Porous Polymeric Materials Research Articles

Nanosecond pulsed discharge plasma modified porous polymer adsorbent materials for efficient removal of low‐concentration bisphenol A in liquid

AbstractThe efficient removal of low‐concentration endocrine disruptors is crucial for the protection of the aquatic environment. In this study, porous polymer adsorbent materials were modified by nanosecond pulsed discharge plasma to achieve efficient adsorption of low‐concentration bisphenol A (BPA). The removal efficiency of BPA reached 99% after 10 min of plasma modification at a pulse peak voltage of 28 kV, which increased by 25.8% compared to the raw materials. This enhancement was attributed to the increase of active sites and oxygen‐containing functional groups. The adsorption behaviors of the porous polymer materials were primarily dominated by monolayer chemisorption. Subsequently, comparative experiments further verified the high‐efficiency adsorption performance of porous polymer materials after plasma treatment.

Specifics of Porous Polymer and Xenogeneic Matrices and of Bone Tissue Regeneration Related to Their Implantation into an Experimental Rabbit Defect.

This paper provides a study of two bone substitutes: a hybrid porous polymer and an osteoplastic matrix based on a bovine-derived xenograft. Both materials are porous, but their pore characteristics are different. The osteoplastic matrix has pores of 300-600 µm and the hybrid polymer has smaller pores, generally of 6-20 µm, but with some pores up to 100 µm across. SEM data confirmed the porometry results and demonstrated the different structures of the materials. Therefore, both materials were characterized by an interconnected porous structure and provided conditions for the adhesion and vital activity of human ASCs in vitro. In an experimental model of rabbit shin bone defect, it was shown that, during the 6-month observation period, neither of the materials caused negative reactions in the experimental animals. By the end of the observation period, restoration of the defects in animals in both groups was completed, and elements of both materials were preserved in the defect areas. Data from morphological examinations and CT data demonstrated that the rate of rabbit bone tissue regeneration with the hybrid polymer was comparable to that with the osteoplastic matrix. Therefore, the hybrid polymer has good potential for use in further research and improvement in biomedical applications.

Polyrotaxanated covalent organic frameworks based on β-cyclodextrin towards high-efficiency synergistic inactivation of bacterial pathogens

As an emerging artificial porous material, covalent organic frameworks (COFs) with customizable structure and function, have always been the focus of polymer science. Controllable fabrication of COFs with brand-new structure is the top priority for its development. Here, the ‘supramolecular binding’ strategy is developed as a simple but efficient method to prepare COFs with novel structures and functions. By this means, polymeric rotaxanes threaded COFs, denoted as Por-CD-COF, was facilely prepared via the combination of dynamic covalent imine-bond formation with supramolecular self-assembly, in which the polyrotaxane formed via inclusion of aromatic linker with bactericidal active β-cyclodextrin macrocycle (CD) was condensed with the photosensitive porphyrin via the combination of mechanical grinding and solvothermal synthesis. The formation of polyrotaxane could change the distance between layers, avoiding the quench of photoactivity caused by the severe aggregation of layered structure. Under the same molar amount of reaction monomers, the weight of the Por-CD-COF is approaching five times of the CD-free COF, which could greatly reduce the use of photoactive ingredients. Further experiments demonstrated the introduction of CDs could also significantly improve the biocompatibility. Impressively, this special porphyrin-involved CD-COF, displays excellent photo activity, which could act as an efficient broad spectrum antibacterial agents realizing the combinational action of cyclodextrin enhanced photothermal and photodynamic antimicrobial at an extremely low quality of the effective photosensitizer (Porphyrin). Meanwhile, even at the same dose of fungicide, the bactericidal effect of Por-CD-COF is far exceeding the CD-free therapeutic agent. This novel synthetic strategy allows the incorporation of mechanically interlocked CDs (MIMs) into the porous polymeric materials, providing an easy access to low-cost preparation of COFs for the specific applications.

Machine Learning in Membrane Design: From Property Prediction to AI-Guided Optimization.

