with OSA-starch, HPMCAS-HF/Soluplus®, and Span 20 as the wall materials. DSC, SEM, and XRD confirmed that crystalline ASTX had transformed to amorphous state in the ASDs, while FT-IR spectra provided evidence suggesting the existence of hydrogen bonds and hydrophobic interaction between ASTX and the excipients. The dissolution of ASTX ASDs in different media revealed significant promotion, while the pharmacokinetic results further demonstrated the oral bioavailability of ASTX ASDs enhanced remarkably, exhibiting 2.75-fold (SD1) and 1.87-fold (SD2) increase, respectively, compared to ASTX bulk powder. In summary, the cellulose derivatives-surfactant interaction had great impact on the physicochemical properties of ASTX ASDs, and their combinations exhibited great potential for delivering the hydrophobic bioactive compounds efficiently.

Aligned Fibroporous Matrix Generated from a Silver Ion and Graphene Oxide-Incorporated Ethylene Vinyl Alcohol Copolymer as a Potential Biomaterial for Peripheral Nerve Repair.

Developing an ideal nerve conduit for proper nerve regeneration still faces several challenges. The attempts to fabricate aligned substrates for neuronal growth have enhanced the hope of successful nerve regeneration. In this wok, we have attempted to generate an electrospun matrix with aligned fibers from a silver and graphene oxide-incorporated ethylene vinyl alcohol copolymer (EVAL). The presence of silver was analyzed using UV-visible spectra, XPS spectra, and ICP. Raman spectra and FTIR spectra confirmed the presence of GO. The complexation of Ag+ with - OH of EVAL enabled the generation of aligned fibers. The fiber diameter (>1 µm) provided sufficient space for forming focal adhesion by the neurites and filopodia of N2a and C6 cells, respectively. The fiber diameter enabled the neurites and filopodia of the cells to align on the fibers. The incorporation of GO has contributed to the cell-material interactions. The morphological and mechanical properties of fibers obtained in the study ensure that the EVAL-Ag-GO-0.01 matrix is a potential substrate for developing a nerve guidance conduit/nerve wrap (NGC/W).

Accuracy of polyether and vinylpolysiloxane impressions when using different types of 3D-printed impression trays - an in vitro study.

OBJECTIVES: To investigate dimensional accuracy of polyether (PE) and vinylpolysiloxane (VPS) impressions taken with manually fabricated and 3D-printed trays. MATERIALS AND METHODS: To evaluate impression accuracy, highly precise digital data of a metallic lower jaw model with prepared teeth (regions 34 and 36), an implant (region 47) and three precision balls placed occlusally along the dental arch served as reference. PE (Impregum, 3M Oral Care) and VPS (Aquasil, Dentsply Sirona) impressions (n = 10/group) were taken with trays fabricated using different materials and manufacturing techniques (FDM: filament deposition modeling, material: Arfona Tray, Arfona; printer: Pro2, Raise3D; DLP: digital light processing, material: V-Print Tray, VOCO, printer: Max, Asiga; MPR: manual processing with light-curing plates, material: LC Tray, Müller-Omicron) including an open implant impression. Scans of resulting stone models were compared with the reference situation. Global distance and angular deviations as well as local trueness and precision for abutment teeth and scan abutment were computed. Possible statistical effects were analyzed using ANOVA. RESULTS: Clinically acceptable global accuracy was found (all mean absolute distance changes < 100 µm) and local accuracy for single abutments was excellent. All factors (abutment type, impression material, tray material) affected global accuracy (p < 0.05). In particular with PE impressions, MPR trays led to the best accuracies, both in horizontal and vertical direction. CONCLUSIONS: Within the limitations of this in vitro study, impression accuracy was high in use of both polyether and vinylpolysiloxane combined with different 3D-printed and customized trays making them recommendable for at least impressions for smaller fixed dental prostheses. Manually fabricated trays were overall still the best choice if utmost precision is required. CLINICAL RELEVANCE: Based on the results of this study, use of innovative CAD-CAM fabrication of individual impression trays fulfills the perquisites to be a viable option for impression making. In the sense of translational research, performance should be proved in a clinical setting.

