Search

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Polypropylene-based aerogels with high surface area have been developed for the first time. By chemical crosslinking of polypropylene with oligomeric capped-end amino compounds, followed by dissolution, thermally induced phase separation, and the supercritical CO2 drying process or freeze-drying method, the aerogels exhibit high specific surface areas up to 200 m2/g. Moreover, the silica-cage multi-amino compound was utilized in a similar vein for forming hybrid polypropylene aerogels. According to the SEM, the developed polypropylene-based aerogels exhibit highly porous morphology with micro-nanoscale structural features that can be controlled by processing conditions. Our simple and inexpensive synthetic strategy results in a low-cost, chemically resistant, and highly porous material that can be tailored according to end-use applications. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The escalating prevalence of anterior cruciate ligament (ACL) injuries in sports necessitates innovative strategies for ACL reconstruction. In this study, we propose a multiphasic bone-ligament-bone (BLB) integrated scaffold as a potential solution. The BLB scaffold comprised two polylactic acid (PLA)/deferoxamine (DFO)@mesoporous hydroxyapatite (MHA) thermally induced phase separation (TIPS) scaffolds bridged by silk fibroin (SF)/connective tissue growth factor (CTGF)@Poly(l-lactide-co-ε-caprolactone) (PLCL) nanofiber yarn braided scaffold. This combination mimics the native architecture of the ACL tissue. The mechanical properties of the BLB scaffolds were determined to be compatible with the human ACL. In vitro experiments demonstrated that CTGF induced the expression of ligament-related genes, while TIPS scaffolds loaded with MHA and DFO enhanced the osteogenic-related gene expression of bone marrow stem cells (BMSCs) and promoted the migration and tubular formation of human umbilical vein endothelial cells (HUVECs). In rabbit models, the BLB scaffold efficiently facilitated ligamentization and graft-bone integration processes by providing bioactive substances. The double delivery of DFO and calcium ions by the BLB scaffold synergistically promoted bone regeneration, while CTGF improved collagen formation and ligament healing. Collectively, the findings indicate that the BLB scaffold exhibits substantial promise for ACL reconstruction. Additional investigation and advancement of this scaffold may yield enhanced results in the management of ACL injuries.

In this study, a composite membrane was prepared from recycled low-density polyethylene (R-LDPE), thus helping to lighten plastics' load on the environment, while the powder of alumina was used to enhance the membrane contact angle, its porosity, and its mechanical properties. The membrane preparation was made by means of the thermally induced phase separation method by using the butyl acetate as a solvent, hexane as a non-solvent, and the alumina as an additive. The membrane crystalline property was assessed via the Fourier-transform infrared spectroscopy. The membrane characteristics were then investigated in terms of thickness, contact angle, pore size, porosity, mechanical test, bubble point pressure, atomic force microscopy, and scanning electron microscopy analysis. The results revealed that the addition of alumina had an important role in improving membrane structure, properties and therefore its performance. The evaluation of the R-LDPE-alumina membrane showed that it has a good porosity, good hydrophobicity, and better mechanical properties. The obtained membranes were also applicated to the vacuum membrane distillation to test their performance. [ABSTRACT FROM AUTHOR]

The physical properties of a polymer solution that are composition- and/or temperature-dependent are among the most influential parameters to impact the dynamics and thermodynamics of the phase separation process and, as a result, the morphology formation. In this study, the impact of composition- and temperature-dependent density, heat capacity, and heat conductivity on the membrane structure formation during the thermally induced phase separation process of a high-viscosity polymer solution was investigated via coupling the Cahn–Hilliard equation for phase separation with the Fourier heat transfer equation. The variations of each physical property were also investigated in terms of different boundary conditions and initial solvent volume fractions. It was determined that the physical properties of the polymer solution have a noteworthy impact on the membrane morphology in terms of shorter phase separation time and droplet size. In addition, the influence of enthalpy of demixing in this case is critical because each physical property showed a nonhomogeneous pattern owing to the heat generation during phase separation, which in turn influenced the membrane morphology. Accordingly, it was determined that investigating spinodal decomposition without including heat transfer and the impact of physical properties on the morphology formation would lead to an inadequate understanding of the process, specifically in high-viscosity polymer solutions. [ABSTRACT FROM AUTHOR]

Poly(ether ketone ketone) (PEKK) is a semicrystalline high‐performance polymer with exceptional mechanical properties, high continuous operation temperature, and is insoluble in most common solvents. Porous PEKK, desired for biomedical applications, is produced by a high‐temperature thermally induced phase separation process using PEKK solutions in two high boiling aprotic solvents, 4‐phenylphenol and 9‐fluorenone, with concentrations up to 20 wt.%. It is demonstrated that the solvent choice has a pronounced influence on the phase separation behavior, which determines the foam morphology, physical and mechanical properties of PEKK foams. Porous PEKK with porosities ranging from 70% to 90%, specific surface areas up to 194 m2 g−1 and elastic moduli ranging from 35 to 100 MPa are produced. [ABSTRACT FROM AUTHOR]

Constructing and maintaining a three-dimensional network structure with high porosity is critical to the preparation of silica aerogel materials because this structure provides excellent properties. However, due to the pearl-necklace-like structure and narrow interparticle necks, aerogels have poor mechanical strength and a brittle nature. Developing and designing lightweight silica aerogels with distinct mechanical properties is significant to extend their practical applications. In this work, thermally induced phase separation (TIPS) of poly(methyl methacrylate) (PMMA) from a mixture of ethanol and water was used to strengthen the skeletal network of aerogels. Strong and lightweight PMMA-modified silica aerogels were synthesized via the TIPS method and supercritically dried with carbon dioxide. The cloud point temperature of PMMA solutions, physical characteristics, morphological properties, microstructure, thermal conductivities, and mechanical properties were investigated. The resultant composited aerogels not only exhibit a homogenous mesoporous structure but also achieve a significant improvement in mechanical properties. The addition of PMMA increased the flexural strength and compressive strength by as much as 120% and 1400%, respectively, with the greatest amount of PMMA (Mw = 35,000 g/mole), while the density just increased by 28%. Overall, this research suggests that the TIPS method has great efficiency in reinforcing silica aerogels with less sacrifice of low density and large porosity. [ABSTRACT FROM AUTHOR]

Membrane distillation (MD) can treat high-salinity brine. However, the system's efficiency is hindered by obstacles, including salt scaling and temperature polarization. When properly implemented, surface patterns can improve the mass and heat transfer in the boundary layer, which leads to higher MD efficiency. In this work, the performance of direct contact membrane distillation (DCMD) using Sharklet-patterned poly (vinylidene fluoride) (PVDF) membranes is investigated. Both non-patterned and patterned PVDF membranes are prepared by lithographically templated thermally induced phase separation (lt -TIPS) process with optimized conditions. Sharklet patterns on the membranes improve the DCMD performance: up to 17 % higher water flux and 35 % increased brine-side heat transfer coefficient. The scaling resistance of the membranes during DCMD is tested by both saturated CaSO 4 solution and hypersaline NaCl solutions. Patterned PVDF membranes show an average of 30 % higher water flux and up to 45 % lessened flux decline over time compared with non-patterned membranes when treating high-concentration brines. Post-mortem analysis reveals that Sharklet-patterned membranes display less salt-scaling on surfaces with smaller-sized CaSO 4 and NaCl crystals, maintain a relatively cleaner surface, and exhibit better retention of hydrophobicity. [Display omitted] • Sharklet-patterned PVDF membranes were fabricated with patterning fidelity up to 80 %. • The effects of Sharklet patterns on DCMD performances were quantified. • The Sharklet improves flux by 17 % and brine-side heat transfer coefficient by 35 %. • The Sharklet improves membranes' robustness when treating hypersaline feeds. [ABSTRACT FROM AUTHOR]

