Solvent Treatment Research Articles

Determination of stability and activity of immobilized lipase for transesterification reaction in fluorous solvent and deducing the reaction mechanism by molecular docking study

The objective of the present study was to immobilize lipase and use it for transesterification reaction in a fluorous solvent. Polymeric substance tylose (Tyl) was chosen as immobilization support. Tylose immobilized lipase from Candida rugosa (CRL) was subjected to fluorous solvents treatment and was found most stable in perfluorooctane (PFO). The immobilized Tyl-CRL was characterized for protein loading, solvent stability, surface morphology, restoration of secondary structure, and thermal stability. Immobilized CRL was further applied for the synthesis of phenethyl propionate in a fluorous solvent. All reaction parameters were optimized using the response surface method (RSM). Optimized reaction parameters were substrate ratio 1:3, immobilized lipase quantity 30 mg, and temperature 45 °C. Prepared biocatalyst was evaluated for recyclability, and it was found that catalytic activity decreased by 77 % up to the fifth recycle run. The optimized synthesis protocol showed a wide substrate scope. The docking study showed very good interaction of substrates with lipase supporting the experimental findings. The developed methodology offers a safer, more efficient approach to synthesizing various esters used as nature-identical flavors.

EVALUATION OF THE GRAPHENE DISPERSIONS FOR KEVLAR FABRICS FUNCTIONALIZATION OBTAINED BY THE LIQUID-EXFOLIATION OF GRAPHITE

The process where pristine graphite is subjected to a solvent treatment seems simple and scalable and has attracted the attention of researchers over many years. However, for successful exfoliation, overcoming the van der Waals attractions between the adjacent layers of graphite is necessary. Over time, several methods have been created to overcome the attraction between layers. Graphene’s liquid phase exfoliation (LPE) occurs due to the strong interactions between the solvent molecules and the basal planes of graphite, overcoming the energetic resistance to exfoliation and subsequent dispersion. Ultra sonication used for exfoliation can produce single or few layered graphene flakes. During sonication the sound waves propagate through liquid medium in alternating high- and low-pressure cycles, strong mechanical and thermal energy released by acoustic cavitation results in splitting up large particles into fine ones and dispersing them. Simultaneous insertion of solvent and/or intercalation molecules in between the graphite layers takes place supporting graphite separation into graphene layers. ; The dispersion capacity of graphene flakes depends on how appropriate the solvent properties are to the corresponding properties of graphene, such as surface tension, Hildebrand, and Hansen solubility parameters. Only certain solvents can disperse graphene well and form a dispersion appropriate for specific future applications. In addition, after exfoliation by ultra sonication graphene flakes aggregation due to the van der Waals attractions must be overcome to prepare in long-term stable dispersions of nanometres-size graphene sheets. ; The research has focused on the preparation of stable dispersion ready for transfer without intermediate processes to the Kevlar fabrics. An experimental comparison of the potentials of the 4 solvents for the application resulted in three corresponding to the intended use, two of them examined in detail, supplementing the composition of the LPE liquid medium with triethanolamine to obtain sufficient performance graphene coverage on Kevlar textile fibres.

Optimisation of powder extrusion moulding process for thick ceramic electrodes of LiCoO2 for enhanced energy-density lithium-ion batteries

Lithium-ion batteries are widely used in portable electronic devices because of their high energy and power density. To enhance the energy density of these batteries, one strategy involves increasing the active material loading by increasing the thickness of the electrodes. In previous studies, we demonstrated that powder extrusion moulding (PEM) is a scalable and efficient method for producing additive-free LTO and LFP ceramic electrodes, which exhibit remarkable electrochemical performance with thicknesses up to 500 μm. This study focuses on the preparation and optimisation of the entire manufacturing process for thick ceramic electrodes of LiCoO2 (LCO) with a high mass loading of 180 mg cm−2 using the PEM process. Different powder loadings of mixtures of LCO and a thermoplastic multi-component binder were explored to obtain a formulation suitable for rheology. The optimal formulation comprises 60 vol% of powder. After binder removal via a combination of solvent and thermal treatment, followed by air sintering, parts with varying porosities were obtained. Striking a balance between porosity and thermal degradation is crucial for achieving optimal electrochemical behaviour. Electrochemical evaluations of the electrodes sintered at 900 °C and 1000 °C revealed areal capacity values as high as 17 mAh cm−2 at C/25 and 7 mAh cm−2 at C/6.25, respectively. These values far exceed the 1−2 mAh cm−2 obtained from commercial LCO electrodes. These results indicate a strategy for the production of electrodes to fabricate lithium-ion batteries with a low ratio of inactive materials and, therefore, with higher energy densities.