ZIF-67@polyvinylidene fluoride mixed matrix membranes towards improved hydrogen separation performance.

This work is primarily focused on overcoming the limitations of polymeric membranes in achieving the balance between permeability and selectivity of the separation performance. The filler, Zeolitic imidazole framework -67 (ZIF-67) nanoparticles were synthesised in cubical morphology using hexadecyltrimethylammonium bromide (CTAB) as a surfactant via the wet-chemical method. The uniform particles with particle sizes ranging between 120-180 nm were incorporated into the polyvinylidene fluoride (PVDF) matrix to fabricate mixed matrix membranes via the phase inversion method. These mixed matrix membranes were systematically characterised to confirm the chemical, structural and morphological properties of the materials and membranes. Furthermore, the membranes showed a 56.5% improvement in their mechanical properties. The results confirm that 5 wt.% ZIF-67/PVDF membrane showed the best separation results compared to its pure counterpart. The permeability of H2 gas was reported to be 1,094,511 Barrer, with selectivities of 3.03 for H2/CO2 and 3.06 for H2/N2. This represents a 210.6% increase in the permeability of H2 gas. These results demonstrate the influence of ZIF-67 loading in the PVDF polymer matrix along with the potential of ZIF-67/PVDF mixed matrix membranes in the field of hydrogen separation and purification.

Synthesis of Well-Defined Poly(vinyl alcohol-co-vinyl acetate) Copolymers by Alcoholysis of Poly(vinyl acetate) Synthesized by Macromolecular Design via Interchange of Xanthate Polymerization, and Their Use as a Stabilizer in Emulsion (Co)polymerization of Vinyl Acetate.

This work aims at synthesizing tailor-made poly(vinyl alcohol-co-vinyl acetate) (PVA) amphiphilic copolymers, obtained by alcoholysis of poly(vinyl acetate) (PVAc) that could display improved properties as stabilizers compared to commercially available PVAs. Well-defined PVAs with different alcoholysis degrees were produced from a library of PVAc homopolymers synthesized by macromolecular design via interchange of xanthate polymerization and exhibiting different degrees of polymerization degrees. Subsequently, these PVAs were evaluated as stabilizers in the emulsion copolymerization of VAc and vinyl neodecanoate (VERSA 10, referred to as V10) and compared to a commercially available reference PVA obtained by alcoholysis of PVAc formed by conventional radical polymerization. In all cases, stable latexes were obtained and compared in terms of their colloidal characteristics. To identify the best stabilizer candidate, the amount of PVA remaining in water and not participating to the particle stabilization was evaluated in each case.

Catechol-Fe(III) complexes modified PVDF membrane for hazardous pollutants separation and antifouling properties.

Organic pollutants, such as toluene and xylene, in industrial wastewater negatively impact the environment. Membrane treatment is one of the best methods to reduce impurities in wastewater. Existing membranes that coat the water surface with hydrophilic material only effectively resist the initial fouling, resulting in poor oil and water selectivity. Here we report a simple and efficient method to enhance the water flux and antifouling properties of polyvinylidene fluoride (PVDF) membranes. This method involves developing and applying Catechol-Fe(III) complexes with a rough surface to the PVDF surface. Forming Catechol-Fe(III) complexes on the surface better anchors them to the membrane than the dip-coating method. The PVDF membranes with rough Catechol-Fe(III) complexes are superoleophobic, with an oil contact angle of 152 ° and high permeability, with pure water flux of 10487 Lm-2h-1bar-1 and 1 wt% toluene in water emulsion flux of 4697 Lm-2h-1bar-1. Overall, the straightforward manufacturing process, increased permeability, and outstanding antifouling capabilities of the PVDF membrane incorporating rough nanoparticles offer promising prospects for designing and implementing suitable membranes for oil in water emulsion separation applications.