Spherical polyamide 12 (PA12) powder for selective laser sintering (SLS) was prepared by thermally induced phase separation (TIPS) method. It was authenticated that the mixed solvent can regulate the liquid–liquid phase separation (LLPS) process by changing the ratio of diluent to non-diluent. The polymer droplets mainly coalesced in the solution, and then the crystal nucleus of PA12 was formed in the droplets. Finally, high crystallinity PA12 powder was precipitated. The morphology, particle size distribution, thermal properties, the change of crystal structure, and powder spreading performances of the obtained powder were characterized. The powder had a narrow particle size distribution, an average particle size of 55.2 μm, and a broad sintering window of 29°C. The results exhibited that the powders prepared by TIPS had excellent sintering properties, and TIPS method provided more choices for SLS technology.

[Display omitted] PNIPAM as a stimuli-responsive polymer has generated extreme interests due to its versatile applications. However, there is no research report on whether PNIPAM micro/nano-particles can be extracted from its suspension after phase separation. In the present work, LCST-type phase separation in self-synthesized PNIPAM/water system was investigated in depth by dividing the DLS testing process into four stages. In addition to quenching duration, temperature rise process, quenching temperature and PNIPAM concentration all have a great influence on particle size of the suspension. Meanwhile, the steady-state rheology and dynamic viscoelasticity results show that PNIPAM micro/nano-particles in the suspension are "soft" that can deform. Finally, FE-SEM was used to observe the morphology of dehydrated PNIPAM extracted by sessile droplet evaporation under different conditions. The results indicate that these "soft" particles are easier to fuse together, do not have sufficient mechanical strength to maintain their spherical morphology after dehydration. But the above fusion can be suppressed by adjusting evaporation conditions to acquire smaller PNIPAM particles which have sufficient mechanical properties to keep their basic particle morphology. Further, by changing evaporation pressure to positive or negative pressure, dehydrated PNIPAM micro/nano-particles with excellent uniformity and separation can be obtained. This work will provide guidance for extracting micro/nano-particles from polymer/diluent systems with LCST. [ABSTRACT FROM AUTHOR]

This study aims at characterization of porous poly(ε-caprolactone) (PCL) scaffolds prepared by the methods of thermally induced phase separation (TIPS) and TIPS supported by particulate leaching (PL). Both techniques were combined with freeze-drying. Two PCL grades (with different average molecular weight characterized by MFR 6.1 and 1.2 g/10 min) were employed in the fabrication of scaffolds. Three types of salt (sodium chloride) particles were used in the TIPS-PL preparation of the PCL sample: (i) smaller particles (S) measuring 200–315 μm, (ii) larger particles (B) measuring 500–600 μm, and (iii) mixture of S and B particles (S/B = 1/1 wt/wt). The crystallization behavior of the PCL solutions and the thermal properties of scaffolds were investigated by polarized light microscopy (PLM) and differential scanning calorimetry (DSC), respectively. The structural changes of PCL were studied by attenuated total reflectance infrared spectroscopy (ATR-FTIR). The scaffold structure was visualized by means of scanning electron microscopy (SEM) and X-Ray micro-computed tomography (X-ray micro-CT). Furthermore, the density, porosity, water uptake, contact angle and compressive properties of scaffold were investigated. The molecular weight of PCL had an impact on the crystallization of the PCL solutions and thereby on the crystallinity of scaffolds and the morphology of pore walls formed during TIPS. Sodium chloride grains had an influence on the pore size and overall morphology of foam scaffolds prepared by TIPS-PL. The addition of NaCl decreased significantly the density and compressive properties and increased the porosity and water uptake of scaffolds.

An experimental quasi-equilibrium phase diagram of the polyvinylidene fluoride (PVDF)–camphor mixture is constructed using an original optical method. For the first time, it contains a boundary curve that describes the dependence of camphor solubility in the amorphous regions of PVDF on temperature. It is argued that this diagram cannot be considered a full analogue of the eutectic phase diagrams of two low-molar-mass crystalline substances. The phase diagram is used to interpret the polarized light hot-stage microscopy data on cooling the above mixtures from a homogeneous state to room temperature and scanning electron microscopy data on the morphology of capillary-porous bodies formed upon camphor removal. Based on our calorimetry and X-ray studies, we put in doubt the possibility of incongruent crystalline complex formation between PVDF and camphor previously suggested by Dasgupta et al. (Macromolecules 2005, 38, 5602–5608). We also describe and discuss the high-temperature crystalline structure of racemic camphor, which is not available in the modern literature. [ABSTRACT FROM AUTHOR]

Owing to the fact that heat transfer during the thermally induced phase separation process is limited, a quench rate is inevitably entailed, which leads to the existence of temporal and spatial variations in temperature. Hence, it is of great importance to take into account the nonisothermality during the phase separation process, especially in high viscosity polymer solutions. In this study, the influence of conductive heat transfer on the morphology formation during the thermally induced phase separation process was investigated theoretically in terms of quench depth, boundary conditions, and enthalpy of demixing to elucidate the interaction between temperature and concentration through incorporating the nonlinear Cahn-Hilliard equation and the Fourier heat transfer equation in two dimensions. The Flory-Huggins free energy theory for the thermodynamics of phase separation, slow mode theory, and Rouse law for polymer diffusion without entanglements were taken into account in the model development. The simulation results indicated a strong interaction between heat transfer and phase separation, which impacted the morphology formation significantly. Results confirmed that quench depth had an indispensable impact on phase separation in terms of higher characteristic frequency by increasing the driving force for heat transfer. Applying quench from various boundaries led to a difference in the quench rate due to the high viscosity of the polymer solution. This led to a gradation in pore size and anisotropic morphology formation. The degree and direction of anisotropy depended on quench depth and rate, quench time, heat conduction rate inside the solution, solution viscosity, temperature evolution, and the enthalpy of demixing. It was also verified that the influence of enthalpy of demixing on phase separation could not be neglected as it increased the solution temperature and led to phase separation being accomplished at a higher temperature than the initial quench temperature. [ABSTRACT FROM AUTHOR]

A high-performance polypropylene hollow fiber membrane (PP-HFM) was prepared by using a binary environmentally friendly solvent of polypropylene as the raw material, adopting the thermally induced phase separation (TIPS) method, and adjusting the raw material ratio. The binary diluents were soybean oil (SO) and acetyl tributyl citrate (ATBC). The suitable SO/ATBC ratio of 7/3 was based on the size change of the L-L phase separation region in PP-SO/ATBC thermodynamic phase diagram. Through the characterization and comparison of the basic performance of PP-HFMs, it was found that with the increase of the diluent content in the raw materials, the micropores of outer surface of the PP-HFM became larger, and the cross section showed a sponge-like pore structure. The fluoropolymer, Hyflon ADx, was deposited on the outer surface of the hollow fiber membrane using a physical modification method of solution dipping. After modification, the surface pore size of the Hyflon AD40L modified membranes decreased; the contact angle increased to around 107°; the surface energy decreased to 17 mN·m−1; and the surface roughness decreased to 17 nm. Hyflon AD40L/PP-HFMs also had more water resistance properties from the variation of wetting curve. For biocompatibility of the membrane, the adsorption capacity of the modified PP membrane for albumin decreased from approximately 1.2 mg·cm−2 to 1.0 mg·cm−2, and the adsorption of platelets decreased under fluorescence microscopy. The decrease in blood cells and protein adsorption in the blood prolonged the clotting time. In addition, the hemolysis rate of modified PP membrane was reduced to within the standard of 5%, and the cell survival rate of its precipitate was above 100%, which also indicated the excellent biocompatibility of fluoropolymer modified membrane. The improvement of hydrophobicity and blood compatibility makes Hyflon AD/PP-HFMs have the potential for application in membrane oxygenators.

