Thermally Induced Phase Separation Research Articles

Synthetic Periodontal Guided Tissue Regeneration Membrane with Self-Assembling Biphasic Structure and Temperature-Sensitive Shape Maintenance.

Periodontal disease poses significant challenges to the long-term stability of oral health by destroying the supporting structures of teeth. Guided tissue regeneration techniques, particularly barrier membranes, enable local regeneration by providing an isolated, protected compartment for osseous wound healing while excluding epithelial tissue. Here, this study reports on a thermosensitive periodontal membrane (TSPM) technology designed to overcome the mechanical limitations of current membranes through a semi-interpenetrating network of high molecular weight poly(L-lactic acid) (PLLA) and in situ-polymerized mesh of poly(ε-caprolactone)diacrylate (PCL-DA), and poly lactide-co-glycolide diacrylate (PLGA-DA). An optimized composition allows facile reshaping at greater than 52 °C and rigid shape maintenance at physiological temperature. Its unique bilayer morphology is achieved through self-assembly and thermally-induced phase separation, resulting in distinct yet continuous smooth and nanofibrous compartments adequate for epithelial occlusion and regeneration. Incorporating PLGA-DA enhances the membrane's hydrophilicity and degradation properties, facilitating a more rapid and controlled degradation and therapeutic delivery. This study demonstrates its ability to promote local regeneration by serving as a barrier membrane and simultaneously as a scaffolding matrix in a rat orthotopic periodontal defect model. The TSPM outperformed a clinically available material (Epi-Guide) to facilitate robust alveolar bone and periodontal ligament regeneration at 4 and 8 weeks.

Bioinspired Hydrophobicity via Temperature-Induced Phase Separation of Beeswax: A Pathway for Developing Cellulose Nanofiber-Based Adsorbents for the Removal of Conventional Tetracycline Tablets.

Cellulose nanofiber-based aerogels (CNFAs) hold immense promise across diverse fields, but their innate hydrophilicity and structural fragility in water have constrained their utility in water purification. This study introduces a green approach to induce hydrophobicity into CNFAs via thermally induced phase separation (TIPS) of beeswax, which was adhered to the nanofiber by hydrogen bonding and hydrophobic-hydrophobic interactions. The fabricated aerogel was characterized by using FTIR, SEM, XRD, TGA, contact angle, BET, and compression test. The resulting beeswax cellulose nanofiber-based aerogels (BCNFAs) possess a highly porous structure and extremely low density, enabling the aerogels to self-float and facilitate practical applications and recycling. Due to these remarkable characteristics, BCNFAs had excellent adsorption capacity within 10 min to effectively remove tetracycline (TC) from water with an adsorption capacity of 31.6 mg/g. The demonstrated methodology to induce hydrophobicity in CNFAs via TIPS of beeswax on CNFAs could be an eco-friendly and scalable approach for the fabrication of robust BCNFAs without using any toxic chemicals. So far, this is the first report on to make robust hydrophobic CNFAs by employing TIPS of beeswax while maintaining the porosity of CNFAs, which is highly desirable for effective TC tablet adsorption from water in the present context. The demonstrated work has commercial potential as it focuses on the practical utility of the modified aerogel for adsorbing conventional tetracycline tablets, rather than exclusively targeting the pharmaceutical ingredient alone.

Impact of polymer molecular weight and dispersity on the coalescence of polypropylene powders suitable for laser powder bed fusion

