The Vrentas-Duda free-volume theory has been extensively used tocorrelated or predict the solvent diffusion coefficient of apolymer/solvent system. The energy term in the free volume diffusionequation is difficult to ...The Vrentas-Duda free-volume theory has been extensively used tocorrelated or predict the solvent diffusion coefficient of apolymer/solvent system. The energy term in the free volume diffusionequation is difficult to estimate, so the energy term was usuallyneglected in previous predictive versions of the free volumediffusion coefficient equation. Recent studies show that the energyeffect is very important even above the glass transition temperatureof the system. In this paper, a new evaluating method of the energyterm is proposed, that is, the diffusion energy at different solventconcentrations is assumed to be a linear function of the solventdiffusion energy in pure solvents and that in polymers under thecondition that the solvent in infinite dilution.展开更多
The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereeva...The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.展开更多
Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics...Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics within NC-based propellants was reported,and its effect on the evolution of mechanical properties was not interpreted yet.This study is conducted to gain a comprehensive understanding of hot-air drying for NC-based propellants and clarify the effect of temperature on solvent transport behavior and further the change of mechanical properties during drying.The drying kinetic curves show the drying time required is decreased but the steady solvent content is increased and the drying rate is obviously increased with the increase of hot-air temperatures,indicating hot-air temperatures have a significant effect on drying kinetics.A modified drying model was established,and results show it is more appropriate to describe solvent transport behavior within NC-based propellants.Moreover,two linear equations were established to exhibit the relationship between solvent content and its effect on the change of tensile properties,and the decrease of residual solvent content causes an obvious increase of tensile strength and tensile modulus of propellant products,indicating its mechanical properties can be partly improved by adjustment of residual solvent content.The outcomes can be used to clarify solvent transport mechanisms and optimize drying process parameters of double-based gun propellants.展开更多
Aim To prepare the prolonged-released microspheres of mefformin hydrochloride. Methods Ion-exchange resin-drug mefformin hydrochloride complexes were prepared as core materials, and followed by coating using ethylcell...Aim To prepare the prolonged-released microspheres of mefformin hydrochloride. Methods Ion-exchange resin-drug mefformin hydrochloride complexes were prepared as core materials, and followed by coating using ethylcellulose (EC) by the emulsion solvent diffusion technique. The release rate of mefformin from the microcapsules was highly dependent on the encapsulating formulation, thus being used as an index for formulation screening. Orthogonal experiments were performed to optimize the coating formulation. Results The final chosen formulation for coating of mefformin microcapsules were as follows: ( 1 ) the ratio of EC (20cps) to EC (45cps) was 50:50; (2) the ratio of plasticizer to coating materials was 20% ;and (3) the ratio of resin-mefformin complexes to coating materials was 5 : 1. Conclusion The prolonged release microspheres of mefformin hydrochloride were successfully prepared.展开更多
The aim of this study was to prepare arsenic trioxide (ATO)-loaded stealth PEGylated PLGA nanoparticles (PEG-PLGA-NPs) and to assess the merits of PEG-PLGA-NPs as drug carriers for ATO delivery. PEG-PLGA copolymer...The aim of this study was to prepare arsenic trioxide (ATO)-loaded stealth PEGylated PLGA nanoparticles (PEG-PLGA-NPs) and to assess the merits of PEG-PLGA-NPs as drug carriers for ATO delivery. PEG-PLGA copolymer was synthesized with methoxypolyethyleneglycol (Mw=5000), D, L-lactide, and glycolide by the ring-opening polymerization method. Amorphous ATO was transformed into cubic crystal form to increase its solu-bility in the organic solvent. ATO-loaded PEG-PLGA-NPs were prepared by the modified spontaneous emulsification solvent diffusion (SESD) method, and the main experimental factors influencing the characteristics of nanopar- ticles were investigated, to optimize the preparation. To confirm the escape of PEG-PLGA-NPs from phagocytosis by phagocytes, PEG-PLGA-NPs labeled rhodamine B uptake by murine peritoneal macrophages (MPM) were analyzed by flow cytometry. The results showed that the physicochemical characteristics of PEG-PLGA-NPs were affected by the type and concentration of the emulsifiers, polymer concentration, and drug concentration. ATO-loaded PEG-PLGA-NPs, with particle size of 120.8nm, zeta potential of-10.73mV, encapsulation efficiency of 73.6%, and drug loading of 1.36%, were prepared under optimal conditions. The images of transmission electron micros-copy (TEM) indicated that the optimized nanoparticles were near spherical and without aggregation or adhesion. The release experiments in vitro showed the ATO release from PEG-PLGA-NPs exhibited consequently sustained release for more than 26d, which was in accordance with Higuchi equation. The uptake of PEG-PLGA-NPs by MPM was found to decrease markedly compared to PLGA-NPs. The experimental results showed that PEG-PLGA-NPs were potential nano drug delivery carriers for ATO.展开更多