Solvent-Reconstructed Interface That Enhances Light Out-Coupling in Quasi-Two-Dimensional Perovskite Light-Emitting Diodes.

Light management is critical to maximizing the external quantum efficiency of perovskite light-emitting diodes (PeLEDs), but strategies for enhancing light out-coupling are typically complex and expensive. Here, using a facile solvent treatment strategy, we create a layer of lithium fluoride (LiF) nanoislands that serve as a template to reconstruct the light-extracting interfaces for PeLEDs. The nanoisland interface rearranges the near-field light distribution in order to maximize the efficiency of internal light extraction. With the proper adjustment of the nanoisland size and distribution, we have achieved an optimal balance between charge injection and light out-coupling, resulting in bright, pure-red quasi-two-dimensional PeLEDs with a 21.8% peak external quantum efficiency.

Effect of Aggregation Structure on Capacitive Energy Storage in Conducting Polymer Films.

Conducting polymers (CPs), a significant class of electrochemical capacitor electrode materials, exhibit exceptional capacitive energy storage performance in aqueous electrolytes. Current research primarily concentrates on enhancing the electrical conductivity and capacitive performance of CPs via molecular design and structural control. However, the absence of a comprehensive understanding of the impact of molecular chain spatial order on ion/electron transport and capacitive performance impedes the development and optimization of advanced electrode materials. Here, a solvent treatment strategy is employed to modulate the molecular chain spatial order of PEDOT : PSS films. The results of electrochemical performance tests and Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) show that Poly(3,4-ethylenedioxythiophene) : poly(styrenesulfonic acid) (PEDOT : PSS) films with both face-on and edge-on orientations exhibit exceptional electronic conductivity and ion diffusion efficiency, with capacitive performance 1.33 times higher than that of PEDOT : PSS films with only edge-on orientation. Consequently, molecular chain orientations conducive to charge transport not only enhance inter-chain coupling, but also effectively reduce ion transport resistance, enabling efficient capacitive energy storage. This research provides novel insights for the design and development of higher performance CPs-based electrode materials.

Preparation of high antioxidant nanolignin and its application in cosmetics

Lignin, as a natural polyphenol, displays anti-oxidant activity by trapping and binding free radicals through its free phenolic hydroxyl groups. However, the most accessible form, industrial lignins, generally has low phenolic hydroxyl content, which severely limits their application value and scenarios. Herein, we showed that potassium-glycerate deep eutectic solvent (PG-DES) treatment can be combined with laccase oxidation to afford prepared high antioxidant lignin nanoparticles (HA-LNPs) with notably improved anti-oxidant activities benefiting from both the enhanced phenolic hydroxyl content 170.8 % and reduced average particle size (59.0 nm). At concentrations as low as 60 μg/mL, HA-LNPs showed favorable effects in promoting collagen formation. When HA-LNPs were used as an active ingredient in the anti-aging mask formulation, the reactive oxygen species (ROS) scavenging activity of mask samples containing 0.4 % HA-LNPs reached 37.2 %. The data suggest great promise of HA-LNPs as a natural antioxidant for formulating in anti-aging skin care products.

Comparative assessment of pre-treatment techniques and process economics on marine seaweed, Gelidium pusillum, for enhanced bioethanol production

Many researchers are actively investigating different pre-treatment methods on alternative energy sources for sustainable production of bioethanol. With abundant carbohydrates and ease of cultivation, Gelidium pusillum, seaweed biomass has gained attention as a bioethanol feedstock. In the present study, various combinatorial pre-treatment methods like ultrasonic-acid treatment, microwave-alkali treatment, and steam-organic solvent treatment were carried out on seaweed biomass and compared for their efficiency in bioethanol production. Physico-chemical changes of biomass were characterized using Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and X-ray Diffraction. Among all pre-treatment methods, microwave-alkali treatment was found to be the most effective one and yielding fermentable sugars, sugar utilization efficiency, and ethanol concentration of 395 mg/g, 78.33 ± 0.98%, and 5.7 ± 0.19 g/L, respectively. Additionally, the process-economic analysis showed that Gelidium pusillum and microwave-alkali treatment could be scaled up to the industrial level with a production cost of $1.40 per liter of ethanol with minimal ecological impact.