Understanding and controlling the fundamental processes governing the coalescence of polymers is vital to enable the design of polymeric materials for improved mechanical performance and quality of manufactured structures, including those fabricated via additive manufacturing techniques. Our group has utilized thermally induced phase separation (TIPS) to produce spherical and size controlled polypropylene (PP) powders from 12,000 (12k), 250,000 (250k), and 340,000 (340k) molecular weight (Mw) PP, including 50-50 wt% blends of 12k/250k,12k/340k, and 250k/340k, and a 33-33-33 wt% blend of 12k/250k/340k to investigate the impact of polymer Mw, and thus zero-shear viscosity, on particle coalescence and its implication in laser powder bed fusion. The particles exhibit similar size distributions with an average particle size, Dx(50), in the range of 58 μm–86 μm. The coalescence behavior of the powders, evaluated via hot-stage microscopy, show that adding 12k PP in the blend significantly alters the coalescence dynamics of the 250k and 340k PP, dramatically increasing their coalescence rate. The substantial drop in zero-shear viscosity with addition of 12k PP provides the driving force for the pronounced enhancement in coalescence. Strong agreement between experimental results and the Hopper model of coalescence is observed only if corrected for extensional flow, exemplifying the importance of extensional flow on the coalescence process. The results also indicate that the 12k PP in the blend does not surface segregate in the TIPS process, but is homogeneously distributed in the blend. More broadly, these results provide molecular-level insight into how control of powder molecular weight characteristics and viscosity can offer pathways to optimize the consolidation of particles in manufacturing processes, including laser powder bed fusion.

Preparation of nanoporous poly (L-lactic acid) microspheres with controllable morphology via thermally-induced phase separation

This article describes a facile method to prepare nanoporous poly (l-lactic acid) microspheres via a thermally-induced phase separation method with controllable diameters. It was found that the morphology and diameter of PLLA microspheres were easily controlled by adjusting solvent ratio, quenching temperature, and PLLA concentrations. The results revealed that by using a ternary solvent system consisting of 1,3-dioxolane as a good solvent, 2-butanone as mid-solvent, and water as a poor solvent, the diameter of PLLA microspheres can be easily controlled by changing the ratio of 1,3-dioxolane and water. The diameter of PLLA microspheres prepared ranged from 28.8 ± 5.9 μm to 63.8 ± 12.5 μm. Moreover, the evolution of PLLA spherulitic structures grown from polymer solution was confirmed as well through varying solvent ratios and PLLA concentrations. The presence of water as a non-solvent governed the phase separation mechanism of the phase separation process. At the same time, the diameter of the spherulites is affected by the ratio of 1,3-dioxolane controlling the polymer crystallization process in the polymer-rich region. Interestingly, the surface of these spherulites contains nanopores due to the stacking of lamellar crystals of PLLA during polymer crystallization which contributed to its superhydrophobicity and superoleophilicity. Hence, the prepared PLLA spherulites were utilized as PLLA microspheres with nanoporous surfaces for the adsorption and removal of oil in oil/water and oil-in-water emulsion. This facile method provides a novel pathway to prepare nanoporous PLLA microspheres with controllable diameters for eco-friendly oil/water and oil-in-water separation applications.

Construction of zwitterionic surface of PVDF hollow fiber membrane and the study on the mechanism of “autonomy-response” synergistic enhancement anti-fouling

In this study, polyvinylidene fluoride (PVDF)/styryl maleic anhydride (SMA) hollow fiber membrane was fabricated using the Thermally Induced Phase Separation (TIPS) technique. Subsequently, zwitterion-sulfobetaine methacrylate (SBMA) was introduced to the membrane surface through a Michael addition reaction to create a nearly electrically neutral membrane surface. This modification effectively mitigated the high adsorption of differently charged protein pollutants on the membrane surface, thereby enhancing its anti-fouling performance. Simultaneously, the membrane surfaces with positive and negative charges were separately constructed, and the impact of membrane surface charge properties on the anti-fouling performance against positively and negatively charged foulants was investigated. Furthermore, detailed studies were conducted on the chemical structure, surface morphology, performance, and anti-fouling mechanism of the modified membranes. The results indicate that the electrically neutral membrane modified by zwitterionic SBMA exhibited excellent anti-fouling properties against both bovine serum albumin (BSA) and lysozyme (LYZ), with a flux recovery rate (FRR) reaching 96.5 % and 94.6 %, respectively. The static adsorption capacities of BSA and LYZ on the membrane surface decreased to 5.89 μg cm−2 and 9.53 μg cm−2, respectively. Furthermore, the study investigated the structure of the hydration layer formed by zwitterionic SBMA on the membrane surface, as well as its hydration capacity and anti-fouling mechanism. Subsequently, through an assessment of the long-term stability of the modified membrane and its flux recovery rate (FRR), in conjunction with theories related to hydration layers and thermodynamics, it elucidated the anti-fouling mechanism involving “autonomy-response” synergistic enhancement of zwitterions. These findings will offer new strategies for researching hollow fiber membranes with superior anti-fouling properties and for applying zwitterions in membrane technology.