Porous membranes, either polymeric or two-dimensional materials, have been extensively studied because of their outstanding performance in many applications such as water filtration. Recently, inspired by the significant success of machine learning (ML) in many areas of scientific discovery, researchers have started to tackle the problem in the field of membrane design using data-driven ML tools. In this Mini Review, we summarize research efforts on three types of applications of machine learning in membrane design, including (1) membrane property prediction using ML, (2) gaining physical insight and drawing quantitative relationships between membrane properties and performance using explainable artificial intelligence, and (3) ML-guided design, optimization, or virtual screening of membranes. On top of the review of previous research, we discuss the challenges associated with applying ML for membrane design and potential future directions.

Porous polypropylene produced by phase separation for high solar reflectivity and passive cooling

Passive cooling techniques have gained widespread use in everyday life and various industries by utilizing sunlight reflection to cool objects without requiring additional energy input. Porous polymer materials possess the unique ability to provide both thermal insulation and solar reflection due to their inherent multiphase structure. In this study, we developed a porous polypropylene (PP) with a hierarchically structured surface layer using a simple and efficient solvent treatment method based on recrystallization. As a result, the porous structure and hierarchically structured surface significantly increase the solar reflectance from 11 to 86%. We found that by manipulating the recrystallization process and using reflective additives, solar reflectivity can be further improved. With the use of TiO2 and BaSO4 additives, a solar reflectance of 90% was achieved, while a solar reflectance of 93% was achieved with nucleating agents. In practical terms, these improvements result in significant temperature reductions in cooling performance tests compared to extruded PP sheets: 17, 19, and 22 °C for porous PP, porous PP/TiO2 or PP/BaSO4, and porous nucleated PP, respectively. The modification method introduced could help PP offer new possibilities for developing low-cost chemically resistant and thermally insulating layers in thermal management applications.

Highly Flexible and Sensitive Pressure Sensor: Fabrication of Porous PDMS/Graphene Composite via Laser Thermoforming

AbstractFlexible pressure sensors employing porous polymer materials are renowned for their superior sensing capabilities, attributed to the inherently low stiffness of porous polymers. The practical utilization of such sensors hinges on the development of a straightforward, cost‐effective, and patternable method for preparing porous polymer materials. In this research, a novel laser thermoforming process is introduced to craft a porous Polydimethylsiloxane (PDMS) film, leveraging carbon black (CB) as an endothermic agent and glucose as a porogen. The resulting porous PDMS film serves as the foundation for a remarkably sensitive flexible piezoresistive sensor. Owing to the inherent flexibility endowed by the porous structure, the porous PDMS‐based pressure sensor achieves a remarkable sensitivity of 109.4 kPa−1 within 0–200 Pa, an effective measurement span of 0–100 kPa, rapid response and recovery times of 79 and 55 ms, and impressive stability over 5000 cycles. The sensor's utility extends to applications such as human pulse monitoring, Morse coding, and robot claw sensing, underscoring its promise in the realm of flexible electronics. In summary, the laser thermoforming process realizes the one‐step, economical, and patternable preparation of porous polymer materials, and introduces a novel avenue for the realization of high‐performance flexible sensors based on thermally cured porous polymers.

Features of Changes in the Structure and Properties of a Porous Polymer Material with Antibacterial Activity during Biodegradation in an In Vitro Model.

Hybrid porous polymers based on poly-EGDMA and polylactide containing vancomycin, the concentration of which in the polymer varied by two orders of magnitude, were synthesized. The processes of polymer biodegradation and vancomycin release were studied in the following model media: phosphate-buffered saline (PBS), trypsin-Versene solution, and trypsin-PBS solution. The maximum antibiotic release was recorded during the first 3 h of extraction. The duration of antibiotic escape from the polymer samples in trypsin-containing media varied from 3 to 22 days, depending on the antibiotic content of the polymer. Keeping samples of the hybrid polymer in trypsin-containing model media resulted in acidification of the solutions-after 45 days, up to a pH of 1.84 in the trypsin-Versene solution and up to pH 1.65 in the trypsin-PBS solution. Here, the time dependences of the vancomycin release from the polymer into the medium and the decrease in pH of the medium correlated. These data are also consistent with the results of a study of the dynamics of sample weight loss during extraction in the examined model media. However, while the polymer porosity increased from ~53 to ~60% the pore size changed insignificantly, over only 10 μm. The polymer samples were characterized by their antibacterial activity against Staphylococcus aureus, and this activity persisted for up to 21 days during biodegradation of the material, regardless of the medium type used in model. Surface-dependent human cells (dermal fibroblasts) adhere well, spread out, and maintain high viability on samples of the functionalized hybrid polymer, thus demonstrating its biocompatibility in vitro.