Polypropylene (PP) is widely used as oxygenation membrane material for extracorporeal membrane oxygenation. However, the microporous pores and poor hemocompatibility of PP oxygenation membrane hamper the efficient applications in blood gas exchange process. This study utilizes fluorinated copolymer poly (ethylene-chlorotrifluoroethylene) (ECTFE) as blending additive to construct PP/ECTFE flat sheet and hollow fiber membranes (HFM) via thermally induced phase separation (TIPS) for blood oxygenation. The PP:ECTFE-3:1 HFMs exhibited high O 2 and CO 2 exchange rates of ∼319.6 ml min−1 m−2 and ∼1532.3 ml min−1 m−2 in blood gas exchange process, respectively. The introduction of fluorinated segments rendered hydrophobic and low-surface-energy membrane surface, as indicated by the water contact angle of ∼119.2° and surface energy of ∼35.1 mN m−1 of PP:ECTFE-3:1 flat sheet membrane, compared with those of ∼96.8° and ∼41.0 mN m−1 for the PP membrane. Consequently, the liquid entry pressure and hemocompatibility were enhanced, affording resistance to plasma leakage for 189 h, which prolonged 30.5 times than 6 h of PP HFM, and was comparable with the level of poly (4-methyl-1-pentene) (PMP) oxygenation membrane. The PP/ECTFE blend oxygenation membranes possess great potential for biomedical application. [Display omitted] • PP/ECTFE flat sheet membranes and hollow fiber membranes were fabricated. • The membranes exhibit prolonged blood oxygenation performance. • Higher liquid entry pressure and improved hemocompatibility were acquired. • The membranes exhibit enhanced gas permeance and long-term stability. [ABSTRACT FROM AUTHOR]

The effect of a N,N-dimethylformamide (DMF)/acetone solvent system (3:7, 4:6, 5:5, 6:4, 7:3) and spinning medium (air and water) on the membrane morphology and the structure-property relationship were investigated. A facile method was optimized to generate a porous, polymer-fiber membrane via the combinative effect of electrospinning and thermally inducing phase separation of the DMF/acetone (4:6) solvent system in a water medium. The attenuated total reflection (ATR) - Fourier transform infrared (FTIR) results showed an increased β-phase compared to the pristine poly(vinylidene fluoride) (PVDF). The XRD and DSC results further confirmed that the co-existing α- and β-phases in the pristine PVDF were converted into a unique β-phase in the electrospun membranes. In addition, the solvent uptake percentage of the DMF/acetone (4:6) solvent system in a water medium (540) is much greater than that in an air medium (320), and over two times better than that of commercial polyethylene (PE) membranes (190). Similarly, the discharge capacity of the PVDF membrane separator prepared with the DMF/acetone (4:6) solvent system in a water medium is higher than that of the air medium. This enhancement of solvent uptake might be due to the interconnected porous morphology present in the water medium.

Hybrid porous scaffolds composed of both natural and synthetic biopolymers have demonstrated significant improvements in the tissue engineering field. This study investigates for the first time the fabrication route and characterization of poly-L-lactic acid scaffolds blended with polyhydroxyalkanoate up to 30 wt%. The hybrid scaffolds were prepared by a thermally induced phase separation method starting from ternary solutions. The microstructure of the hybrid porous structures was analyzed by scanning electron microscopy and related to the blend composition. The porosity and the wettability of the scaffolds were evaluated through gravimetric and water contact angle measurements, respectively. The scaffolds were also characterized in terms of the surface chemical properties via Fourier transform infrared spectroscopy in attenuated total reflectance. The mechanical properties were analyzed through tensile tests, while the crystallinity of the PLLA/PHA scaffolds was investigated by differential scanning calorimetry and X-ray diffraction. [ABSTRACT FROM AUTHOR]

A new method of fabricating porous membranes based on ultra-high molecular weight polyethylene (UHMWPE) by controlled swelling of the dense film was proposed and successfully utilized. The principle of this method is based on the swelling of non-porous UHMWPE film in organic solvent at elevated temperatures, followed by its cooling and further extraction of organic solvent, resulting in the formation of the porous membrane. In this work, we used commercial UHMWPE film (thickness 155 μm) and o-xylene as a solvent. Either homogeneous mixtures of the polymer melt and solvent or thermoreversible gels with crystallites acting as crosslinks of the inter-macromolecular network (swollen semicrystalline polymer) can be obtained at different soaking times. It was shown that the porous structure and filtration performance of the membranes depended on the swelling degree of the polymer, which can be controlled by the time of polymer soaking in organic solvent at elevated temperature (106 °C was found to be the optimal temperature for UHMWPE). In the case of homogeneous mixtures, the resulting membranes possessed both large and small pores. They were characterized by quite high porosity (45–65% vol.), liquid permeance of 46–134 L m−2 h−1 bar−1, a mean flow pore size of 30–75 nm, and a very high crystallinity degree of 86–89% at a decent tensile strength of 3–9 MPa. For these membranes, rejection of blue dextran dye with a molecular weight of 70 kg/mol was 22–76%. In the case of thermoreversible gels, the resulting membranes had only small pores located in the interlamellar spaces. They were characterized by a lower crystallinity degree of 70–74%, a moderate porosity of 12–28%, liquid permeability of up to 12–26 L m−2 h−1 bar−1, a mean flow pore size of up to 12–17 nm, and a higher tensile strength of 11–20 MPa. These membranes demonstrated blue dextran retention of nearly 100%.

The Hansen solubility parameter (HSP) theory, which includes the Hansen dispersion (D), polar (P), and hydrogen (H) components and a derivative ‘solubility parameter distance, Ra’ parameter, was adopted to evaluate the interaction between different polymers and their various diluents, so as to obtain a valuable and feasible criterion for the diluent selection of the thermally induced phase separation (TIPS) process for the preparation of polymeric membranes. Firstly, a full-scale database of the four HSP parameters of typical polymer-diluent systems was obtained based on a complete literature review about the phase separation process of all the polymer/diluents systems that have been applied to prepare polymeric membranes via TIPS and our additional exploratory experiments for membrane formation mechanism, in which two different phase separation processes including solid to liquid and liquid to liquid were distinguished. Relationships between the Ra parameter and the phase separation behavior were figured out to get a criterion for selecting the single diluent for the typical polymers. Moreover, the diluent selection was extended by adding a second diluent, and a schematic three-dimensional phase diagram was drawn to provide a feasible understanding of the TIPS process of the polymer-binary diluent system. Taking polypropylene (PP) as the representative example, plenty of exploratory experiments for the membrane formation mechanism based on a literature review were conducted to propose a guide based on the Hansen polar and hydrogen solubility component parameters to help select a proper binary diluent system.