Electrochemical Characterization of Non-Aqueous and Aqueous Gel Polymer Electrolytes for Zinc-Ion Fiber Batteries

The increasing miniaturization of integrated circuits has enabled a wide variety of new applications for embedded sensors and smart devices. Miniaturization of their power sources, however, has lagged in comparison. There are many challenges to devising a space-conscious battery, including the power density, mechanical stability, and chemical safety. Batteries made in fiber formats are of interest for use in wearable electronics. Recent studies have shown the feasibility of Li-ion battery chemistries in drawn polymer fibers via thermally induced phase separation (TIPS)1,2 but key performance gaps in safety and reliability of these fiber batteries remain.In addition to Li-ion, zinc-manganese dioxide (Zn-MnO2) chemistries are particularly good candidates for fiber format batteries due to their relatively low raw material cost, low reactivity, and tolerance of environmental contaminants such as water. Our work has focused on two Zn-MnO2 gel polymer electrolyte (GPE) cell formats: one non-aqueous polyvinylidene fluoride (PVDF) based gel polymer electrolyte, the other an aqueous polyvinyl alcohol (PVA) based GPE. In this work, we synthesize, characterize, and compare these two electrolyte formats head-to-head in both Zn-Zn symmetric cells and Zn-MnO2 full cells.After the GPEs were synthesized, thermo-gravimetric analysis was used to characterize the gels and evaluate the feasibility of drawing the GPE of interest into fibers. We synthesized zinc salt containing PVDF-based GPEs and characterized them in ionic blocking cells via electrochemical impedance spectroscopy (EIS), achieving conductivities of 1.8 mS/cm2. We also assembled Zn-Zn symmetric cells, investigated key performance characteristics such as the transport number and the electrochemical stability window, and stably cycled them for over 500 hours at 0.5 mA/cm2. Lastly, we assembled Zn-MnO2 full cells to confirm the battery performance.

Poly(4-methyl-1-pentene)/ polypropylene alloy hollow fiber membrane with high rigidity for blood oxygenation

The oxygenator with hollow fiber membranes (HFMs) is the key component of the extracorporeal membrane oxygenation which allows the blood to be oxygenated and the carbon dioxide to be removed. The poly(4-methyl-1-pentene) (PMP) is recognized as the optimal oxygenated membrane material with high gas permeability coefficient, and the oxygenated membrane fabricated from it has an asymmetric structure that can resist plasma leakage for a long period of time. However, the relatively low rigidity of PMP oxygenated membrane makes it difficult to be processed in subsequent weaving and applications, during which deformation and fracture of HFMs often happen. In this work, the polymer alloy oxygenated membranes are fabricated by blending polypropylene (PP) as a high rigidity reinforcement agent with PMP via thermally induced phase separation (TIPS). Firstly, the effect of the PP content on phase separation structure and crystallization of alloy flat sheet membrane are investigated. When the PP content is 15 wt%, the rigidity of the alloy membrane reinforces dramatically. The elastic modulus and tensile strength of the PMP-PP-15 alloy membrane is 288.5 ± 12.4 MPa and 8.3 ± 0.4 MPa, respectively, which is 275.7 % and 96.7 % higher than that of the PMP membrane. Furthermore, PMP-PP-15 alloy HFM are fabricated under the optimum polymer composition. The elastic modulus of the PMP-PP-15 alloy HFM is 312.6 ± 16.0 MPa, which is 679.6 % higher than that of the PMP HFM and 40.1 % higher than that of the commercial PMP HFM. Meanwhile, the tensile strength and fracture stress are 15.4 ± 0.7 MPa and 186 ± 12.2 cN, respectively, which are both higher than those of the PMP and commercial PMP HFM. In addition, the PMP-PP-15 alloy HFM shows high gas permeability and oxygenation performance. This study might provide a convenient method to achieve rigidity reinforcement of PMP-based oxygenated membranes with great potential for application.