Highly sensitive determination of acyclovir using Ti3C2-CS-MWCNTs-COOH/GCE composite as a sensing platform

Acyclovir (Acyclovir, ACV) is an antiviral drug which, despite its favorable safety profile, can have systemic adverse effects, following improper use. This study prepared a clay-like two-dimensional transition metal carbide Ti3C2 by etching Ti3AlC2 with LiF and HCl. Carboxylated multi walled carbon nanotubes (Carboxylated multi-walled carbon nanotubes, MWCNTs-COOH) were combined with Ti3C2 using chitosan (Chitosan, CS) as solvent and ultrasonic treatment. The nanocomposite was then modified onto the surface of a glassy carbon electrode (Glassy carbon electrode, GCE) to develop an electrochemical sensor for the detection of ACV. The Ti3C2-CS-MWCNTs-COOH/GCE nanocomposite was characterized by X-ray diffractometry (X-ray diffractometry, XRD), scanning electron microscope (Scanning electron microscope，SEM), and cyclic voltammetry (Cyclic voltammetry，CV), as well as the electrochemical impedance method (Electrochemical impedance，EIS). The successful preparation of Ti3C2-CS-MWCNTs-COOH, and the good electrochemical performance of the electrode were verified. Linear scanning voltammetry (Linear scan voltammetry，LSV) was used to quantify the ACV. The linear range of the method is wider than other works (0.05 ∼ 20.0 and 20.0 ∼ 500.0 μM), with a low detection limit (0.088 μM). The sensor achieves sensitive detection of ACV and can be used for the analysis of ACV in pharmaceutical and urine dosage forms, with recoveries of 95.5∼97.6% and 95.6∼97.5%, respectively. For the first time, this sensor utilizes clay-like Ti3C2 with a larger specific surface area in combination with MWCNTs-COOH for ACV detection, which exhibits excellent immunity to interference, repeatability, reproducibility, and stability. This method provides a rapid and sensitive method for the determination of ACV, and lays foundations for developing miniaturized field rapid test detectors.

In-situ welding and thermal activation enabled robust nanofibers based triboelectric nanogenerator for sustainable energy harvesting

Nanofiber-based triboelectric nanogenerators (TENGs) show great promise in energy harvesting and sensing applications. However, the poor strength and the instability of the nanofiber structures lead to the constraints on the durability and the lack of stability in the output performance. In this study, BaTiO3@PVDF-HFP nanofibers were prepared by electrospinning, in which BaTiO3 nanoparticles enhanced the charge trapping ability of the nanofibers and provided nucleation sites for β-phase growth. Subsequent solvent and annealing treatment in-situ welded the nanofibers, which greatly improved the mechanical strength and stability of the nanofiber membranes. The annealing process further thermally activated the electroactive β-phase in the PVDF-HFP, which increased the surface charge density of the nanofibers. A flexible TENG based on BaTiO3@PVDF-HFP-p nanofiber was prepared to harvest mechanical energy, which could achieve a maximum output of 482.5 V and 1.9 W m−2, the voltage is more than 1.2–1.5 times higher compared to uncrosslinked nanofibers. The BaTiO3@PVDF-HFP-p-based TENG maintains ultra-stable Voc generation over 7000 cycles compared to the nanofibers without solvent and annealing treated. Finally, its practical application in harvesting ambient mechanical energy was demonstrated, which can harvest wind energy to power LEDs and small electronic devices such as temperature and humidity sensors.