Objective(s): The present study aimed to prepare polycaprolactone (PCL) scaffolds with high porosity and pore interconnectivity, in order to copy the microstructure of natural bones using the thermally induced phase separation (TIPS) technique. Materials and Methods: The scaffolds were coated with chitosan (CH), bioactive glass (BG), and gelatin nanoparticles (GEL NPs) and assessed using scanning electron microscopy and Fourier-transform infrared spectroscopy (FTIR). Results: The size of the prepared BG and GEL NPs was estimated to be 400 and 234 nanometers, respectively. The porosity and contact angle of PCL/CH/GEL NPs/BG was 74% and 72°, respectively. Weight loss and electron microscopy evaluations indicated the improved degradation rate of the scaffolds and spreading tendency of the cells on the scaffolds when modified as compared to the scaffolds that were purely obtained from PCL. In addition, the in-vitro studies revealed that the MG-63 cells cultured on the PCL/CH/GEL NPs/BG scaffolds showed improved cell proliferation more significantly compared to the scaffolds obtained from PCL, PCL/CH/GEL NPs, PCL/CH, and PCL/GEL NPs. Mechanical examinations also showed that PCL/CH/GEL/BG scaffolds had the highest mechanical strength compared to other groups (i.e., 4.66 Mpa). Cell viability was estimated to be 96.7%, and the alizarin red test indicated the significant improvement of mineralization in the PCL/CH/GEL NP group. Conclusion: According to the results, the PCL scaffolds that were modified by CH/GEL NPs/BG had the high potency to be used as bone tissue engineering scaffolds.

One of the materials that attracts attention as a potential material for membrane formation is ultrahigh molecular weight polyethylene (UHMWPE). One potential material for membrane formation is ultrahigh molecular weight polyethylene (UHMWPE). The present review summarizes the results of studies carried out over the last 30 years in the field of preparation, modification and structure and property control of membranes made from ultrahigh molecular weight polyethylene. The review also presents a classification of the methods of membrane formation from this polymer and analyzes the conventional (based on the analysis of incomplete phase diagrams) and alternative (based on the analysis of phase diagrams supplemented by a boundary line reflecting the polymer swelling degree dependence on temperature) physicochemical concepts of the thermally induced phase separation (TIPS) method used to prepare UHMWPE membranes. It also considers the main ways to control the structure and properties of UHMWPE membranes obtained by TIPS and the original variations of this method. This review discusses the current challenges in UHMWPE membrane formation, such as the preparation of a homogeneous solution and membrane shrinkage. Finally, the article speculates about the modification and application of UHMWPE membranes and further development prospects. Thus, this paper summarizes the achievements in all aspects of UHMWPE membrane studies.

For the first time, we have successfully fabricated microfiltration (MF) hollow fiber membranes by the thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS) methods using cellulose acetate benzoate (CBzOH), which is a cellulose derivative with considerable chemical resistance. To obtain an appropriate CBzOH TIPS membrane, a comprehensive solvent screening was performed to choose the appropriate solvent to obtain a membrane with a porous structure. In parallel, the CBzOH membrane was prepared by the NIPS method to compare and evaluate the effect of membrane structure using the same polymer material. Prepared CBzOH membrane by TIPS method showed high porosity, pore size around 100 nm or larger and high pure water permeability (PWP) with slightly low rection performance compared to that by NIPS. On the contrary, CBzOH membranes prepared with the NIPS method showed three times lower PWP with higher rejection. The chemical resistance of the prepared CBzOH membranes was compared with that of cellulose triacetate (CTA) hollow fiber membrane, which is a typical cellulose derivative as a control membrane, using a 2000 ppm sodium hypochlorite (NaClO) solution. CBzOH membranes prepared with TIPS and NIPS methods showed considerable resistance against the NaClO solution regardless of the membrane structure, porosity and pore size. On the other hand, when the CTA membrane, as the control membrane, was subjected to the NaClO solution, membrane mechanical strength sharply decreased over the exposure time to NaClO. It is interesting that although the CBzOH TIPS membrane showed three times higher pure water permeability than other membranes with slightly lower rejection and considerably higher NaClO resistance, the mechanical strength of this membrane is more than two times higher than other membranes. While CBzOH samples showed no change in chemical structure and contact angle, CTA showed considerable change in chemical structure and a sharp decrease in contact angle after treatment with NaClO. Thus, CBzOH TIPS hollow fiber membrane is noticeably interesting considering membrane performance in terms of filtration performance, mechanical strength and chemical resistance on the cost of slightly losing rejection performance.

Prostate cancer is a leading cause of death in men and despite improved surgical procedures that aid tumor resection, the risk of recurrence after surgery as a result of positive resection margins remains significant. Adjuvant chemotherapy is often required but this is associated with toxicity. Improved ways of delivering highly toxic chemotherapeutic drugs in a more controlled and targeted manner after the prostate has been removed during surgery could reduce the risk of recurrence and avoid systemic toxicity. The aim of this study was to develop a novel drug-device combination tissue scaffold that can be used to deliver the chemotherapeutic agent, docetaxel, into the tissue cavity that is created following radical prostatectomy. The device component investigated consisted of highly porous, poly(dl-lactide-co-glycolide) microparticles made using thermally induced phase separation. A facile method was established for loading docetaxel with high efficiency within one hour. Sustained drug release was observed from the microparticles when placed into a dynamic system simulating tissue perfusion. The drug released from the microparticles into perfusates collected at regular time intervals inhibited colony formation and exhibited sustained cytotoxicity against 3D spheroids of PC3 prostate cancer cells over 10 days. In conclusion, this study demonstrates the concept of combining docetaxel with the biodegradable microparticles at the point of care is technically feasible for achieving an effective drug-device combination tissue scaffold. This approach could provide an effective new approach for delivering adjuvant chemotherapy following radical prostatectomy.

In this study, the response surface methodology (RSM) based on the central composite design (CCD) was used to optimize the preparation condition of polypropylene-grafted maleic anhydride (PP-g-MA) microporous membrane by thermally-induced phase separation (TIPS) method. A mixture of dibutyl phthalate (DBP) and dioctyl phthalate (DOP) was used as diluent. The effect of polymer composition and quenching bath temperature on the morphology and performance of the fabricated microporous membranes was investigated by using RSM. Analysis of variance (ANOVA) was used to determine which variables and interactions between variables had a significant effect on our responses. The ANOVA revealed that the bath temperature was the most significant variable associated with porosity and pure water flux responses and the polymer concentration was the most significant variable associated with tensile response. The obtained results also showed that with increasing the polymer concentration and decreasing the quenching bath temperature, the membrane porosity and pure water flux decreased, whereas the membrane tensile increased. The regression equations were reasonably validated and used to predict and optimize the performance of PP-g-MA membranes within the limits of the variables. Finally, the maximum responses (flux of 115.6 L/m2h, porosity of 62% and tensile of 1.6 MPa) were obtained under the following conditions: polymer concentration of 28.5 wt% and temperature of 329 K. Further, comparison of laboratory-made and commercial membranes in a membrane bioreactor (MBR) system showed that the rate of membrane fouling was decreased by 4.2 times.