Marangoni effect at the two-phase interface with different surface tension as a unique mass transfer phenomenon has been widely used in daily life and industrialmanufacture.However,their marvelous liquid-driving capab...Marangoni effect at the two-phase interface with different surface tension as a unique mass transfer phenomenon has been widely used in daily life and industrialmanufacture.However,their marvelous liquid-driving capability between miscible liquids has long been ignored,especially in water environments.Here,we first reveal a distinct underwater Marangoni effect between the solvent of glues and the water layer on solid surfaces.Driven by the Marangoni effect,organic solvents with water solubility,high dielectric constant,and low diffusivity could effectively exclude the interfacial water layer,enabling direct and effective contact between glues and solid surfaces.Our experimental results and theoretical simulation proved that a relatively large ratio of the Marangoni number in the horizontal direction and to the vertical direction ensured an effective underwater adhesion of the water-excluding glue.This surface engineering approach provides an alternative to the traditional methods of molecular engineering for realizing underwater adhesion.展开更多
Red-blood-cell-shaped chitosan microparticles with acid-triggered dissolution and auto-fluorescence were successfully fabricated by a simple strategy combining electrospraying with a solvent diffusion process controll...Red-blood-cell-shaped chitosan microparticles with acid-triggered dissolution and auto-fluorescence were successfully fabricated by a simple strategy combining electrospraying with a solvent diffusion process controlled by solvent evaporation. The sizes of the prepared chitosan microparticles were rela- tively uniform. Control of the solvent diffusion process was crucial for the formation of microparticles with concave morphology. A chitosan aqueous solution containing 20vo1% ethanol as the evaporable solvent and 30 vol% dimethyl sulfoxide as the diffusible solvent was optimal for preparation of chitosan microparticles with the desired red-blood-cell-like size and shape. These chitosan microparticles will be highly attractive for many biological and biomedical aoolications.展开更多
基金Supported by the National Nature Science Foundation of China (No. 20076038).
文摘The Vrentas-Duda free-volume theory has been extensively used tocorrelated or predict the solvent diffusion coefficient of apolymer/solvent system. The energy term in the free volume diffusionequation is difficult to estimate, so the energy term was usuallyneglected in previous predictive versions of the free volumediffusion coefficient equation. Recent studies show that the energyeffect is very important even above the glass transition temperatureof the system. In this paper, a new evaluating method of the energyterm is proposed, that is, the diffusion energy at different solventconcentrations is assumed to be a linear function of the solventdiffusion energy in pure solvents and that in polymers under thecondition that the solvent in infinite dilution.
基金Project ( 2001AA218011) supported by the National High Technology Development "863" Program of China
文摘The nanoparticles of polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) were prepared by the bi-nary organic solvent diffusion method. The yield, particle size and size distribution of these nanoparticles wereevaluated. The yield of nanoparticles prepared by this method is over 90%, and the average size of the nanoparticlesis between 130-180 nm. In order to clarify the effect of the organic solvent used in the system on nanoparticle yieldand size, the cloud points of PLA and PLGA were examined by cloud point titration. The results indicate that theyields of nanoparticles increase with the increase of ethanol in the acetone solution and attain the maximum at thecloud point of ethanol, while the size of nanoparticles decreases with the increase of ethanol in the acetone solutionand attains the minimum at the cloud point of ethanol. The optimal composition ratio of binary organic solvents coin-cides to that near the cloud point and the optimal condition of binary organic solvents can be predicted.
基金the National Natural Science Foundation of China(Grant No.22075146).
文摘Appropriate drying process with optimized controlling of drying parameters plays a vital role in the improvement of the quality and performance of propellant products.However,few research on solvent transport dynamics within NC-based propellants was reported,and its effect on the evolution of mechanical properties was not interpreted yet.This study is conducted to gain a comprehensive understanding of hot-air drying for NC-based propellants and clarify the effect of temperature on solvent transport behavior and further the change of mechanical properties during drying.The drying kinetic curves show the drying time required is decreased but the steady solvent content is increased and the drying rate is obviously increased with the increase of hot-air temperatures,indicating hot-air temperatures have a significant effect on drying kinetics.A modified drying model was established,and results show it is more appropriate to describe solvent transport behavior within NC-based propellants.Moreover,two linear equations were established to exhibit the relationship between solvent content and its effect on the change of tensile properties,and the decrease of residual solvent content causes an obvious increase of tensile strength and tensile modulus of propellant products,indicating its mechanical properties can be partly improved by adjustment of residual solvent content.The outcomes can be used to clarify solvent transport mechanisms and optimize drying process parameters of double-based gun propellants.
