Pub Date : 2024-09-29DOI: 10.1016/j.supflu.2024.106417
Praziquantel (PZQ) is an anthelmintic drug with low solubility, therefore cocrystallization and particle size reduction is desirable to improve bioavailability. In this study, a PZQ-malonic acid cocrystal was micronized by rapid expansion of supercritical solution (RESS). Due to low solubility in scCO2, four cosolvents were screened as RESS modifiers. While addition of acetone or THF yielded mixtures of PZQ and its cocrystal, MeOH and EtOH produced pure cocrystal. Impact of pressure (15–30 MPa), temperature (35–55 °C), and cosolvent loading (3–10 volumes) on phase-purity, yield, and particle size were investigated. Adding cosolvent to RESS facilitated dissolution of cocrystal formers in scCO2 and crystallization of the cocrystal with yields up to 68.5 wt% and particle size as low as 600 nm. Results show that for APIs with low solubility in scCO2, cosolvent-modified RESS is a suitable approach for simultaneous crystallization and micronization.
{"title":"Influence of solvent selection and RESS processing conditions on formation of a praziquantel-malonic acid cocrystal in supercritical CO2","authors":"","doi":"10.1016/j.supflu.2024.106417","DOIUrl":"10.1016/j.supflu.2024.106417","url":null,"abstract":"<div><div>Praziquantel (PZQ) is an anthelmintic drug with low solubility, therefore cocrystallization and particle size reduction is desirable to improve bioavailability. In this study, a PZQ-malonic acid cocrystal was micronized by rapid expansion of supercritical solution (RESS). Due to low solubility in scCO<sub>2</sub>, four cosolvents were screened as RESS modifiers. While addition of acetone or THF yielded mixtures of PZQ and its cocrystal, MeOH and EtOH produced pure cocrystal. Impact of pressure (15–30 MPa), temperature (35–55 °C), and cosolvent loading (3–10 volumes) on phase-purity, yield, and particle size were investigated. Adding cosolvent to RESS facilitated dissolution of cocrystal formers in scCO<sub>2</sub> and crystallization of the cocrystal with yields up to 68.5 wt% and particle size as low as 600 nm. Results show that for APIs with low solubility in scCO<sub>2</sub>, cosolvent-modified RESS is a suitable approach for simultaneous crystallization and micronization.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424623","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-24DOI: 10.1016/j.supflu.2024.106416
This study aimed to develop an efficient method for converting residual biomass into biofuel through a process that combines supercritical fluid extraction and hydrothermal liquefaction. The study analyzed the compositional changes in the biomass residues using various co-solvents and assessed their potential for biofuel production. After hydrothermal liquefaction, the liquid biofuel produced showed a decrease in the H to C ratio from 1.7 to 1.6 and a reduction in the O to C ratio from 0.5 to 0.2, compared to the unprocessed feedstock, indicating a favorable alteration in elemental composition for biofuel production. Notably, residues extracted with supercritical CO2 and ethanol had the lowest yield, while those extracted with CO2 and water achieved the highest energy recovery at 101.5 %. These findings suggest that integrating supercritical fluid extraction with hydrothermal liquefaction is an environmentally sustainable and efficient approach, significantly advancing the development of sustainable biofuels.
本研究旨在通过超临界流体萃取和热液液化相结合的工艺，开发一种将残留生物质转化为生物燃料的高效方法。研究分析了使用各种助溶剂的生物质残留物的成分变化，并评估了其生产生物燃料的潜力。与未经加工的原料相比，水热液化后生产出的液体生物燃料的 H C 比值从 1.7 降至 1.6，O C 比值从 0.5 降至 0.2，这表明元素组成的改变有利于生物燃料的生产。值得注意的是，用超临界二氧化碳和乙醇萃取的残渣产量最低，而用二氧化碳和水萃取的残渣能量回收率最高，达到 101.5%。这些研究结果表明，将超临界流体萃取与水热液化相结合是一种环境可持续的高效方法，可极大地推动可持续生物燃料的发展。