Ultrathick battery electrodes are appealing as they reduce the fraction of inactive battery parts such as current collectors and separators. However, thick electrodes are difficult to dry and tend to crack or flake during production. Moreover, the electrochemical performance of thick electrodes is constrained by ion and electron transport as well as fast capacity degradation. Here, we report a thermally induced phase separation (TIPS) process for fabricating thick Li-ion battery electrodes, which incorporates the electrolyte directly in the electrode and alleviates the need to dry the electrode. The proposed TIPS process creates a bicontinuous electrolyte and electrode network with excellent ion and electron transport, respectively, and consequently achieves better rate performance. Using this process, electrodes with areal capacities of more than 30 mAh/cm2 are demonstrated. Capacity retentions of 87% are attained over 500 cycles in full cells with 1-mm-thick anodes and cathodes. Finally, we verified the scalability of the TIPS process by coating thick electrodes continuously on a pilot-scale roll-to-roll coating tool. [ABSTRACT FROM AUTHOR]

The polyamic acid (PAA) and polyvinylpyrrolidone (PVP) blends electrospun fibers were prepared by electrospinning method. PAA with high carbon conversion served as carbon nanofibers; PVP with low carbon conversion served as porogenic sacrificial agent. Then, the PAA-PVP-based carbon nanofibers with well-controlled meso/macro pore structure were obtained via thermally induced phase separation process. The morphology and electrochemical performance of porous carbon nanofibers are investigated by structural analysis and electrochemical measurements. The relationship among pore structure, character of electrolyte and electrochemical performance of porous carbon nanofibers was extensively evaluated. Porous carbon nanofibers derived from PAA-PVP (mass ratio = 5:2) electrospun fibers show adjustable average pore diameter (3.1 nm), high BET specific surface area (743.5 m2 g−1), and average pore volume (0.126 cm3 g−1). The supercapacitor constructed by porous nanofibers as electrode in ionic liquids electrolyte exhibits wide electrochemical stability window (3.4 V), high specific capacity (211.7 F g−1), good power density (2021 W kg−1), and low internal resistance (1.0 Ω). The findings reveal a guideline of the preparation of blending polymer-based porous carbon nanofibers for electrochemical energy conversion and storage. [ABSTRACT FROM AUTHOR]

Efforts have been made in thermally induced phase separation (TIPS) process to modify the morphology of polyvinylidene fluoride (PVDF) membranes in order to improve their permeation performance and mechanical properties. Nevertheless, many methods not only altered the outer surface but also impacted the overall membrane structure, resulting in a trade-off between permeability and mechanical properties. In this study, we utilized a modified TIPS process to refine the outer surface morphology without altering the bulk structure. This was achieved by introducing NaCl in the coagulation bath. The PVDF membranes were fabricated using a dope with water insoluble diluent dimethyl phthalate (DMP) as main solvent and water-soluble additives polyethylene glycol 400 (PEG400)/triethylene glycol (TEG) as pore formers. The inclusion of NaCl in the coagulation bath serves to decrease the solubility of PEG within this medium, owing to the salting-out effect. Consequently, the NaCl concentration in the coagulation bath emerges as a crucial factor in regulating the migration of PEG400 toward the membrane surface. This control mechanism facilitates the precise adjustment of the outer surface morphology in the fabrication of membranes. As the NaCl concentration increases in the coagulation bath, the outer surface of the fabricated membrane transited from a mesh-like structure to a spherulite structure. As 0.5 mol L−1 NaCl was added to the coagulation bath, the membranes displayed a pure water permeability of 1073.9 L m−2 h−1 bar−1 while maintaining a narrow pore size distribution. Compared to the membranes fabricated without NaCl addition, the increment of the PWP contributed to the slight increase in mean pore size from 65 nm to 84 nm. Meanwhile, the water-insoluble diluent DMP was not affected by the addition of NaCl, which means that the bulk structure of the membrane could be maintained. Consequently, the increase in permeability did not compromise the mechanical properties of the membranes. All the membranes fabricated in this study maintained a reasonable tensile strength of approximately 3 MPa. This study introduces a simple and environmental method to increase the permeability effectively and fine-tune the pore size of the TIPS membranes while having little effect on the bulk structure. Furthermore, the study provides valuable insights into how changes in outer surface morphology can impact the pore size and permeability of TIPS PVDF membranes. [Display omitted] • Ultrafiltration PVDF membranes was fabricated by a modified TIPS method. • NaCl coagulation bath could control the outflow of PEG toward membrane surface. • The surface of the membranes could be fine-tuned without altering the bulk structure. • The ultrafiltration membranes present a narrow pore size distribution and high permeability. [ABSTRACT FROM AUTHOR]

Due to the good hydrophobicity and chemical resistance of poly(ethylene trifluoroethylene) (ECTFE), it has been an attractive potential material for microfiltration, membrane distillation and more. However, few porous hydrophobic ECTFE membranes were prepared by thermally induced phase separation (TIPS) for membrane condenser applications. In this work, the diluent, di-n-octyl phthalate (DnOP), was selected to prepare the dope solutions. The calculated Hassen solubility parameter indicated that ECTFE has good compatibility with DnOP. The corresponding thermodynamic phase diagram was established, and it has been mutually verified with the bi-continuous structure observed in the SEM images. At 30 wt% ECTFE, the surface contact angle and liquid entry pressure reach their maximum values of 139.5° and 0.71 MPa, respectively. In addition, some other basic membrane properties, such as pore size, porosity, and mechanical properties, were determined. Finally, the prepared ECTFE membranes were tested using a homemade membrane condenser setup. When the polymer content is 30 wt%, the corresponding results are better; the water recovery and condensed water yield is 17.6% and 1.86 kg m−2 h−1, respectively.

The use of green solvents satisfies safer chemical engineering practices and environmental security. Herein, myristic acid (MA)—a green diluent—was selected to prepare poly- (4-methyl-1-pentene) (PMP) membranes with bicontinuous porous structure via a thermally induced phase separation (TIPS) process to maintain a high gas permeability. Firstly, based on the Hansen solubility parameter ‘distance’, Ra, the effect of four natural fatty acids on the PMP membrane structure was compared and studied to determine the optimal green diluent, MA. The thermodynamic phase diagram of the PMP-MA system was calculated and presented to show that a liquid-liquid phase separation region could be found during the TIPS process and the monotectic point was around 34.89 wt%. Then, the effect of the PMP concentration on the morphologies and crystallization behavior was systematically investigated to determine a proper PMP concentration for the membrane preparation. Finally, PMP hollow fiber (HF) membranes were fabricated with a PMP concentration of 30 wt% for the membrane performance characterization. The resultant PMP HF membranes possessed good performances that the porosity was 70%, the tensile strength was 96 cN, and the nitrogen flux was 8.20 ± 0.10 mL·(bar·cm2·min)−1. We believe that this work can be a beneficial reference for people interested in the preparation of PMP membranes for medical applications.

The formation of porous structures from polymer solutions at the surface in contact with various solid surfaces via a thermally-induced phase separation (TIPS) process is investigated. The pore formation process at the bulk and the surface of the poly(methyl methacrylate)/cyclohexanol solution is simulated with a model based on the phase field method. When the compatibilities between the polymer-rich phase formed by the phase separation and the solid surface are high or low, surface porosity decreases. In contrast, for the solid surface having similar compatibilities with the polymer and solvent, high surface porosity is achieved. This indicates that the compatibility between the solid surface and polymer solution is important, and that optimal compatibility results in high surface porosity. The knowledge obtained in this work is useful to design the coagulation bath component in the membrane preparation process by TIPS for achieving high surface porosity.