Covalent Organic Frameworks as Electrode Materials for Alkali Metal-ion Batteries.

Covalent organic frameworks (COFs) are a class of porous crystalline polymeric materials constructed by linking organic small molecules through covalent bonds. COFs have the advantages of strong covalent bond network, adjustable pore structure, large specific surface area and excellent thermal stability, and have broad application prospects in various fields. Based on these advantages, rational COFs design strategies such as the introduction of active sites, construction of conjugated structures, and carbon material composite, etc. can effectively improve the conductivity and stability of the electrode materials in the field of batteries. This paper introduces the latest research results of high-performance COFs electrode materials in alkali metal-ion batteries (LIBs, SIBs, PIBs and LSBs) and other advanced batteries. The current challenges and future design directions of COFs-based electrode are discussed. It provides useful insights for the design of novel COFs structures and the development of high-performance alkali metal-ion batteries.

Covalent organic polyrotaxanes based on β-cyclodextrin for iodine capture.

Herein, covalent organic polyrotaxanes (COPRs) were integrated with supermolecule self-assembly and dynamic imine bond formation to act as absorbents that captured radioactive iodine from water. The aromatic building blocks were initially complexed with β-cyclodextrin (β-CD) to form pseudorotaxanes, which were then condensed with aromatic tri-aldehyde via mechanical grinding and solvothermal synthesis in sequence. The threading of β-CD throughout the polymer skeleton effectively reduced the usage of expensive building blocks and significantly lowered the cost, while also remarkably enhancing the skeleton polarity, which is closely related to many special applications. Impressively, the threading of CD improved the water dispersibility of COPRs, which displayed an abnormally high iodine adsorption capacity. This novel synthetic strategy allows the incorporation of mechanically interlocked CDs into porous polymeric materials, which provides access to low-cost preparations of COPRs with a brand new structure for specific applications.

On the use of neural networks for the structural characterization of polymeric porous materials

The structural characterization is an essential task in the study of porous materials. To achieve reliable results, it requires to evaluate images with hundreds of pores. Current methods require large time amounts and are subjected to human errors and subjectivity. A completely automatic tool would not only speed up the process but also enhance its reliability and reproducibility. Therefore, the main objective of this article is the study of a deep-learning-based technique for the structural characterization of porous materials, through the use of a convolutional neural network. Several fine-tuned Mask R–CNN models are evaluated using different training configurations in four separate datasets each composed of numerous SEM images of diverse polymeric porous materials: closed-pore extruded polystyrene (XPS), polyurethane (PU), and poly(methyl methacrylate) (PMMA), and open-pore PU. Results prove the tool capable of providing very accurate results, equivalent to those achieved by time-consuming manual methods, in a matter of seconds.

Tribological behavior of lubricant-impregnated porous polyimide

Porous materials impregnated with lubricants can be used in conditions where limited lubricant is desirable. In this work, three porous polyimides (PPI) with different densities were prepared. Polyalphaolefin (PAO) impregnated PPI (iPPI) discs were rubbed against steel and sapphire balls. In operando observations of the iPPI–sapphire contacts show that oil is released under an applied load, forming a meniscus around contacts. Cavitation at the outlet is created at high sliding speeds. The amount of released oil increases with increasing PPI porosity. Contact moduli, E*, estimated based on the actual contact size show that trapped oil in iPPIs contributes to load support. At higher speeds, tribological rehydration of the contact occurs in low density iPPI, with that E* rises with speed. For high density PPIs, high speeds give a constantly high E* which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil exudation. Friction of iPPI–steel contacts is governed by the mechanical properties of the PPI, the flow of the lubricant, and the roughness of the PPI surfaces. For low- and medium- density (highly porous, high roughness) PPIs, large amount of oil is released, and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological rehydration. For high density (low porosity) PPI, with lower roughness, hydrodynamic lubrication is achieved which gives the lowest friction. Our results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness, stiffness, oil flow, and oil retentions.