{"title":"Utilizing cocoa bean husk residues from supercritical extraction for biofuel production through hydrothermal liquefaction","authors":"","doi":"10.1016/j.supflu.2024.106416","DOIUrl":"10.1016/j.supflu.2024.106416","url":null,"abstract":"<div><div>This study aimed to develop an efficient method for converting residual biomass into biofuel through a process that combines supercritical fluid extraction and hydrothermal liquefaction. The study analyzed the compositional changes in the biomass residues using various co-solvents and assessed their potential for biofuel production. After hydrothermal liquefaction, the liquid biofuel produced showed a decrease in the H to C ratio from 1.7 to 1.6 and a reduction in the O to C ratio from 0.5 to 0.2, compared to the unprocessed feedstock, indicating a favorable alteration in elemental composition for biofuel production. Notably, residues extracted with supercritical CO<sub>2</sub> and ethanol had the lowest yield, while those extracted with CO<sub>2</sub> and water achieved the highest energy recovery at 101.5 %. These findings suggest that integrating supercritical fluid extraction with hydrothermal liquefaction is an environmentally sustainable and efficient approach, significantly advancing the development of sustainable biofuels.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142424624","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-23DOI: 10.1016/j.supflu.2024.106415
The development of sustainable and efficient methods to prepare slippery lubricant-infused porous surface (SLIPS) is a profound work. In this study, using bilayer polymers restricting foaming mutually, bimodal cells were prepared through bilayer poly(methyl methacrylate) (PMMA). At the same time, uniform cells were prepared by bilayer PMMA /thermoplastic polyurethane (TPU). The prepared porous surfaces exhibited a high porosity (57 % or more). TPU as dispersed phase increased the cell density of the PMMA/TPU surface with a maximum cell density of 5.5 × 107 cells/cm2 and an average cell size of 1.0 μm. SLIPS prepared on PMMA/TPU surface with high porosity and uniform microcellular had better stability, and the sliding angle (SA) remained less than 10° after centrifugal rotation at 8000 r/min. Therefore, this work provides an approach to improve the surface cell density and produce SLIPS sustainably and efficiently.
{"title":"Fabrication of stable slippery lubricant-infused porous surface on polymethyl methacrylate/thermoplastic polyurethane by supercritical CO2 foaming","authors":"","doi":"10.1016/j.supflu.2024.106415","DOIUrl":"10.1016/j.supflu.2024.106415","url":null,"abstract":"<div><div>The development of sustainable and efficient methods to prepare slippery lubricant-infused porous surface (SLIPS) is a profound work. In this study, using bilayer polymers restricting foaming mutually, bimodal cells were prepared through bilayer poly(methyl methacrylate) (PMMA). At the same time, uniform cells were prepared by bilayer PMMA /thermoplastic polyurethane (TPU). The prepared porous surfaces exhibited a high porosity (57 % or more). TPU as dispersed phase increased the cell density of the PMMA/TPU surface with a maximum cell density of 5.5 × 10<sup>7</sup> cells/cm<sup>2</sup> and an average cell size of 1.0 μm. SLIPS prepared on PMMA/TPU surface with high porosity and uniform microcellular had better stability, and the sliding angle (<em>SA</em>) remained less than 10° after centrifugal rotation at 8000 r/min. Therefore, this work provides an approach to improve the surface cell density and produce SLIPS sustainably and efficiently.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142325952","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-19DOI: 10.1016/j.supflu.2024.106411
Oils extracted from natural plants are valuable resources because of their diverse biocidal activity against microorganisms. This paper reports, for the first time, supercritical CO2 extraction of oil from Korarima (Aframomum corrorima) seeds and its antibacterial activity evaluation. The influences of pressure, temperature, and extraction time on the yield of supercritical CO2-extracted oil (scCO2-extracted oil) were optimized using the Response Surface Methodology. Under the optimal extraction conditions of 46 °C, 15.5 MPa, and 147 min, the extraction yield reached 1.60±0.04 %, consistent with the theoretical value of 1.58 %. The compositions of the scCO2-extracted oil were identified by GC-MS, primarily consisting of nerolidol (33.97–41.20 %), geraniol (23.08–24.50 %), and α-terpinene (8.90–9.06 %). The oil exhibited significant antibacterial activity against Staphylococcus. aureus with a minimum inhibitory concentration of 1 mg·mL−1. This study highlights the potential applications of supercritical CO2 extraction technology for extracting Korarima seed oil and its use as an antibacterial ingredient in cosmetics and pharmaceuticals.