Prostate cancer is a leading cause of death in men and despite improved surgical procedures that aid tumor resection, the risk of recurrence after surgery as a result of positive resection margins remains significant. Adjuvant chemotherapy is often required but this is associated with toxicity. Improved ways of delivering highly toxic chemotherapeutic drugs in a more controlled and targeted manner after the prostate has been removed during surgery could reduce the risk of recurrence and avoid systemic toxicity. The aim of this study was to develop a novel drug-device combination tissue scaffold that can be used to deliver the chemotherapeutic agent, docetaxel, into the tissue cavity that is created following radical prostatectomy. The device component investigated consisted of highly porous, poly(dl-lactide-co-glycolide) microparticles made using thermally induced phase separation. A facile method was established for loading docetaxel with high efficiency within one hour. Sustained drug release was observed from the microparticles when placed into a dynamic system simulating tissue perfusion. The drug released from the microparticles into perfusates collected at regular time intervals inhibited colony formation and exhibited sustained cytotoxicity against 3D spheroids of PC3 prostate cancer cells over 10 days. In conclusion, this study demonstrates the concept of combining docetaxel with the biodegradable microparticles at the point of care is technically feasible for achieving an effective drug-device combination tissue scaffold. This approach could provide an effective new approach for delivering adjuvant chemotherapy following radical prostatectomy. [ABSTRACT FROM AUTHOR]

Polycaprolactone (PCL), dicalcium phosphate dihydrate (DCPD) and/or calcium silicates (CaSi) have been used to prepare highly porous scaffolds by thermally induced phase separation technique (TIPS). Three experimental mineral-doped formulations were prepared (PCL-10CaSi, PCL-5CaSi-5DCPD, PCL-10CaSi-10DCPD); pure PCL scaffolds constituted the control group. Scaffolds were tested for their chemical-physical and biological properties, namely thermal properties by differential scanning calorimetry (DSC), mechanical properties by quasi-static parallel-plates compression testing, porosity by a standard water-absorption method calcium release, alkalinizing activity, surface microchemistry and micromorphology by Environmental Scanning electronic Microscopy (ESEM), apatite-forming ability in Hank Balanced Saline Solution (HBSS) by Energy Dispersive X-ray Spectroscopy (EDX) and micro-Raman, and direct contact cytotoxicity. All mineral-doped scaffolds released calcium and alkalinized the soaking medium, which may favor a good biological (osteogenic) response. ESEM surface micromorphology analyses after soaking in HBSS revealed: pure PCL, PCL-10CaSi and PCL-10CaSi-10DCPD kept similar surface porosity percentages but different pore shape modifications. PCL-5CaSi-5DCPD revealed a significant surface porosity increase despite calcium phosphates nucleation (p < 0.05). Micro-Raman spectroscopy detected the formation of a B-type carbonated apatite (Ap) layer on the surface of PCL-10CaSi-10DCPD aged for 28 days in HBSS; a similar phase (but of lower thickness) formed also on PCL-5CaSi-5DCPD and PCL; the deposit formed on PCL-10CaSi was mainly composed of calcite. All PCL showed bulk open porosity higher than 94%; however, no relevant brittleness was observed in the materials, which retained the possibility to be handled without collapsing. The thermo-mechanical properties showed that the reinforcing and nucleating action of the inorganic fillers CaSi and DCPD improved viscoelastic properties of the scaffolds, as confirmed by the increased value of storage modulus and the slight increase in the crystallization temperature for all the biomaterials. A detrimental effect on the mechanical properties was observed in samples with the highest amount of inorganic particles (PCL-10CaSi-10DCPD). All the scaffolds showed absence of toxicity, in particular PCL-10CaSi-10DCPD. The designed scaffolds are biointeractive (release biologically relevant ions), nucleate apatite, possess high surface and internal open porosity and can be colonized by cells, creating a bone forming osteoblastic microenvironment and appearing interesting materials for bone regeneration purposes. Unlabelled Image • PCL acted as a suitable matrix for mineral-doped scaffolds production, allowing the production of biocompatible scaffolds. • TIPS allowed to produce extremely highly porous (approaching 95%) mineral doped-scaffolds. • Incorporation of CaSi and DCPD lead to biointeractive (Ca and OH release) and bioactive (apatite nucleation) scaffolds. • Developed mineral-doped scaffolds may act synthetic extracellular matrices for cell adhesion and proliferation. [ABSTRACT FROM AUTHOR]

Objective(s): The present study aimed to prepare polycaprolactone (PCL) scaffolds with high porosity and pore interconnectivity, in order to copy the microstructure of natural bones using the thermally induced phase separation (TIPS) technique. Materials and Methods: The scaffolds were coated with chitosan (CH), bioactive glass (BG), and gelatin nanoparticles (GEL NPs) and assessed using scanning electron microscopy and Fourier-transform infrared spectroscopy (FTIR). The effects of various coatings on the scaffold characterizations, proliferation, and mineralization of MG-63 osteoblast-like cells were evaluated. Results: The size of the prepared BG and GEL NPs was estimated to be 400 and 234 nanometers, respectively. The porosity and contact angle of PCL/CH/GEL NPs/BG was 74% and 72°, respectively. Weight loss and electron microscopy evaluations indicated the improved degradation rate of the scaffolds and spreading tendency of the cells on the scaffolds when modified as compared to the scaffolds that were purely obtained from PCL. In addition, the in-vitro studies revealed that the MG-63 cells cultured on the PCL/CH/GEL NPs/BG scaffolds showed improved cell proliferation more significantly compared to the scaffolds obtained from PCL, PCL/CH/GEL NPs, PCL/CH, and PCL/GEL NPs. Mechanical examinations also showed that PCL/CH/GEL/BG scaffolds had the highest mechanical strength compared to other groups (i.e., 4.66 Mpa). Cell viability was estimated to be 96.7%, and the alizarin red test indicated the significant improvement of mineralization in the PCL/CH/GEL NP group. Conclusion: According to the results, the PCL scaffolds that were modified by CH/GEL NPs/BG had the high potency to be used as bone tissue engineering scaffolds. [ABSTRACT FROM AUTHOR]

Mullite ceramic foams with high structural complexity, controlled pore structures and low thermal conductivity were manufactured by selective laser sintering (SLS) using core-shell structured polyamide12 (PA12)/fly ash hollow spheres (FAHSs) composites, which were prepared by thermally induced phase separation that exhibit a good flowability and formability for SLS. Crack-free honeycomb green body with intersecting pore channels were fabricated under the optimized processing parameters. Total porosity and closed/open pore size distribution of mullite ceramic foams can be well adjusted by the sintering temperature and PA12 content. The thermal conductivity increased gradually due to increased porosity as decreasing sintering temperature, while decreased probably due to phase change with an increasing PA12 content. The relatively low thermal conductivity of 0.08 W/(m▪K) was obtained when added 30 wt% PA12 content, with a high porosity of 85.0 ± 0.2% and compressive strength of 2.61 ± 0.2 MPa. The understanding pore structure characteristics will help design the high-porosity mullite ceramic foams with controlled pore structures and low thermal conductivity. [ABSTRACT FROM AUTHOR]

