The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to...The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to provide ideas for this issue.This strategy relied on using appropriate mechanical treatment and sodium lignosulfonate coating to improve the dispersion and interfacial compatibility of bamboo fibers in poly(lactic acid).By optimising the particle size and concentration of sodium lignosulphonate,high value-added and green composites were prepared using sectional pressurization with a venting procedure.The treated composite displayed an ultra-smooth surface(roughness of 0.592 nm),impressive transient properties(disintegration and degradation behaviour after 30 d),and outstanding ultraviolet(UV)shielding properties(100%).These properties hold the promise of being an excellent substrate for electronic devices,especially for high-precision processing,transient electronics,and UV damage prevention.The satisfactory interfacial compatibility of the composites was confirmed by detailed characterisation regarding the related physicochemical properties.This investigation offers a sustainable approach for producing high value-added green composites from biomass and biomass-derived materials.展开更多
This article provided a preparation protocol for poly(lactic acid)(PLA)/modified epoxidized soybean oil(ECP)/nano-magnesium oxide(n-MgO)ternary composites and studied their mechanical and antibacterial properties.By m...This article provided a preparation protocol for poly(lactic acid)(PLA)/modified epoxidized soybean oil(ECP)/nano-magnesium oxide(n-MgO)ternary composites and studied their mechanical and antibacterial properties.By means of an organic synthesis technique,epoxidized soybean oil(ESO)is chemically grafted to PLA to synthesize ESO chemically plastically modified PLA,abbreviated ECP.To fabricate PLA/ECP/n-MgO composite materials,ECP acts as a plasticizer and a compatibilizer simultaneously,and n-MgO acts as an enhancer.Then scanning electron microscopy,X-ray diffraction,differential scanning calorimetry,universal tester,and antibacterial research were exploited to characterize the morphology,thermal resistance,mechanical properties,and antibacterial performance of PLA/ECP/n-MgO composites.The experimental results show that ECP acts as a plasticizer by causing heterogeneous nucleation,which increases PLA's crystallinity.Evenly distributed n-MgO can greatly improve PLA's antibacterial qualities.Furthermore,ECP and n-MgO work together to improve the positive aspects of PLA/ECP/n-MgO composites,with PLA/ECP/n-MgO 100/1/0.5 composites having the best overall properties.While improving the mechanical performance and toughness of PLA,this work offers a prospective approach and foundational database for the creation of multifunctional biodegradable composites.展开更多
To retain its inherent biodegradability,simultaneously improving the strength and toughness of poly(lactic acid)(PLA)is a significant challenge.In this study,we propose an innovative multiple dynamic pressure(MDP)proc...To retain its inherent biodegradability,simultaneously improving the strength and toughness of poly(lactic acid)(PLA)is a significant challenge.In this study,we propose an innovative multiple dynamic pressure(MDP)process that can produce pure PLA with excellent mechanical properties.The MDP process generates a dynamic stretching effect by regulating the application and release of pressure,prompting disordered molecular chains to be arranged regularly along the direction of the dynamic force field.This promoted the formation of more ordered crystal forms(α-form)and strengthened the connection between the crystalline and amorphous regions.Results show that after MDP treatment,the tensile strength and strain at break of MDP-PLA are significantly improved,reaching 91.6 MPa and 80.1%respectively,which are 49.4%higher and 10 times higher than those of the samples before treatment.The mechanical properties of MDP-PLA can be regulated as needed by adjusting the cycle times and peak pressure.In addition,through a systematic study of the structural evolution of MDP-PLA,the performance regulation mechanism of the MDP process was thoroughly investigated,and the internal relationship among the process-structure-performance was clarified.This research not only opens a new technical path for the preparation of high-performance pure PLA but also provides important guidance for the high-performance modification of other semi-crystalline polymers,thus possessing significant scientific and engineering value.展开更多