{"title":"Response surface optimization for supercritical carbon dioxide extraction of Korarima (Aframomum corrorima) seed oil and its antibacterial activity evaluation","authors":"","doi":"10.1016/j.supflu.2024.106411","DOIUrl":"10.1016/j.supflu.2024.106411","url":null,"abstract":"<div><div>Oils extracted from natural plants are valuable resources because of their diverse biocidal activity against microorganisms. This paper reports, for the first time, supercritical CO<sub>2</sub> extraction of oil from Korarima (<em>Aframomum corrorima</em>) seeds and its antibacterial activity evaluation. The influences of pressure, temperature, and extraction time on the yield of supercritical CO<sub>2</sub>-extracted oil (scCO<sub>2</sub>-extracted oil) were optimized using the Response Surface Methodology. Under the optimal extraction conditions of 46 °C, 15.5 MPa, and 147 min, the extraction yield reached 1.60±0.04 %, consistent with the theoretical value of 1.58 %. The compositions of the scCO<sub>2</sub>-extracted oil were identified by GC-MS, primarily consisting of nerolidol (33.97–41.20 %), geraniol (23.08–24.50 %), and α-terpinene (8.90–9.06 %). The oil exhibited significant antibacterial activity against <em>Staphylococcus. aureus</em> with a minimum inhibitory concentration of 1 mg·mL<sup>−1</sup>. This study highlights the potential applications of supercritical CO<sub>2</sub> extraction technology for extracting Korarima seed oil and its use as an antibacterial ingredient in cosmetics and pharmaceuticals.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0896844624002468/pdfft?md5=bd3f2f0442e2635ab13aaeb5bc35c480&pid=1-s2.0-S0896844624002468-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1016/j.supflu.2024.106407
The application of supercritical fluids as an alternative heat transfer medium in thermal processes is becoming increasingly important, whereby the understanding of their pressure drop characteristics is essential for the process and component design. With a total of 96 experiments, this publication shows a systematic analysis of the pressure drop of CO2 flow at supercritical pressures in a heated smooth pipe with an inner diameter of 4 mm, at a pressure of 7.75 MPa, mass fluxes up to 2000 kg/m2s and heat fluxes up to 235 kW/m2. The hydrostatic pressure drop accounts for between 4 % and 24 % of the total pressure drop and the pressure drop due to flow acceleration for between 12 % and 30 %, with the frictional pressure drop accounting for the largest percentage. It was found that the Filonenko correlation can predict the pipe friction pressure drop in the investigated parameter range with a mean absolute deviation of 7 %.
{"title":"Experimental investigation of the pressure drop of CO2 flow at supercritical pressures in a heated 4 mm smooth pipe with different orientations","authors":"","doi":"10.1016/j.supflu.2024.106407","DOIUrl":"10.1016/j.supflu.2024.106407","url":null,"abstract":"<div><div>The application of supercritical fluids as an alternative heat transfer medium in thermal processes is becoming increasingly important, whereby the understanding of their pressure drop characteristics is essential for the process and component design. With a total of 96 experiments, this publication shows a systematic analysis of the pressure drop of CO<sub>2</sub> flow at supercritical pressures in a heated smooth pipe with an inner diameter of 4 mm, at a pressure of 7.75 MPa, mass fluxes up to 2000 kg/m<sup>2</sup>s and heat fluxes up to 235 kW/m<sup>2</sup>. The hydrostatic pressure drop accounts for between 4 % and 24 % of the total pressure drop and the pressure drop due to flow acceleration for between 12 % and 30 %, with the frictional pressure drop accounting for the largest percentage. It was found that the Filonenko correlation can predict the pipe friction pressure drop in the investigated parameter range with a mean absolute deviation of 7 %.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-18DOI: 10.1016/j.supflu.2024.106414
Cellulose aerogels are interesting platforms for biomedical and drug delivery applications, due to their biocompatibility, biodegradability, water absorption capacity, and good textural properties. Supercritical CO2 drying has been proven as an efficient technology for obtaining aerogels and preserving the porous structure. In this work, the effect of relevant process variables (CO2 density, depressurization rate, and intermediate depressurization mode) and gel composition on the textural properties of cellulose aerogels is studied. Experiments are performed in batch-mode, and aerogel monoliths are characterized in terms of apparent density, porosity, specific surface area, and crystalline morphology. Water uptake in different buffer solutions is also evaluated. The use of thiourea in the gel formation leads to lower porosity. On the other hand, higher porosity and surface area are obtained when depressurization is slow and the system is only partially depressurized between drying cycles. Aerogels showed a good and fast water uptake capacity, regardless of the pH (200–500 %).