Radiative transfer model and validation for infrared management optical properties of porous polymer materials incorporating impacts of micro-voids

In order to characterize the infrared (IR) radiation absorption and/or emission performances of functional porous polymers which claim to have healthcare functions due to IR excitation and emission by processing technologies, a radiative transfer model was constructed based on the principle of IR radiation, the Beer–Lambert law, the Fresnel’s formula and Planck’s law. The theoretical analysis was conducted for the IR management optical properties of the porous sheet polymer materials, including IR reflection, transmission, absorption and emission behaviours during the dynamic process of IR radiation. A modeling method for characterization and revealing of IR management optical properties and optical and thermal transfer behaviours of the reflection and transmission was then investigated from the structural parameters and the temperature rise characteristics of the porous sheet polymer materials during the dynamic IR radiation process. The model was validated by comparing the predicted values from the radiative transfer model with the measured values from the test results of the validation experiments of eight typical porous sheet polymers in an experimental setup. The model was modified by consideration of the influences of two types of micro-voids defects represented by the porosity of micro structure and the thickness compression ratio. The micro-voids defects factors were added to the structural parameters, and therefore the model was improved and the maximum prediction errors of the transmission and reflection surfaces were mostly less than 10%. The radiative transfer model provides the theoretical fundamentals for the evaluation and guidance of IR management optical performances for new products design, development, fabrication and processing in industrial application of functional porous polymers.

Ultrapermeable Gel Membranes Enabling Superior Carbon Capture

AbstractMembrane technology is rapidly gaining broad attraction as a viable alternative for carbon capture to mitigate increasingly severe global warming. Emerging CO2‐philic membranes have become crucial players in efficiently separating CO2 from light gases, leveraging their exceptional solubility‐selectivity characteristics. However, economic and widespread deployment is greatly dependent on the boosted performance of advanced membrane materials for carbon capture. Here, we design a unique gel membrane composed of CO2‐philic molecules for accelerating CO2 transportation over other gases for ultrapermeable carbon capture. The molecular design of such soft membranes amalgamates the advantageous traits of augmented permeation akin to liquid membranes and operational stability akin to solid membranes, effectively altering the membrane's free volume characteristics validated by both experiments and molecular dynamics simulation. Surprisingly, gas diffusion through the free‐volume‐tuned gel membrane undergoes a 9‐fold improvement without compromising the separation factor for the superior solubility selectivity of CO2‐philic materials, and CO2 permeability achieves a groundbreaking record of 5608 Barrer surpassing the capabilities of nonfacilitated CO2 separation materials and exceeding the upper bound line established in 2019 even by leading‐edge porous polymer materials. Our designed gel membrane can maintain exceptional separation performance during prolonged operation, enabling the unparalleled potential of solubility‐selective next‐generation materials towards sustainable carbon capture.

Ultrapermeable Gel Membranes Enabling Superior Carbon Capture.

Membrane technology is rapidly gaining broad attraction as a viable alternative for carbon capture to mitigate increasingly severe global warming. Emerging CO2 -philic membranes have become crucial players in efficiently separating CO2 from light gases, leveraging their exceptional solubility-selectivity characteristics. However, economic and widespread deployment is greatly dependent on the boosted performance of advanced membrane materials for carbon capture. Here, we design a unique gel membrane composed of CO2 -philic molecules for accelerating CO2 transportation over other gases for ultrapermeable carbon capture. The molecular design of such soft membranes amalgamates the advantageous traits of augmented permeation akin to liquid membranes and operational stability akin to solid membranes, effectively altering the membrane's free volume characteristics validated by both experiments and molecular dynamics simulation. Surprisingly, gas diffusion through the free-volume-tuned gel membrane undergoes a 9-fold improvement without compromising the separation factor for the superior solubility selectivity of CO2 -philic materials, and CO2 permeability achieves a groundbreaking record of 5608 Barrer surpassing the capabilities of nonfacilitated CO2 separation materials and exceeding the upper bound line established in 2019 even by leading-edge porous polymer materials. Our designed gel membrane can maintain exceptional separation performance during prolonged operation, enabling the unparalleled potential of solubility-selective next-generation materials towards sustainable carbon capture.