Poly(lactic acid)(PLA),a bio-based polymer,is considered to be a sustainable alternative to conventional petroleum-based plastics.However,owing to its widespread use and relatively slow degradation rate in water,PLA s...Poly(lactic acid)(PLA),a bio-based polymer,is considered to be a sustainable alternative to conventional petroleum-based plastics.However,owing to its widespread use and relatively slow degradation rate in water,PLA still poses potential environmental pollution risks after being discarded.The efficient chemical recycling of PLA represents an attractive approach to addressing both resource reuse and environmental pollution challenges caused by its waste.Hydrolysis is the predominant method of industrial recycling.However,because PLA is insoluble in water,efficient heterogeneous hydrolysis requires high-temperature and high-pressure conditions.In this study,an efficient homogenous hydrolysis method capable of simultaneously dissolving PLA and calcium hydroxide(Ca(OH)_(2))was developed.Suitable solvents for this method were screened,and it was found that PLA hydrolysis using dioxane and 1,4,7,10,13-Pen-taoxacyclopentadecane as solvents achieved conversion rates of 93%and 90%,respectively,within 2 h at room temperature.Notably,the hydrolysis product,calcium lactate,precipitated as a solid from the solvent and therefore self-separated from the reaction solution.The solvent,acid/base conditions,water content,and depolymerization kinetics were investigated.Compared with previously reported hydrolysis methods,the enhanced efficiency observed in this study can be attributed to the concurrent solvation of PLA and Ca(OH)_(2),which maintains homogeneity throughout the reaction process.Additionally,this method facilitates closed-loop recycling of PLA and is compatible with the highly selective recovery of PLA from various types of PLA products.展开更多
AIM:To develop a 5-fluorouracil(5-FU)mesoporous poly(lactic)acid(PLA)delivery system for glaucoma filtration surgery suitable for a single subconjunctival implantation.METHODS:The 5-FU was infiltration-loaded into mes...AIM:To develop a 5-fluorouracil(5-FU)mesoporous poly(lactic)acid(PLA)delivery system for glaucoma filtration surgery suitable for a single subconjunctival implantation.METHODS:The 5-FU was infiltration-loaded into mesoporous PLA.In vitro and in vivo release experiments and ocular toxicology evaluation of the formulation were performed.The antiproliferative effect of this 5-FU-PLA tablet after glaucoma filtration surgery in rabbits was evaluated.Pathology,immunohistochemistry,and Western blot were used to further validate the inhibitory effect of this sustained release system.RESULTS:Various drug formulations were tested,and two 5-FU-PLA tablets,namely 1.5P15(5-FU 1.5 mg+PLA 15000 Da)and 2.5P15(5-FU 2.5 mg+PLA 15000 Da),had the most suitable release profiles in vitro.Further in vivo studies confirmed the safety and sustained-release profiles of both drugs.Both 5-FU-PLA tablets,relative to the free drugs,significantly inhibited tissue proliferation after glaucoma filtration and improved surgical success.Western blot showed that transforming growth factor-β(TGF-β)and connective tissue growth factor(CTGF)were inhibited by 5-FU after filtration surgery,with the effects of the 5-FU-PLA tablets being more lasting.CONCLUSION:The tested 5-FU-PLA tablets provide a sustained release of 5-FU,which may be used for a single subconjunctival implantation to inhibit proliferation after filtration surgery.展开更多
The continuous improvement in patient care and recovery is driving the development of innovative materials for medical applications.Medical sutures,essential for securing implants and closing deep wounds,have evolved ...The continuous improvement in patient care and recovery is driving the development of innovative materials for medical applications.Medical sutures,essential for securing implants and closing deep wounds,have evolved to incorporate smart materials capable of responding to various stimuli.This study explores the potential of thermoresponsive sutures,made from shape memory materials,that contract upon heating to bring loose stitches closer together,promoting optimal wound closure.We developed nanocomposites based on a blend of poly(lactic acid)(PLA)and thermoplastic polyurethane(TPU)—biopolymers that inherently exhibit shape memory—enhanced with carbon nanotubes(CNT)and graphene nanoplatelets(GN)to improve mechanical performance.PLA/TPU(50/50)nanocomposites were prepared with 1 and 2 wt%GN,as