{"title":"Effect of supercritical CO2 drying variables and gel composition on the textural properties of cellulose aerogels","authors":"","doi":"10.1016/j.supflu.2024.106414","DOIUrl":"10.1016/j.supflu.2024.106414","url":null,"abstract":"<div><div>Cellulose aerogels are interesting platforms for biomedical and drug delivery applications, due to their biocompatibility, biodegradability, water absorption capacity, and good textural properties. Supercritical CO<sub>2</sub> drying has been proven as an efficient technology for obtaining aerogels and preserving the porous structure. In this work, the effect of relevant process variables (CO<sub>2</sub> density, depressurization rate, and intermediate depressurization mode) and gel composition on the textural properties of cellulose aerogels is studied. Experiments are performed in batch-mode, and aerogel monoliths are characterized in terms of apparent density, porosity, specific surface area, and crystalline morphology. Water uptake in different buffer solutions is also evaluated. The use of thiourea in the gel formation leads to lower porosity. On the other hand, higher porosity and surface area are obtained when depressurization is slow and the system is only partially depressurized between drying cycles. Aerogels showed a good and fast water uptake capacity, regardless of the pH (200–500 %).</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0896844624002493/pdfft?md5=ead4f2572c1445030d3d7097f9667018&pid=1-s2.0-S0896844624002493-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1016/j.supflu.2024.106412
Associative polymers based on acrylic acid and n-butyl methacrylate were synthesized via precipitation polymerization in pressurized carbon dioxide. Physicochemical characterization confirmed BMA incorporation and good reaction yields (>67.1 mol%). Size exclusion chromatography showed bimodal polymer molar mass distribution with distinct average molar masses. Rheological properties of aqueous polymer solutions were assessed under varying pH, ionic strength, and salt concentrations and demonstrated increased viscosity with higher n-butyl methacrylate content, attributed to hydrophobic associations. The apparent viscosity of the synthesized polymers was strongly influenced by the ionic strength of the aqueous solutions.
{"title":"Phase boundaries and copolymerization of acrylic acid + butyl methacrylate in supercritical carbon dioxide under high-pressure single-fluid initiation","authors":"","doi":"10.1016/j.supflu.2024.106412","DOIUrl":"10.1016/j.supflu.2024.106412","url":null,"abstract":"<div><div>Associative polymers based on acrylic acid and <em>n</em>-butyl methacrylate were synthesized via precipitation polymerization in pressurized carbon dioxide. Physicochemical characterization confirmed BMA incorporation and good reaction yields (>67.1 mol%). Size exclusion chromatography showed bimodal polymer molar mass distribution with distinct average molar masses. Rheological properties of aqueous polymer solutions were assessed under varying pH, ionic strength, and salt concentrations and demonstrated increased viscosity with higher <em>n</em>-butyl methacrylate content, attributed to hydrophobic associations. The apparent viscosity of the synthesized polymers was strongly influenced by the ionic strength of the aqueous solutions.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142319692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-17DOI: 10.1016/j.supflu.2024.106413
Ciprofloxacin is a broad-spectrum antibiotic that is proposed for pulmonary administration. In this work micronization of ciprofloxacin was performed by the Supercritical Antisolvent Technique (SAS) using ciprofloxacin base (CIP) in ethanol/acetic acid and ciprofloxacin hydrochloride salt (CIP·HCl) in methanol at 40–60 ºC and 100–150 bar. Yields ranged from 40 % to 90 %. CIP precipitated incorporating acetate whilst CIP·HCl precipitated as the AH1 anhydrous form. CIP and CIP·HCl particles exhibited an acicular morphology (0.2–0.9 μm wide × 1–4 μm long). Micronization adding lactose, PVP K-10 and K-30 modified the precipitate morphology. CIP·HCl:lactose and CIP·HCl:PVP K-30 at a 4:1 drug:excipient mass ratio precipitated like flakes. CIP·HCl:PVP K-10 precipitated as submicron globular particles suitable for oral formulation. Increasing the PVP content, the morphology changed to sheets and flakes, which could be used for pulmonary administration. The antibacterial activity of the samples for Staphylococcus epidermidis was confirmed.