文摘Aim To prepare the prolonged-released microspheres of mefformin hydrochloride. Methods Ion-exchange resin-drug mefformin hydrochloride complexes were prepared as core materials, and followed by coating using ethylcellulose (EC) by the emulsion solvent diffusion technique. The release rate of mefformin from the microcapsules was highly dependent on the encapsulating formulation, thus being used as an index for formulation screening. Orthogonal experiments were performed to optimize the coating formulation. Results The final chosen formulation for coating of mefformin microcapsules were as follows: ( 1 ) the ratio of EC (20cps) to EC (45cps) was 50:50; (2) the ratio of plasticizer to coating materials was 20% ;and (3) the ratio of resin-mefformin complexes to coating materials was 5 : 1. Conclusion The prolonged release microspheres of mefformin hydrochloride were successfully prepared.
基金Supported by the Special Funds for Major State Basic Research Program of China (973 Program, No.2007CB935800)theNational High Technology Research and Development Program of China (863 Program, No.2004AA215162).
文摘The aim of this study was to prepare arsenic trioxide (ATO)-loaded stealth PEGylated PLGA nanoparticles (PEG-PLGA-NPs) and to assess the merits of PEG-PLGA-NPs as drug carriers for ATO delivery. PEG-PLGA copolymer was synthesized with methoxypolyethyleneglycol (Mw=5000), D, L-lactide, and glycolide by the ring-opening polymerization method. Amorphous ATO was transformed into cubic crystal form to increase its solu-bility in the organic solvent. ATO-loaded PEG-PLGA-NPs were prepared by the modified spontaneous emulsification solvent diffusion (SESD) method, and the main experimental factors influencing the characteristics of nanopar- ticles were investigated, to optimize the preparation. To confirm the escape of PEG-PLGA-NPs from phagocytosis by phagocytes, PEG-PLGA-NPs labeled rhodamine B uptake by murine peritoneal macrophages (MPM) were analyzed by flow cytometry. The results showed that the physicochemical characteristics of PEG-PLGA-NPs were affected by the type and concentration of the emulsifiers, polymer concentration, and drug concentration. ATO-loaded PEG-PLGA-NPs, with particle size of 120.8nm, zeta potential of-10.73mV, encapsulation efficiency of 73.6%, and drug loading of 1.36%, were prepared under optimal conditions. The images of transmission electron micros-copy (TEM) indicated that the optimized nanoparticles were near spherical and without aggregation or adhesion. The release experiments in vitro showed the ATO release from PEG-PLGA-NPs exhibited consequently sustained release for more than 26d, which was in accordance with Higuchi equation. The uptake of PEG-PLGA-NPs by MPM was found to decrease markedly compared to PLGA-NPs. The experimental results showed that PEG-PLGA-NPs were potential nano drug delivery carriers for ATO.
基金supported by the National Key R&D Program of China(project nos.2018YFA0209500 and 2019YFA0709300)the National Natural Science Foundation of China(grant nos.21621091,21972155,21975209,22005255,22035008,52025132,and 22205244)+2 种基金Projects of International Cooperation and Exchanges Natural Science Foundation of China(NSFC,grant no.1A1111KYSB20200010)National Program for Special Support of Eminent Professionals and the Fundamental Research Funds for Central Universities(grant no.20720190037)the China Postdoctoral Science Foundation(grant no.2022M713225).
文摘Marangoni effect at the two-phase interface with different surface tension as a unique mass transfer phenomenon has been widely used in daily life and industrialmanufacture.However,their marvelous liquid-driving capability between miscible liquids has long been ignored,especially in water environments.Here,we first reveal a distinct underwater Marangoni effect between the solvent of glues and the water layer on solid surfaces.Driven by the Marangoni effect,organic solvents with water solubility,high dielectric constant,and low diffusivity could effectively exclude the interfacial water layer,enabling direct and effective contact between glues and solid surfaces.Our experimental results and theoretical simulation proved that a relatively large ratio of the Marangoni number in the horizontal direction and to the vertical direction ensured an effective underwater adhesion of the water-excluding glue.This surface engineering approach provides an alternative to the traditional methods of molecular engineering for realizing underwater adhesion.
文摘Red-blood-cell-shaped chitosan microparticles with acid-triggered dissolution and auto-fluorescence were successfully fabricated by a simple strategy combining electrospraying with a solvent diffusion process controlled by solvent evaporation. The sizes of the prepared chitosan microparticles were rela- tively uniform. Control of the solvent diffusion process was crucial for the formation of microparticles with concave morphology. A chitosan aqueous solution containing 20vo1% ethanol as the evaporable solvent and 30 vol% dimethyl sulfoxide as the diffusible solvent was optimal for preparation of chitosan microparticles with the desired red-blood-cell-like size and shape. These chitosan microparticles will be highly attractive for many biological and biomedical aoolications.