Fabrication and Solidification Kinetics of Thin Polyethylene Films via Thermally-Induced Phase Separation (TIPS) with Well-Controlled Thickness

Fabrication and Solidification Kinetics of Thin Polyethylene Films via Thermally-Induced Phase Separation (TIPS) with Well-Controlled Thickness

Fabrication Strategies for Bioceramic Scaffolds in Bone Tissue Engineering with Generative Design Applications.

The aim of this study is to provide an overview of the current state-of-the-art in the fabrication of bioceramic scaffolds for bone tissue engineering, with an emphasis on the use of three-dimensional (3D) technologies coupled with generative design principles. The field of modern medicine has witnessed remarkable advancements and continuous innovation in recent decades, driven by a relentless desire to improve patient outcomes and quality of life. Central to this progress is the field of tissue engineering, which holds immense promise for regenerative medicine applications. Scaffolds are integral to tissue engineering and serve as 3D frameworks that support cell attachment, proliferation, and differentiation. A wide array of materials has been explored for the fabrication of scaffolds, including bioceramics (i.e., hydroxyapatite, beta-tricalcium phosphate, bioglasses) and bioceramic-polymer composites, each offering unique properties and functionalities tailored to specific applications. Several fabrication methods, such as thermal-induced phase separation, electrospinning, freeze-drying, gas foaming, particle leaching/solvent casting, fused deposition modeling, 3D printing, stereolithography and selective laser sintering, will be introduced and thoroughly analyzed and discussed from the point of view of their unique characteristics, which have proven invaluable for obtaining bioceramic scaffolds. Moreover, by highlighting the important role of generative design in scaffold optimization, this review seeks to pave the way for the development of innovative strategies and personalized solutions to address significant gaps in the current literature, mainly related to complex bone defects in bone tissue engineering.

Injectable biodegradable microcarriers for iPSC expansion and cardiomyocyte differentiation.

Cell therapy is a potential novel treatment for cardiac regeneration and numerous studies have attempted to transplant cells to regenerate the myocardium lost during myocardial infarction. To date, only minimal improvements to cardiac function have been reported. This is likely to be the result of low cell retention and survival following transplantation. This study aimed to improve the delivery and engraftment of viable cells by using an injectable microcarrier that provides an implantable, biodegradable substrate for attachment and growth of cardiomyocytes derived from induced pluripotent stem cells (iPSC). We describe the fabrication and characterisation of Thermally Induced Phase Separation (TIPS) microcarriers and their surface modification to enable iPSC-derived cardiomyocyte attachment in xeno-free conditions is described. The selected formulation resulted in iPSC attachment, expansion, and retention of pluripotent phenotype. Differentiation of iPSC into cardiomyocytes on the microcarriers is investigated in comparison with culture on 2D tissue culture plastic surfaces. Microcarrier culture is shown to support culture of a mature cardiomyocyte phenotype, be compatible with injectable delivery, and reduce anoikis. The findings from this study demonstrate that TIPS microcarriers provide a supporting matrix for culturing iPSC and iPSC-derived cardiomyocytes in vitro and are suitable as an injectable cell-substrate for cardiac regeneration.

Poly-l-Lactic Acid Scaffolds Additivated with Rosmarinic Acid: A Multi-Analytical Approach to Assess The Morphology, Thermal Behavior, and Hydrophilicity.

This study aims to demonstrate the possibility of incorporating a natural antioxidant biomolecule into polymeric porous scaffolds. To this end, Poly-l-Lactic Acid (PLLA) scaffolds were produced using the Thermally Induced Phase Separation (TIPS) technique and additivated with different amounts of rosmarinic acid (RA). The scaffolds, with a diameter of 4 mm and a thickness of 2 mm, were characterized with a multi-analytical approach. Specifically, Scanning Electron Microscopy analyses demonstrated the presence of an interconnected porous network, characterized by a layer of RA at the level of the pore's surfaces. Moreover, the presence of RA biomolecules increased the hydrophilic nature of the sample, as evidenced by the decrease in the contact angle with water from 128° to 76°. The structure of PLLA and PLLA containing RA molecules has been investigated through DSC and XRD analyses, and the obtained results suggest that the crystallinity decreases when increasing the RA content. This approach is cost-effective, and it can be customized with different biomolecules, offering the possibility of producing porous polymeric structures containing antioxidant molecules. These scaffolds meet the requirements of tissue engineering and could offer a potential solution to reduce inflammation associated with scaffold implantation, thus improving tissue regeneration.