Effects of graphene doping on shape stabilization, thermal energy storage and thermal conductivity properties of PolyHIPE/PEG composites

The development of clean and renewable energy sources has been necessitated by the ever-increasing energy consumption, increasing environmental degradation caused using fossil fuels and concerns over the rise in CO2 spreading. Functional phase change materials (PCMs)' energy storage capacity is appealing owing to their environmental friendliness, superior thermal energy storage (TES) capacity, and capability to improve energy efficiency. A series of hierarchical porous high internal phase emulsion polymer (PolyHIPE) materials with high PCM impregnation capacity were synthesized in this investigation. It has been achieved to encapsulate 80 % by mass of polyethylene glycol (PEG) into the PolyHIPE structure. However, the efficiency of energy storage and conversion systems is affected by a wide variety of factors; one of them is poor thermal conductivity. The development of carbon-based materials like graphene is particularly promising in the disciplines of energy storage and conversion. With this intention, the synthesis of composite PCMs in which the heat conductivity has been enhanced with graphene at three different ratios (wt% 3, 5, and 10) has been performed, conducting comprehensive investigations. The produced composite PCMs have an energy storage capability of over 120 J·g−1 and high thermal and structural stability. In the polyHIPE/graphene structures produced in the absence PCM, the thermal conductivity value exhibits a notable enhancement of up to 125 % due to the increased amount of graphene compared to the polyHIPE material. Following the impregnation of PolyHIPE@Graphene with PEG, it was observed that the thermal conductivity value improved by up to 51.2 % in comparison to PCM. The addition of graphene also gradually shortened the heat storage-release time. In short, herein a series of PCM composites with high energy storage capacity, capable of trapping different PCMs within their structure, has been proposed for TES applications. The manufactured composite PCMs have the potential to be used for a wide range of things, like maintaining the temperature of batteries and photovoltaic solar cells, packaging perishable foods, and providing thermal comfort in textiles and medicinal materials.

Study on mechanical properties and microstructure of porous organic polymer reinforced low-grade sand under wetting–drying cycles

Polymer materials are finding increasing application in soil stabilization, but little is known about the changes in performance and microstructure of polymer membranes under wetting–drying (W-D) cycles. This paper introduced a self-developed porous organic polymer material (SPOP) to investigate the mechanical properties of treated sand under various SPOP contents (1 %, 2 %, 3 %, and 4 %) and W-D cycles (0, 4, 8, 12, 16, and 20) using uniaxial compression tests and triaxial tests. The changes in the microstructure of SPOP-sand mixtures were observed by scanning electron microscope (SEM) and nuclear magnetic resonance (NMR). The results indicated that the addition of SPOP significantly increased the mechanical strength, elastic modulus, and cohesion of natural sand under W-D cycles. The mechanical properties exhibited an upward trend before decreasing as the increment of SPOP contents and peaked at 3 % SPOP content. Specimens with high SPOP content were more susceptible to moisture. On the other hand, the mechanical properties of SPOP-sand mixtures decreased significantly for all specimens under the first 4 cycles, followed by a decrease with increasing cycles exponentially. The NMR test showed the proportion of micropores within the specimens decreased by 27.81 %–48.09 % after wetting. The micropores were transformed into mesopores and macropores, and the porosity of specimens was increased. Based on the SEM images, there were three mechanisms of polymer strengthening sand, including wrapping, pore filling, and bridging effects. Alternate W-D cycles damaged the inter-particle bridging effect, thus weakening the bonding strength between the polymer membrane and sand particles. Soil aggregates inside the specimens were loosened, and polymer membrane was softened and broken under cyclic wetting and drying, causing the unstable structure of the specimen when applied external pressure.

Porous Polymer Materials in Triboelectric Nanogenerators: A Review.