well as hybrid formulations combining 1 wt%CNT with 1 or 2 wt%GN,using a twin-screw extrusion process to form filaments.These filaments were characterized through differential scanning calorimetry(DSC),field emission gun scanning electron microscopy(FEG-SEM),tensile testing,and shape memory assessments.While the PLA/TPU blend is immiscible,TPU enhances the crystallinity(X_(c))of the PLA phase,further increased by the addition of CNT and GN.FEG-SEM images indicate CNTs primarily in the PLA phase and GN in the TPU phase.PLA/TPU with 1 or 2 wt%GN showed the highest potential for suture applications,with a high elastic modulus(~1000 MPa),significant strain at break(~10%),and effective shape recovery(~20%at 55℃ for 30 min).These findings suggest that these nanocomposites can enhance suture performance with controlled shape recovery that is suitable for medical use.展开更多
For a polymer/polymer dismissible blend with two crystallizable components,the crystallization behavior of different components and the reciprocal influences between different crystals are interesting and important,bu...For a polymer/polymer dismissible blend with two crystallizable components,the crystallization behavior of different components and the reciprocal influences between different crystals are interesting and important,but did not investigate in detail.In this study,the L-poly(lactic acid)/polypropylene(PLLA/PP)blends with different weight ratios were prepared by melt mixing and the crystallization behavior of the blends were investigated.Results showed that the crystalline structures of PLLA and PP were not altered by the composition.For the crystallization of PLLA,both the diffusion of chain segments and crystallization rate were enhanced under the existence of PP crystals.For the crystallization of PP,its crystallization rate was depressed under the existence of amorphous PLLA molecular chains.When the PP crystallized from the existence of PLLA crystals,although the diffusion rate of PP was reduced by PLLA crystals,the nucleation positions were obviously enhanced,which accelerated the formation of PP crystals.This investigation would supply more basic data for the application of PLLA/PP blend.展开更多
The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts ...The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts for lactic acid oxidation reaction(LAOR)and understanding the reaction process are challenging.Here,we report the electrooxidation of waste PLA to acetate at a high current density of 100 mA cm-2 with high Faraday efficiency(~95%)and excellent stability(>100 h)over a nickel selenide nanosheet catalyst.In addition,a total Faraday efficiency of up to 190%was achieved for carboxylic acids,including acetic acid and formic acid,by coupling with the cathodic CO_(2) reduction reaction.In situ experimental results and theoretical simulations revealed that the catalytic activity center of LAOR was dynamically formed NiOOH species,and the surface-adsorbed SeO_(x) species accelerated the formation of Ni~(3+)species,thus promoting catalytic activity.The mechanism of lactic acid electrooxidation was further elucidated.Lactic acid was dehydrogenated to produce pyruvate first and then formed CH_3CO due to preferential C-C bond cleavage,resulting in the presence of acetate.This work demonstrated a sustainable method for recycling waste PLA and CO_(2) into high-value-added products.展开更多
Star-shaped poly(lactic acid)s(PLAs)with two to five arms were synthesized by ring opening polymerization using tin(II)2-ethylhexanoate as catalyst and polyols as initiators.The effects of molecular weight together wi...Star-shaped poly(lactic acid)s(PLAs)with two to five arms were synthesized by ring opening polymerization using tin(II)2-ethylhexanoate as catalyst and polyols as initiators.The effects of molecular weight together with multi-arm architecture on crystallization behavior,spherulite morphology and alkaline degradation behavior of star-shaped PLAs have been investigated.The results indicate that the multi-arm architecture interfered with spherulite growth,but promoted nucleation and alkaline degradation of star-shaped PLAs.Interestingly,with the increase of molecular weight(M_(n)),the crystallization rate first increased and then decreased,while the alkaline degradation rate was the opposite.The characteristic crystallization and alkaline degradation behavior of star-shaped PLAs were discussed based on the competition between segmental mobility and central core confinement.展开更多