{"title":"Micronization of ciprofloxacin by the Supercritical Antisolvent (SAS) Technique","authors":"","doi":"10.1016/j.supflu.2024.106413","DOIUrl":"10.1016/j.supflu.2024.106413","url":null,"abstract":"<div><div>Ciprofloxacin is a broad-spectrum antibiotic that is proposed for pulmonary administration. In this work micronization of ciprofloxacin was performed by the Supercritical Antisolvent Technique (SAS) using ciprofloxacin base (CIP) in ethanol/acetic acid and ciprofloxacin hydrochloride salt (CIP·HCl) in methanol at 40–60 ºC and 100–150 bar. Yields ranged from 40 % to 90 %. CIP precipitated incorporating acetate whilst CIP·HCl precipitated as the AH1 anhydrous form. CIP and CIP·HCl particles exhibited an acicular morphology (0.2–0.9 μm wide × 1–4 μm long). Micronization adding lactose, PVP K-10 and K-30 modified the precipitate morphology. CIP·HCl:lactose and CIP·HCl:PVP K-30 at a 4:1 drug:excipient mass ratio precipitated like flakes. CIP·HCl:PVP K-10 precipitated as submicron globular particles suitable for oral formulation. Increasing the PVP content, the morphology changed to sheets and flakes, which could be used for pulmonary administration. The antibacterial activity of the samples for <em>Staphylococcus epidermidis</em> was confirmed.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0896844624002481/pdfft?md5=13d486dd42dd5050356e46807bcdecd3&pid=1-s2.0-S0896844624002481-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310480","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1016/j.supflu.2024.106409
This work investigates the enzymatic ring-opening polymerization of poly(ω-pentadecalactone-co-globalide) using supercritical carbon dioxide as a solvent. Copolymerizations were carried out in a high-pressure variable-volume view cell to evaluate the influence of CO2:monomers mass ratios and the use of chloroform as a cosolvent. Also, Novozym® 435 and Lipura® Flex were compared as catalysts. The highest molar mass obtained with the use of a cosolvent (Mn = 24,380 g mol−1) was achieved in the 1:2:1 (CO2:monomers:chloroform) condition, reflecting the combined effect of the cosolvent and a higher concentration of the monomers, while reactions without it showed better results for molar mass (Mn up to 27,902 g mol−1). Dispersity was higher when a cosolvent was used (Dispersity up to 7.51) than reactions with supercritical carbon dioxide only (Dispersity up to 5.36). Monomer conversions above 97 % and reaction yields from 55.77 wt% up to 79.61 wt% were achieved for copolymerizations with and without a cosolvent, using Novozym® 435 as catalyst. Lipura® Flex produced copolymers with high molar mass (Mn up to 21,605 g mol−1), reaction yields up to 73 wt%, and monomer conversions from 82 % to 96 %.
{"title":"Lipase-catalyzed synthesis of poly(ω-pentadecalactone-co-globalide) in supercritical carbon dioxide","authors":"","doi":"10.1016/j.supflu.2024.106409","DOIUrl":"10.1016/j.supflu.2024.106409","url":null,"abstract":"<div><div>This work investigates the enzymatic ring-opening polymerization of poly(ω-pentadecalactone-co-globalide) using supercritical carbon dioxide as a solvent. Copolymerizations were carried out in a high-pressure variable-volume view cell to evaluate the influence of CO<sub>2</sub>:monomers mass ratios and the use of chloroform as a cosolvent. Also, Novozym® 435 and Lipura® Flex were compared as catalysts. The highest molar mass obtained with the use of a cosolvent (M<sub>n</sub> = 24,380 g mol<sup>−1</sup>) was achieved in the 1:2:1 (CO<sub>2</sub>:monomers:chloroform) condition, reflecting the combined effect of the cosolvent and a higher concentration of the monomers, while reactions without it showed better results for molar mass (M<sub>n</sub> up to 27,902 g mol<sup>−1</sup>). Dispersity was higher when a cosolvent was used (Dispersity up to 7.51) than reactions with supercritical carbon dioxide only (Dispersity up to 5.36). Monomer conversions above 97 % and reaction yields from 55.77 wt% up to 79.61 wt% were achieved for copolymerizations with and without a cosolvent, using Novozym® 435 as catalyst. Lipura® Flex produced copolymers with high molar mass (M<sub>n</sub> up to 21,605 g mol<sup>−1</sup>), reaction yields up to 73 wt%, and monomer conversions from 82 % to 96 %.</div></div>","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":null,"pages":null},"PeriodicalIF":3.4,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0896844624002444/pdfft?md5=a7e9759219941e1e1796c17e325bf48d&pid=1-s2.0-S0896844624002444-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142310913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-16DOI: 10.1016/j.supflu.2024.106410
Flexible and efficient electromagnetic interference (EMI) shielding polymer composite foams are rapidly developing, but it is difficult to avoid the deterioration of shielding properties after foaming. To solve the issue, in this work, composite foams with multivariate gradient structure of thermoplastic polyurethane (TPU) mixed with multiwalled carbon nanotubes (MWCNTs) were constructed by combining the soft-hard domains proportional gradient of TPU with filler content gradient. Gradient-structured TPU/MWCNTs foams with impedance matching layer and high reflector layer were obtained and impedance matching layer with large cells significantly reduced the density while high reflector layer with a few cells maintained relatively perfect conductive network, whose shielding efficiency was 38.2 % higher than that of unfoamed sample. Furthermore, TPU/MWCNTs composite foams presented great stability even after 1000 times bending. This special multivariate gradient structure shows potential applications in microelectronic devices and aerospace fields and is critical to the development of high-performance EMI shielding polymer foams.
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