The co-extrusion technique employing a triple-orifice spinneret has been found to be an effective method to regulate the membrane pore size and surface structure. This is achieved by simultaneously extruding another solvent at the outer surface of the nascent polymer membrane. In this study, co-extrusion technology was employed to modify the outer surface structure of the polyketone (PK) hollow fiber membrane to enhance membrane permeance. By extruding various solvents at the outermost layer of the triple-orifice spinneret, besides the interaction among PK, diluent, and extruded solvent, it was emphasized that the viscosity of the outer solvent significantly influenced the penetration process and consequently affected the microstructure of the membrane surface. In addition, it was found that the higher water permeance was mainly attributed to the increased surface porosity rather than the slightly increased membrane pore size. The penetration of extrusion solvent propylene carbonate (PC) with low viscosity resulted in a porous outer surface with higher surface porosity, leading to high water permeance (2430 L m−2h−1bar−1). Furthermore, the air gap distance was optimized, and its effects on membrane structure, pore size, water permeance, and strength were discussed. This work provides a guideline for selecting preparation parameters and extrusion solvents to prepare PK membranes with high permeance. [Display omitted] • High-permeance PK HFMs were prepared by triple-orifice spinneret (2400 L m−2h−1bar−1). • Porous structure formed at outer surface of PK HFMs when solvent were extruded. • The effect of viscosity of extruded solvent on surface structure was discussed. • The relationship between the surface porosity and the flux was revealed. • The effect of air gap distance on penetration of extruded solvent was studied. [ABSTRACT FROM AUTHOR]

Poly (4-methyl-1-pentene) (PMP) hollow-fiber membranes (HFMs) with bi-continuous structure and high plasma-leakage resistance were successfully prepared via thermally induced phase separation using binary diluents of nontoxic paraffin oil (PO) and oleic acid (OA) for oxygenation. The phase separation mechanism of the PMP HFM with 30–40 wt% PMP shifted from solid–liquid to liquid–liquid as the PO/OA mass ratio was increased, changing its flaky crystal structure to a bi-continuous or cellular structure. The effects of the air-gap distance, take-up speed, and PMP concentration on the HFM structure and performance were also investigated. The results showed that a shorter air-gap distance and higher take-up speed reduced the pore size and gas permeability of the membranes. Under the optimal conditions (PMP concentration: 40 wt%, PO/OA mass ratio: 49/11, take-up speed: 60 rpm air-gap distance: 10 mm), PMP HFM exhibited excellent gas permeability (N 2 flux: 2.4 mL/(bar·cm2·min) or 533 GPU), mechanical properties (tensile strength: 10.4 MPa; elongation at break: 150.6 %), and plasma-leakage resistance (leakage time: >5900 at an external liquid and internal gas pressures of 0.1 and 0.08 MPa, respectively). Therefore, this study has significant implications for the large-scale production of PMP HFMs. [Display omitted] • PO/OA was used as the binary nontoxic diluent for PMP HFMs. • OA promoted L–L phase separation, resulting in membranes with bi-continuous structure. • Small air-gap distance and high take-up speed decreased the pore size and N 2 flux. • Optimal PMP HFM had excellent gas permeability and plasma-leakage resistance. • PMP HFMs prepared using green PO/OA diluents have great potential for ECMO. [ABSTRACT FROM AUTHOR]

Due to the excellent solvent resistance properties of polyketone (PK), the traditional non-solvent induced phase separation (NIPS) preparation process is both highly toxic and complex. In this work, we successfully and efficiently prepared PK hollow fiber membranes using the thermally induced phase separation (TIPS) method, capitalizing on a low-toxicity diluent system of polyethylene glycol 300 (PEG300) and triethylene glycol (TEG). Moreover, by simply adding TEG to the diluent, we achieved a reduction in the spinning temperature, resulting in membranes that display an interconnected structure formed through the liquid-liquid phase separation process. We systematically investigated the impact of the TEG ratio in the diluent, PK concentration, and propylene carbonate (PC) ratio in the bore liquid on the phase diagram, membrane morphology, and characteristics of PK membranes. Increasing the PC ratio in the bore liquid significantly improves the inner surface porosity due to PC penetration into the dope solution, leading to high water permeability. Additionally, the resulting PK membrane exhibits exceptional resistance to organic solvents. This work introduces a novel approach to lower the spinning temperature for PK membrane preparation in the TIPS process while preserving the membrane structure and properties. [Display omitted] • PK HFMs was prepared with low-toxic mixed diluent system via TIPS method. • The spinning temperature was significantly lowered with the addition of TEG. • The effects of PK concentration and bore liquid on membrane preformance were studied. • The resultant PK HFMs exhibited high water permence and good solvent resistance. [ABSTRACT FROM AUTHOR]

The non-isothermal crystallization behavior of poly(vinylidene fluoride) (PVDF) in dialkyl phthalate diluents during the thermally induced phase separation (TIPS) process was investigated by differential scanning calorimetry (DSC) at various cooling rates. Dialkyl phthalates with different alkyl chain-length, namely dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP), were used as the diluent. The effects of alkyl chain-length of dialkyl phthalate and cooling rate on the non-isothermal crystallization behavior as implied by the Avrami analysis modified by Jeziorny and Mo’s analysis were determined. The values of half-time, t1/2, and the parameters Zc and F(t), which characterized the kinetics of non-isothermal crystallization, showed that the crystallization rate increased with the increase of the alkyl chain-length of dialkyl phthalate due to the lower compatibility between PVDF and dialkyl phthalate. Moreover, the alkyl chain-length of dialkyl phthalate also has a great impact on the compact spherulitic structure of PVDF membranes prepared from different PVDF/dialkyl phthalate blends. With the decrease of the alkyl chain-length of dialkyl phthalate, the number of spherulites increased and the size of spherulites became smaller. This research thus not only proves the effects of alkyl chain-length of dialkyl phthalate on the non-isothermal crystallization behavior of PVDF, but also provides a systematic strategy to evaluate a single diluent during the TIPS process.

Graphical abstract Highlights • The PVDF membrane with high permeability and strength was fabricated via TIPS. • The formation of TIPS-NIPS for the membrane with a thin skin-layer was proposed. • The strengthening mechanism of tenon-connection and adhesive effect was proposed. • The adhesive effect of PVB prevented its abscission from the polymer matrix. • The as-prepared membranes showed a β-phase. Abstract In this work, thermally induced phase separation (TIPS) method was adopted to manufacture polyvinylidene fluoride (PVDF) blend hollow fiber microfiltration membrane with tenon-connection structure, which is used to fasten in Chinese traditional building by the stronger friction between rabbet and mortise, for water treatment by blending polyvinyl butyral (PVB). In this microstructure formation process, the distribution of PVB within the matrix and its regulatory role were investigated. Especially, the comprehensive effect of rabbeting and PVB adhesion on strength (The maximum breaking strength reached 17.08 MPa) was discussed. The results showed that a suitable PVB will markedly reduce the thickness of skin-layer close to the outside surface even for the solid-liquid (S-L) phase separation while the excessive PVB result in a thick skin-layer. Besides the strength, PVB markedly improved the hydrophilicity and permeability of the membrane. The breaking strength is more than 8 MPa, the maximum pure water flux is as high as 929.23 L m−2 h−1 and the rejection rate of carbon particles is nearly 100% even the polymer content is only 22%. In addition, the membrane showed a β-phase and an improved anti-fouling capacity. The investigation presented a simple way to regulate microstructure, enhance mechanical strength, flux and anti-fouling capacity of the membrane via the TIPS process for water treatment. [ABSTRACT FROM AUTHOR]