The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA v...The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA via the solvent casting technique,the water vapor barrier property of the PLA/OC/ZnOfilm improved by a maximum of 86%compared to the neat PLAfilm without the deterioration of Young’s modulus or the tensile strength.Moreover,thefilm’s self-antibacterial activity against foodborne pathogens,including gram-negative(Escherichia coli,E.coli)and gram-positive(Staphylococcus aureus,S.aureus)bacteria,was enhanced by a max-imum of approximately 98–99%compared to the neat PLAfilm.Furthermore,SEM images revealed the homo-geneous dispersion of both nano-fillers in the PLA matrix.However,the thermal stability of thefilm decreased slightly after the addition of the OC and ZnO.Thefilm exhibited notable light barrier properties in the UV-Vis range.Moreover,the incorporation of a suitable biodegradable plasticizer significantly decreased the Tg and notably enhanced theflexibility of the nanocompositefilm by increasing the elongation at break approxi-mately 1.5-fold compared to that of the neat PLAfilm.This contributes to its feasibility as an active food packa-ging material.展开更多
基金supported by the National Natural Science Foundation of China(Nos.31971741 and 31760195)the Yunnan Fundamental Research Projects(Nos.2018FB066 and 202001AT070141)the Yunnan Agricultural Basic Research Special Projects(No.202101BD070001-086).
文摘The increasing deployment of electronics in everyday life has generated great concerns regarding the effective disposal of waste from these components.Here,we focused on a facile sustainable and economical strategy to provide ideas for this issue.This strategy relied on using appropriate mechanical treatment and sodium lignosulfonate coating to improve the dispersion and interfacial compatibility of bamboo fibers in poly(lactic acid).By optimising the particle size and concentration of sodium lignosulphonate,high value-added and green composites were prepared using sectional pressurization with a venting procedure.The treated composite displayed an ultra-smooth surface(roughness of 0.592 nm),impressive transient properties(disintegration and degradation behaviour after 30 d),and outstanding ultraviolet(UV)shielding properties(100%).These properties hold the promise of being an excellent substrate for electronic devices,especially for high-precision processing,transient electronics,and UV damage prevention.The satisfactory interfacial compatibility of the composites was confirmed by detailed characterisation regarding the related physicochemical properties.This investigation offers a sustainable approach for producing high value-added green composites from biomass and biomass-derived materials.
基金Funded by the National Natural Science Foundation of China(No.21104031)the Education Department of Hunan province in 2020(No.20C1589)。
文摘This article provided a preparation protocol for poly(lactic acid)(PLA)/modified epoxidized soybean oil(ECP)/nano-magnesium oxide(n-MgO)ternary composites and studied their mechanical and antibacterial properties.By means of an organic synthesis technique,epoxidized soybean oil(ESO)is chemically grafted to PLA to synthesize ESO chemically plastically modified PLA,abbreviated ECP.To fabricate PLA/ECP/n-MgO composite materials,ECP acts as a plasticizer and a compatibilizer simultaneously,and n-MgO acts as an enhancer.Then scanning electron microscopy,X-ray diffraction,differential scanning calorimetry,universal tester,and antibacterial research were exploited to characterize the morphology,thermal resistance,mechanical properties,and antibacterial performance of PLA/ECP/n-MgO composites.The experimental results show that ECP acts as a plasticizer by causing heterogeneous nucleation,which increases PLA's crystallinity.Evenly distributed n-MgO can greatly improve PLA's antibacterial qualities.Furthermore,ECP and n-MgO work together to improve the positive aspects of PLA/ECP/n-MgO composites,with PLA/ECP/n-MgO 100/1/0.5 composites having the best overall properties.While improving the mechanical performance and toughness of PLA,this work offers a prospective approach and foundational database for the creation of multifunctional biodegradable composites.
基金supported by the National Key Research and Development Program of China(No.2023YFC3904604)the Fundamental Research Funds for the Central Universities(No.2024ZYGXZR080)+1 种基金Science and Technology Project of Guangzhou(No.2025A04J3914)Research and Development Program of Jiangmen(No.2023780200030009506).