Additive manufacturing of porous ceramic structures by indirect powder bed fusion with laser beam using a novel polyamide/alumina-based feedstock

Porous alumina structures were developed by indirect Powder Bed Fusion with Laser Beam (PBF-LB), employing a novel feedstock (composite granules) based on alumina (Al2O3), bio-renewable polyamide 612 (PA612), and micron-sized graphite (MG) using a commercial PBF-LB machine that operates with a low-power visible light diode laser. Regular and slightly rounded composite granules were prepared via the thermally induced phase separation (TIPS) process in dimethyl sulfoxide (DMSO) using 0.05 vol% of PA612, 40/60 vol% of Al2O3/PA612 and 6.25 wt% of MG, and then characterized via density measurements, Hausner's ratio, SEM-EDS, particle size distribution, Raman spectroscopy, DSC, and TGA. Experimental conditions to be used in the PBF-LB process were determined in order to obtain high-quality green porous structures with a controlled geometry. After the heating treatments, sintered components with good structural integrity, a high open porosity associated with interconnected pores in the struts, and a ceramic matrix with microsized-equiaxial grains were obtained. The evaluation of the mechanical properties was performed by diametral compression testing. In order to improve these properties, a vacuum infiltration process involving a low-concentration alumina-ethanol suspension was used on pre-sintered discs. As a consequence of the infiltration process, the discs showed improved mechanical properties after sintering without the porosity having been significantly affected.

Tuning pore size and density of rigid polylactic acid foams through thermally induced phase separation and optimization using response surface methodology

Rigid polylactic acid (PLA) foams fabricated via thermally induced phase separation (TIPS) utilizing a ternary solution of PLA, Tetrahydrofuran (THF), and water. The PLA gels were stabilized mechanically by the substituting of the THF/water solvent mixture with ethanol as non-solvent and subsequently vacuum dried. A comprehensive characterization of PLA foams was achieved by Scanning Electron Microscopy (SEM), X-ray Diffractometry (XRD) and Brunauer–Emmett–Teller (BET) analyses. The BET area obtained in the PLA foam is up to 18.76 m2/g. The Response Surface Methodology (RSM) was utilized to assess the impacts of four independent variables (polymer concentration, solvent composition, quench temperature, and aging time) on the pore size and density of PLA foam. The experimental findings demonstrated that the fabrication parameters could be fine-tuned to govern the morphology of the pores, comprising their size and density. The optimal values of parameters for cell size were identified by RSM to be 8.96 (wt%), 91.60 (w/w), 5.50 °C, and 3.86 h for the optimum cell size of 37.96 µm (37.78 by Genetic Algorithm). Optimum density by RSM 88.88 mgr/cm3 (88.38 mgr/cm3 by Genetic Algorithm) was obtained at 5.00 (wt%), 89.33 (w/w), 14.40 °C and 2.65 h.

Formation of Microporous Poly Acrylonitrile-Co-Methyl Acrylate Membrane via Thermally Induced Phase Separation for Immiscible Oil/Water Separation.

An interconnected sponge structure and porous surface poly (acrylonitrile-co-methyl acrylate) (P(AN-MA)) microfiltration membranes (MF) were fabricated via thermally induced phase separation (TIPS) by using caprolactam (CPL), and acetamide (AC) as the mixed diluent. When the ternary system was composed of 15 wt.% P(AN-MA), 90 wt.% CPL, and 10 wt.% AC and formed in a 25 °C air bath, the membrane exhibited the highest water flux of 8107 L/m2·h. The P(AN-MA) membrane contained hydrophobic groups (-COOCH3) and hydrophilic groups (-CN), leading it to exhibit oleophobic properties underwater and hydrophobic properties in oil. The membrane demonstrates efficient separation of immiscible oil/water mixtures. The pure water flux of the petroleum ether/water mixture measured 870 L/m2·h, and the pure oil flux of the petroleum tetrachloride/water mixture measured 1230 L/m2·h under the influence of gravity. Additionally, the recovery efficiency of diluents through recrystallization was 85.3%, significantly reducing potential pollution and production costs.