A novel superhydrophilic and underwater superoleophobic poly (acrylonitrile-co-methyl acrylate) (P(AN-MA)) microfiltration membrane (MF) was processed. In order to create micro/nanostructured roughness surface and improve the hydrophilicity of the membranes, the thermally induced phase separation (TIPS) method combined with surface hydrolysis reaction method were adopted. The obtained membrane is noted for symmetrical and hierarchical micro/nano-structure with excellent superhydrophilicity and underwater superoleophobicity. It can efficiently separate surfactant-free and surfactant-stabilized oil-in-water emulsions with ultrahigh water fluxes, which is up to 4341 L/m 2 h under a low operating pressure (0.02 MPa). The oil content in the filtrate is below 5 ppm after one time separation, showing significant applicability for energy-saving filtration. In addition, the hydrolyzed PAN-based membrane has superior antifouling property and unconspicuous oil adhesion property, which is noted for excellent reusability. This work provides a simple and green technology to fabricate superhydrophilic PAN-based MF membrane for highly efficient separation of oil-in-water emulsions. [ABSTRACT FROM AUTHOR]

Polyphenylene sulfide (PPS) membranes were fabricated via a thermally induced phase separation method using mixed diluent of epsilon-caprolactam (CPL) and diphenyl sulfone (DPS). The effect of changing the CPL/DPS weight ratio on the structure and properties of prepared PPS membranes were investigated. The morphologies and performances of obtained PPS membranes were characterized by scanning electron microscopy, static water contact angles, mechanical strength, porosity, permeability and salt rejection rate. The characterized results showed that the morphologies of PPS membrane changed from cellular, bi-continuous to spherulitic structure with the increase of CPL/DPS mass ratio. PPS membranes exhibited the excellent stability and high salt rejection ratio in VMD experiments. The largest permeate flux stabilized at 10.63 L/(m²·h¹) and the highest salt rejection remained above 98.9% after operating for 10 h. [ABSTRACT FROM AUTHOR]

In this study, isotactic polypropylene hollow fiber membranes were fabricated using co-diluent of di-n-butyl phthalate and dioctyl phthalate via thermally induced phase separation method. A coarsening model in terms of the momentum, mass and heat transfer during the spinning process was established to describe the effect of the spinning temperature on the membrane. The increasing spinning temperature increased the predicted solidification time and decreased phase separation time simultaneously. Moreover, the diluent evaporation on the outer surface is dramatically influenced by temperature. The prepared hollow fiber membranes were used to concentrate NaCl saline water of 30 up to 80 g/L about 100 h to evaluate the performance of air gap membrane distillation process in terms of permeation flux and gain output ratio. The salt rejection always exceeded 99.9% in the concentration experiment. [ABSTRACT FROM AUTHOR]

Abstract As a pivotal part of lithium-ion batteries, separator is supposed to have high strength, thermal stability and excellent wettability. In this study, polyformaldehyde/cellulose nanofibers blend separators are firstly prepared via thermally induced phase separation to improve the performance, especially the safety of LIBs. The polyformaldehyde/cellulose blend separators show considerable tensile strength (116 MPa) and Young's modulus (6.07 GPa) owing to the high crystallinity and high performance of polyformaldehyde and cellulose. In particular, benefiting from their abundant polar groups and highly porous structure, the polyformaldehyde/cellulose blend separators possess high electrolyte uptake (412%) and small contact angle (19°) as compare to the commercial polyethylene separator (115%, 58°). Moreover, the thermal treatment tests indicate that the polyformaldehyde/cellulose blend separators are thermally stable at as high temperature as 180 °C. And the polyformaldehyde/cellulose blend separators show higher ionic conductivity (1.39 mS cm−1) and lower interface resistance (49.5 Ω) than polyethylene separator (0.76 mS cm−1, 136.4Ω). As expected, the LiFePO 4 /Li cell with polyformaldehyde-20-cellulose blend separators exhibit the best stable cycling performance and improved rate performance than PE separator, especially at high rate. In summary, the polyformaldehyde/cellulose blend separators are promising new kind of separator for LIBs with high safety and enhanced performance. Graphical abstract Image 1 Highlights • This is a first report about polyformaldehyde/cellulose blend separator. • The blend separator shows high porosity of 78% and good electrolyte wettability. • High ionic conductivity of 1.39 mS cm-1 and lower interface resistance of 49.5 Ω. • Outstanding tensile strength of 116 MPa and very high Young's modulus of 6.07 GPa. • The cell with blend separator shows 0.059% capacity fading per cycle at 200 mA g-1. [ABSTRACT FROM AUTHOR]

In this study, a melt processable poly(acrylonitrile-co-methyl acrylate)(P(AN-MA)) copolymer was used as membrane matrix, caprolactam (CPL) and glyceryl triacetate (GTA) were used as an ecofriendly mixed diluent. P(AN-MA) membranes with inter-connected sponge structure and porous surface were successfully fabricated via thermally induced phase separation (TIPS). The optimum ratio of CPL/GTA in the mixed diluent was 1:1 wt.%. Even though the concentration of P(AN-MA) was up to 25 wt.%, the surface of membrane still exhibited microporous structure. When the concentration of P(AN-MA) was 15 wt.%, the membrane formed in 20 °C air bath showed the highest water flux of 6802 L/m²h. With the increasing of copolymer content or cooling rate, the pore size decreased. In addition, all of the P(AN-MA) membranes exhibited a rejection to carbon ink more than 90 wt.%. The average pore size of the membranes was less than 270.5 nm, and the tensile strength was more than 2.8 MPa. It is anticipated that the facile and green technology TIPS will bring the P(AN-MA) membrane a step closer for practical applications, including clean-up of oil spills, waste water treatment, fuel purification, and separation of commercially relevant emulsions. [ABSTRACT FROM AUTHOR]

Polyphenylene sulfide (PPS) hydrophobic micro-porous flat sheet membranes were fabricated with diphenyl ketone (DPK) and benzoin (BZ) as mixed diluent via thermally induced phase separation (TIPS). It was found that the mass ratio of DPK/BZ had a strong influence on the structure and property of PPS membranes. As DPK content increased, the interaction between PPS and diluents reduced linearly and the membrane micro-structures changed from honeycomb, bi-continuous to spherical particle structure via liquid-liquid (L-L) phase separation process. Herein, the prepared PPS micro-porous membranes were used in vacuum membrane distillation (VMD) for the first time, and they showed the strong hydrophobicity and high salt rejection ratio. Especially, the membrane prepared from the mixed diluent of 15 wt% DPK and 85 wt% BZ with the bi-continuous network structure and Berberis thunbergii var. atropurpurea Chenault leaf-like structure achieved the maximum permeate flux of 22.8 L/m −2 h −1 and the highest salt rejection of 99.99%. Most importantly, the membrane with Berberis thunbergii var. atropurpurea Chenault leaf-like leaf structure performed excellent long-term stability in corrosive water membrane distillation (MD) experiment (3.5 wt% NaCl and 10 wt% NaOH as feed solution). Those results show the potential application of this novel type of membrane in the treatment of corrosive sewage. [ABSTRACT FROM AUTHOR]