Hurdle approach of plasma-activated water pretreatment with debittering treatment on naringin and limonin content of sweet orange peel powder

The current study focused on novel approaches for plasma-activated water treated sweet orange peel waste through the use of various food-grade debittering agents (salt, alkali, and solvent). Among the different methods investigated, solvent treatment with acetone at a ratio of 1:10 (sample: solvent, DSL2) achieved a greater reduction in bitterness causing compounds naringin from 0.59 to 0.41 mg/g and limonin 1.30 to 1.17 mg/g. Moreover, the hurdle impact of both and debittering treatment was effective in reducing the total terpenoid content from 290.89 mg LE/100 g to 230 mg LE/100 g and anti-nutrients, tannin (289.20 mg/100 g to 109.63 mg/100 g), phytic acid (52.22 mg/100 g to 22.55 mg/100 g). The saponin was not found in the treated samples. Solvent treatment decreased total phenols from 163.46 ± 2.54 to 115.81 ± 5.02 mg GAE/100 g and total flavonoids from 662.23 ± 4.53 to 548.48 ± 2.98 mg QE/100 g. Similarly, FRAP (Ferric reducing antioxidant power) decreased from 58.87 ± 1.57 to 38.08 ± 1.96 μg AAE/g and DPPH (2, 2-Diphenyl-1-picrylhydrazyl) (%) from 151.06 ± 3.07 to 123.81 ± 2.46. Optimization of all treatment conditions was accomplished using a full factorial design. Treatment at a ratio of 1:10 (sample: salt, DS2) was determined to be the most optimized condition, taking into account all parameters (total phenols, total flavonoids, total terpenoid content, naringin, limonin, hesperidin, antinutrients and antioxidant activities) including sensory evaluation. Debittered sweet orange peel powder obtained through this process demonstrated higher acceptability for functional and novel food product development.

Sustainable Development in Dye Waste Managemen : A Comparative Study on the Effectiveness of Adsorption and γ-Radiolysis

Pyrromethene 567 (PM567), a BODIPY class of dye; is widely used in medicine, chemistry, material science, and high-power dye lasers. During its use, PM567 dye waste is generated in ethanol solvent which needs to be treated before its disposal. In our study, we -radiolysis, an advanced oxidation process (AOP), and adsorption, a simple and easy option. Interestingly, -radiolysis were not efficient for dye effluent treatment in organic solvents. This inefficiency was attributed to competing reactions leading to the scavenging of dye-degrading radicals. -dose rate (3.5 kGy) feasible in the system; 62% is the maximum removal efficiency achieved by this method. For a comparison, we also investigated the adsorption efficiency of PM567 dye from ethanol solvent using commercially available adsorbents. Among these, powdered activated carbon (PAC) demonstrated the highest removal efficiency, reaching 95%, much higher than that of -radiolysis method. In line with the pursuit of sustainable development, we synthesized granular activated carbons (AC1, AC2, AC3) from coconut shells, a lignocellulosic biowaste. The characterization of these carbons revealed that AC3, with a higher iodine value and CCl4 activity, possessed a systematic pore structure (SEM analysis), a larger specific surface area (1708 m2 .g-1), and a higher micro-pore volume (0.61 cc.g-1). AC3 hence, emerged as the most effective adsorbent, achieving 95% efficiency comparable to PAC.

Model-based process intensification of deep eutectic solvent treatment of eucalyptus slabs for lignin extraction and pulp production

This work revealed the reaction characteristics in the delignification process of eucalyptus slabs catalyzed by acidic deep eutectic solvent (benzyltriethylammonium chloride/formic acid) from the perspective of heterogeneous reactions. The limitation of internal diffusion on delignification process cannot be ignored. Afterwards, a kinetic model based on cell wall structure was proposed to describe the relationship between the delignification degree and reaction conditions, and it also hold excellent predictive ability for lignin removal, carbohydrate retention and solid residue yield. Compared with other reported kinetic models, this novel model not only took into account all operational parameters of reaction process, but also can be applied to the entire reaction process without the need for segmentation. Besides, an essential requirement based on the developed model was a 44.40 wt% formic acid concentration and a temperature of 130 °C, when the purpose of DES treatment was pulping. Generally, this work could provide guidance on process adjustments and product quality control during the DES processing.

Ternary Phase-Field Simulation of Poly(vinylidene fluoride) Microporous Membrane Structures Prepared by Nonsolvent-Induced Phase Separation with Different Additives and Solvent Treatments.