Diffusion mediated thermally induced phase separation for preparing poly(vinylidene fluoride) membranes with enhanced separation performances

Thermally induced phase separation (TIPS) process is an appealing method for preparing poly(vinylidene fluoride) (PVDF) membranes for separation. In this work, we developed a diffusion mediated thermally induced phase separation (d-TIPS) to prepare PVDF membranes with great molecules separation performances. We investigated the thermodynamics of ternary polymer solutions including PVDF, caprolactam (CPL), and Polyethylene glycol (PEG). We controlled liquid–liquid phase separation and the CPL diffusion by adjusting the addition of PEG and molecular weight to modulate the evolution of morphology from spherulitic to bicontinuous structure. The resulting membrane was characterized by morphology, surface chemistry, tensile strength, water contact angle, and perm-selectivity. The membrane was further stretched for enhanced strength, permeance, and rejection. This work provides a fundamental understanding of the diffusion mediated thermally induced phase separation and shows the great potential of PVDF membranes in macromolecules separation.

SC crystals of porous PLA via thermally–induced phase separation: Effects of process conditions, solvent composition and nucleating agent

The formation of stereo-complex crystals (SC) in porous poly (lactic acid) (PLA) material is intricately linked with improving its comprehensive properties. In this work, the effects of process conditions, solvent composition and additional nucleating agent on SC crystals during the fabrication of porous PLA through thermally-induced phase separation method were studied. Crystallization behavior of SC crystals during the pore-forming process is systematically investigated, revealing that higher quenching temperature and longer quenching period facilitate the formation of SC crystals. Additionally, the addition of deionized water to the solvent effectively enhances SC crystals formation by reducing solution viscosity and prolonging the phase separation time. The highest crystallinity of SC crystals (XSC) can be achieved, reaching 30.6%, when the water content is controlled at 1.6%. Furthermore, the introduction of carbon nanotubes (CNTs) as a nucleating agent exhibits a pronounced effect on the formation of SC crystals. When incorporating a 3 wt% content of CNTs, XSC reaches its peak value at 37.7%. This work is helpful to provide reference for improving mechanical properties and heat resistance of porous PLA, thereby expanding its potential outdoor applications.

Thermally Induced Phase Separation of the PEDOT:PSS Layer for Highly Efficient Laminated Polymer Light-Emitting Diodes.

Among various conductive polymers, the poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) film has been studied as a promising material for use as a transparent electrode and a hole-injecting layer in organic optoelectronic devices. Due to the increasing demand for the low-cost fabrication of organic light-emitting diodes (OLEDs), PEDOT:PSS has been employed as the top electrode by using the coating or lamination method. Herein, a facile method is reported for the fabrication of highly efficient polymer light-emitting diodes (PLEDs) based on a laminated transparent electrode (LTE) consisting of successive PEDOT:PSS and silver-nanowire (AgNW) layers. In particular, thermally induced phase separation (TIPS) of the PEDOT:PSS film is found to depend on the annealing temperature (Tanneal) during preparation of the LTE. At Tanneal close to the glass transition temperature of the PSS chains, a PSS-rich phase with a large number of PSS- molecules enhances the work function of the PEDOT:PSS on the glass-side surface relative to the air side. By using the optimized LTEs, bidirectional laminated PLEDs are obtained with a total external quantum efficiency of 2.9% and a turn-on voltage of 2.6 V, giving a comparable performance to that of the reference bottom-emitting PLED based on a costly evaporated metal electrode. In addition, an analysis of the angular characteristics, including the variation in the electroluminescence spectra and the change in luminance according to the emission angle, indicates that the laminated PLED with the LTE provides a more uniform angular distribution regardless of the direction of emission. Detailed optical and electrical analyses are also performed to evaluate the suitability of LTEs for the low-cost fabrication of efficient PLEDs.