Since the invention of the triboelectric nanogenerator (TENG), porous polymer materials (PPMs), with different geometries and topologies, have been utilized to enhance the output performance and expand the functionality of TENGs. In this review, the basic characteristics and preparation methods of various PPMs are introduced, along with their applications in TENGs on the basis of their roles as electrodes, triboelectric surfaces, and structural materials. According to the pore size and dimensionality, various types of TENGs that are built with hydrogels, aerogels, foams, and fibrous media are classified and their advantages and disadvantages are analyzed. To deepen the understanding of the future development trend, their intelligent and multifunctional applications in human-machine interfaces, smart wearable devices, and self-powering sensors are introduced. Finally, the future directions and challenges of PPMs in TENGs are explored to provide possible guidance on PPMs in various TENG-based intelligent devices and systems.

Synthesis of phenothiazine-based porous organic polymer and its application to iodine adsorption

At present, porous organic polymer materials (POPs) have become a popular topic in the research of iodine adsorption materials. Herein, we report an electron-rich porous organic polymer (PTZ-TPC-MA), obtained by Schiff base polycondensation reaction between melamine(MA) and aldehyde monomer with high yield and simplicity. It structures was characterized through FT-IR, 13C CP/MAS NMR and other material analysis measurements. The PTZ-TPC-MA material, being abundant in N and S heteroatoms, the adsorption capacity for iodine vapor, reaching up to 198.1 wt%,and it demonstrates removal rate of 79.8% for iodine from hexane solution. In addition, the recyclability tests have also confirmed its excellent reusability. The material showed better iodine capture capacity for gaseous iodine and iodine in solution. Thus PTZ-TPC-MA material thus emerges as an optimal absorber for iodine capture, offering an effective strategy to solve environmental problems.

Enhancing Output Signals of Sport Monitors Based on Triboelectric Porous PVDF Nanogenerators via Concaving Cells and Cell-Packing Structures.

Porous triboelectric polymer materials are widely used in portable sensors due to their lightweight and suitable mechanical performance, but their triboelectric properties need to be improved. Here, we propose a two-step strategy to concave the cell and cell-packing structure of triboelectric materials based on porous poly(vinylidene fluoride) (PVDF). The first step is to prepare triboelectric nanogenerators (TENGs) of PVDF with a concave cell-packing structure via oriented phase inversion. The second step is to concave the cells by radial and axial compression. The results reveal that the concavities in the cell structure at the radial direction and in the cell-packing structure at the axial direction improve the output signals of the porous PVDF TENG by ca. 150 and 110%, respectively. By contrast, the concaving in cell structure at the radial direction exerts a positive effect on triboelectric performance only when the radial compression strain is not bigger than 17.5%, especially when the cell wall is thin (ca. 0.85 μm). Meanwhile, the concavity-based strategy eliminates the irreversible deformation behavior of the porous PVDF material, enhancing its elasticity. The stability test shows that the sensor based on those materials is stable under 12,500 cycles, and the variance in the square derivation of output voltage is less than 1% during the cycle friction. Such stable and triboelectric-improved materials are assembled into sports-monitoring devices, providing an idea for the application of TENG in smart sensing.

Computational aspects of entropy measures for metal organic frameworks

ABSTRACT A form of porous polymeric material known as metal-organic frameworks is made up of metal ions connected by organic bridging ligands. Entropy is used as a complexity indicator for graphs and is regarded as the graph's structural information content. The graph entropies have evolved into information-theoretic variables for computing the structure information of chemical graphs. The potential use in chemistry of the graph entropy portion has gained the attention of the research community. In this article, we investigate the explicit expressions of graph entropies for two categories of metal organic frameworks (MOFs) named as, M 1 TPyP − M 2 (TPyP= 5, 10, 15, 20-tetrakis (4-pyridyl) porphyrin and M 1 , M 2 = Fe and Co) MOFs and butylated hydroxytoluene-(BHT-) based metal-organic (M= Co, Fe, Mn, Cr) (MBHT) frameworks. we compute some numeric values for certain graph entropies in Tables. In the last, we present a comprehensive graphic comparison of our new results.