In this study, an existing ternary membrane system based on nonsolvent-induced phase separation (NIPS) with a phase-field model was optimized. To study and analyze the effects of different additives on the formation of the skin layer and the effects of the three solvents on membrane characterization under the same conditions, two-dimensional simulations of the relevant parameters of a poly(vinylidene fluoride) (PVDF) membrane system were performed. The specific application of quaternary substances in ternary membrane systems was elaborated by determining the cohesive energy density between the additives and solvents, followed by the interaction parameters χ under the joint effect of the two. The results showed that the PVDF microporous membrane formed a dense surface layer at the mass transfer exchange interface, and with an increase in the poly(ethylene glycol) (PEG) concentration, the phase separation of the skin layer was predominantly transformed from liquid-solid partitioning to liquid-liquid partitioning; the number of membrane pores increased with increasing poly(vinylpyrrolidone) (PVP) concentration. The N,N-dimethylacetamide (DMAc) solvent system had the most stable thermodynamic properties; the dimethyl sulfoxide (DMSO) solvent system had mostly large pores running through the membrane and exhibited a porous structure. Related experiments also validated the model. Therefore, this model can be applied to other PVDF ternary membrane systems to better understand the structural development of microporous PVDF membranes under different conditions.

Solvent-free microfabrication of thin film device using the focused ion beam

We introduce a novel fabrication technique for thin film devices, utilizing Focused Ion Beam micro-machining. Unlike conventional methods requiring post processes such as etching or solvent treatment, this method involves creating a pre-patterning step-like structure on the substrate before growing the thin film, achieving the desired device pattern right after thin film deposition. As an example, we fabricated devices with VO2 thin film of which electrical transport properties are examined. The VO2 devices exhibit robust metal-insulator transition behavior and V-I characteristics, indicating the high quality of the patterned devices. The results indicate that our approach enables intricate patterning, comparable to conventional e-beam lithography, without the risk of sample degradation. The simplicity, stability, and versatility of this technique suggest new possibilities for thin film device fabrication.

Effect of Treatment Time on Deep Eutectic Solvent Treatment of Scots Pine Wood

Aim of study: The influence of the treatment time (1 hour, 2 hours, and 3 hours) on the deep eutectic solvent (DES) treatment of Scots pine (Pinus sylvestris L.) wood is investigated in this study. 
 Area of the study: Determination of DES performance on the Scots pine wood chemical structure.
 Material and methods: Choline chloride (ChCl) and lactic acid (LA) mixture with molar ratio of 1:10 (w:w) was used as a DES solvent. Treatments were carried out in an autoclave at 121 °C. The effects of DES treatment on the properties of wood and lignin samples of Scots pine were determined according to the relevant standards.
 Main results: The delignification ratio, lignin purity, and lignin yield in the 3h-treated sample were determined to be 79.78%, 86.43%, and 82.48%, respectively. The crystallinity index (CrI) was increased from 55.87% to 71.58% with 3 h DES treatment. Brunauer-Emmett-Teller (BET) analysis results showed that the surface area of the sample increased with 3-h DES treatment (from 3.095 m2/g to 3.621 m2/g). The 1-hour DES-treated sample yielded the lightest colored lignin (L*: 71.62). 
 Research highlights: Treatment time of Scots pine wood during DES treatment has a significant effect on the wood and lignin properties

Engineering 2D Mg-Al-layered double oxides with highly dispersed and enhanced basic sites for efficient ambient NO2 reactive removal

The release of nitrogen dioxide (NO2) into the atmosphere significantly contributes to air pollution, posing threats to both the environment and human health. Selective adsorption technologies have gained attention for their potential to mitigate NO2 emissions under ambient conditions. However, certain solid adsorbents lack accessible active basic sites, a crucial requirement for high NO2 adsorption capacities due to the acidic nature of NO2. Metal-based layered double oxides (LDOs), derived from layered double hydroxides (LDHs), show promise for ambient NO2 adsorption due to their layered structures, strong basic properties, and adjustable adsorption affinity. In this study, we synthesized a series of M-Al-LDO/A (M = Ni, Co, and Mg) using a facile aqueous miscible organic solvent treatment (AMOST) method. The newly synthesized M-Al-LDO/A exhibited a 2D nano flower-like morphology with expanded surface area, increased pore volume, and enhanced accessible basic sites. Dynamic breakthrough experiments demonstrated the exceptional NO2 adsorption capacity of Mg-Al-LDO/A (4.67 mmol g−1) under ambient conditions, surpassing Mg-Al-LDO/CP (0.13 mmol g−1) synthesized from the conventional method by more than 35 times. Temperature-programmed desorption (TPD) results and spectroscopic analyses revealed that the improved NO2 capacity of Mg-Al-LDO/A resulted from the highly dispersed and increased basic sites (Mg-O2-). These findings hold promise for advancing efficient and environmentally friendly NO2 adsorption materials, critical for addressing the challenges posed by NO2-induced air pollution and safeguarding air quality.