A hierarchically cellulose porous monolith doped with CNTs/Al2O3 fibers, exhibiting super-hydrophilicity and underwater superoleophobicity for efficient solar-driven desalination

The utilization of solar-driven interfacial desalination is widely regarded as a promising technological approach for mitigating the global water crisis. Existing solar interface evaporators often face limitations such as salt accumulation and oil waste liquid interference, impeding water supply channels and the efficient escape of interface water vapor, consequently diminishing the evaporation rate. This study proposes a novel approach by synthesizing a monolithic structure composed of carbon nanotubes (CNTs) and vertically arranged Al2O3 fibers which are embedded in cellulose skeleton, achieved through the thermally induced phase separation (TIPS) method. The resulting hierarchically porous monolith exhibits high steam generation rate, remarkable superhydrophilic properties and underwater superoleophobicity, rendering it highly effective in salt tolerance and resistance against oil pollution. In particular, highly oriented Al2O3 fibers form multiple thermal localization arrays and steam dissipation channels，complemented by interconnected hydrophilic skeleton that achieved strong synergy, enabling a stable and high evaporation rate of 1.98 kg m−2 h−1 and 2.06 kg m−2 h−1 in high salt concentration (10 wt%) seawater and oil-in-water (O/W) emulsion, respectively. This work contributes to the ongoing efforts in advancing next-generation solar vapor generators, aiming to enhance the sustainability and efficiency of freshwater production in response to the global water crisis.

Fabrication of hydrophilic PVDF ultrafiltration membranes via thermally induced phase separation coupled with amphiphilic copolymer deposition

In this work, we propose a facile one-step method to fabricate poly(vinylidene fluoride) (PVDF) ultrafiltration hollow fiber membranes through coupled thermally induced phase separation (TIPS) and deposition of amphiphilic copolymer poly(styrene-co-maleic anhydride) (PSMA). A thorough examination of how the addition of PSMA influenced the membrane formation and performance was conducted. The mechanism behind the synergistic effect between TIPS process and deposition of PSMA on the membrane surface was discussed in detail. The difference in the phase separation behavior of PVDF and PSMA during membrane preparation caused the deposition of PSMA forming a hydrophilic layer on the PVDF porous structure without altering the membrane bulk structure. The enrichment of PSMA in membrane outer surface not only improved the hydrophilicity of the membrane, but also effectively reduced the membrane pore size, while maintaining the overall bulk porosity. PSMA deposition resulted in enhanced pure water flux and BSA rejection, effectively overcoming the traditional trade-off between permeability and selectivity. This straightforward approach of blending suitable amphiphilic copolymers into the polymer solution exhibited significant potential for the rapid and large-scale preparation of hydrophilic PVDF-based ultrafiltration membranes in the TIPS process.

Influence of the solvent removal method on the morphology of polystyrene porous structures prepared via thermally induced phase separation

Thermally induced phase separation (TIPS) allows preparation of nano and micro-porous structured materials for various applications. The literature thoroughly examines the impact of initial polymer solution concentration and cooling rate on the products morphology. On the contrary, the influence of the solvent removal methods was so far researched scarcely. Hence, we compare both qualitatively and quantitatively the effects of the solvent removal method on pore size distribution, structure, porosity, and thermal conductivity. Our study was carried out with samples prepared by TIPS from polystyrene/cyclohexane solutions employing either extraction agent or lyophilization at different solvent removal temperatures. Materials exhibited interconnected pore structure, implying good sound insulation properties, and had low thermal conductivity, offering the combination of thermal and sound insulation in one layer of material. Pore sizes after lyophilization were up to two times larger than after solvent removal by an extraction agent. On the other hand, the use of extraction agent led up to 10% porosity decrease with average porosity after lyophilization being above 82%. Our findings demonstrate that the solvent removal method is an important parameter during TIPS and that pros and cons of both methods should be carefully considered to obtain optimal material and TIPS process economy.