Enhancing the photovoltaic responses of MAPbI3 poly-crystalline perovskite films via adjusting the properties of PEDOT:PSS hole transport material with a low-polarity solvent treatment process

The surface and electrical characteristics of the poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) materials are manipulated using a low-polarity solvent treatment process, which influences the formation and nucleation/crystal growth process of the CH3NH3PbI3 (MAPbI3) perovskite films and thereby determining the crystal orientation and grain size. The hydrophilicity of the PEDOT:PSS composite material fabricated on the ITO/glass sample is reduced with the xylenes solvent treatment or a hexamethyldisilazane:xylenes solvent mixture treatment, which can be used to form the photo-active perovskite crystals and thereby reducing the photocurrent hysteresis of the fabricated perovskite based photovoltaic devices. It is worthwhile to mention that the non-perfectness of closed-loop in the photocurrent density-voltage curves under the forward and backward scans can be used as an indicator to assess the properties of the MAPbI3 films. Our findings can facilitate the development of perovskite based optoelectronic devices.

Insoluble Network Skeleton and Soluble Components of Nylon 6,6-Sputtered Nanoparticles: Insights from Liquid-State and Solid-State NMR Analysis.

In this study, we performed a detailed analysis of -sputtered-nylon 6,6 plasma polymer nanoparticles (NPs). Following a previous study using standard techniques such as X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy, we employed unconventional approaches, specifically solid- and liquid-state high-resolution nuclear magnetic resonance (NMR) spectroscopy, supplemented by gel permeation chromatography (GPC). Scanning electron microscopy (SEM) was also used to examine changes in the size of the NPs after contact with solvents and after heating. Our investigations revealed suspected strong binding and networking of the NPs, and a soluble monomer/oligomer phase was identified and characterised. This fraction is removable using solvent or heat treatment without significantly affecting the size of the NPs. Additionally, we suggested the chemical structure of this soluble phase. Our findings support the proposed rubber-like character of plasma polymer NPs and explain their strong tendency to reflect from substrates upon high-speed impact.

Changes in Pore Structure and Fractal Characteristics of Solvents Pretreated High-Rank Coal under Supercritical CO2

CO2 injection in coal seams, which is a significant initiative to mitigate environmental problems caused by greenhouse gases, often leads a sequence of changes in the physical properties of coal reservoirs. To look into how the pore structure changes in the process of CO2 sequestration, we selected fresh coal from Huoerxinhe coal mine in China as the object. Then, acid treatment and SC-CO2 extraction were used to dissolve Organic and inorganic components in coal. Thus, by using SEM, LTGA-N2 apparatus and XRD, the characteristics of pore parameter and fractal dimension variation were discussed. The research results show that, the APS of samples THF, HCL-HF and Y-C increase, while the total PV decreases and the pore connectivity deteriorates. The pore connectivity of Samples THF and HCL-HF is improved (THF-C, HCL-HF-C), but the total pore volume continuously reduces. In addition, solvents treatment and SC-CO2 extraction mainly act on the microporous fraction. After solvents pretreatment, the changes in the pore size distribution curves are mainly manifested in the reduction of number of micropores, especially in the micropores around 3–4 nm. There is a small increase in micropores for samples Y-C and HCL-HF-C, with the pore size mainly concentrated around 4 nm, while the pores of the sample THF-C mainly show an increase within the scope of 3–16 nm. Generally, solvent pretreatment and SC-CO2 extraction help to simplify pore structure. However, the sample HCL-HF-C shows opposite change characteristics. In a short period of time, the larger pore fractal dimension, the less beneficial it is to the flow of CO2, while pore fractal dimension becomes progressively less useful in assessing pore connectivity with increasing time.

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

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