文摘To retain its inherent biodegradability,simultaneously improving the strength and toughness of poly(lactic acid)(PLA)is a significant challenge.In this study,we propose an innovative multiple dynamic pressure(MDP)process that can produce pure PLA with excellent mechanical properties.The MDP process generates a dynamic stretching effect by regulating the application and release of pressure,prompting disordered molecular chains to be arranged regularly along the direction of the dynamic force field.This promoted the formation of more ordered crystal forms(α-form)and strengthened the connection between the crystalline and amorphous regions.Results show that after MDP treatment,the tensile strength and strain at break of MDP-PLA are significantly improved,reaching 91.6 MPa and 80.1%respectively,which are 49.4%higher and 10 times higher than those of the samples before treatment.The mechanical properties of MDP-PLA can be regulated as needed by adjusting the cycle times and peak pressure.In addition,through a systematic study of the structural evolution of MDP-PLA,the performance regulation mechanism of the MDP process was thoroughly investigated,and the internal relationship among the process-structure-performance was clarified.This research not only opens a new technical path for the preparation of high-performance pure PLA but also provides important guidance for the high-performance modification of other semi-crystalline polymers,thus possessing significant scientific and engineering value.
基金financially supported by the National Key R&D Program of China(No.2021YFB3801901)the National Natural Science Foundation of China(No.22075188 and U19A2095)supported by State Key Laboratory of Materials Processing and Die&Mould Technology,Huazhong University of Science and Technology。
文摘Poly(lactic acid)(PLA),a bio-based polymer,is considered to be a sustainable alternative to conventional petroleum-based plastics.However,owing to its widespread use and relatively slow degradation rate in water,PLA still poses potential environmental pollution risks after being discarded.The efficient chemical recycling of PLA represents an attractive approach to addressing both resource reuse and environmental pollution challenges caused by its waste.Hydrolysis is the predominant method of industrial recycling.However,because PLA is insoluble in water,efficient heterogeneous hydrolysis requires high-temperature and high-pressure conditions.In this study,an efficient homogenous hydrolysis method capable of simultaneously dissolving PLA and calcium hydroxide(Ca(OH)_(2))was developed.Suitable solvents for this method were screened,and it was found that PLA hydrolysis using dioxane and 1,4,7,10,13-Pen-taoxacyclopentadecane as solvents achieved conversion rates of 93%and 90%,respectively,within 2 h at room temperature.Notably,the hydrolysis product,calcium lactate,precipitated as a solid from the solvent and therefore self-separated from the reaction solution.The solvent,acid/base conditions,water content,and depolymerization kinetics were investigated.Compared with previously reported hydrolysis methods,the enhanced efficiency observed in this study can be attributed to the concurrent solvation of PLA and Ca(OH)_(2),which maintains homogeneity throughout the reaction process.Additionally,this method facilitates closed-loop recycling of PLA and is compatible with the highly selective recovery of PLA from various types of PLA products.
基金Supported by the National Natural Science Foundation of China(No.82301211)Beijing Natural Science Foundation(No.J230028).
文摘AIM:To develop a 5-fluorouracil(5-FU)mesoporous poly(lactic)acid(PLA)delivery system for glaucoma filtration surgery suitable for a single subconjunctival implantation.METHODS:The 5-FU was infiltration-loaded into mesoporous PLA.In vitro and in vivo release experiments and ocular toxicology evaluation of the formulation were performed.The antiproliferative effect of this 5-FU-PLA tablet after glaucoma filtration surgery in rabbits was evaluated.Pathology,immunohistochemistry,and Western blot were used to further validate the inhibitory effect of this sustained release system.RESULTS:Various drug formulations were tested,and two 5-FU-PLA tablets,namely 1.5P15(5-FU 1.5 mg+PLA 15000 Da)and 2.5P15(5-FU 2.5 mg+PLA 15000 Da),had the most suitable release profiles in vitro.Further in vivo studies confirmed the safety and sustained-release profiles of both drugs.Both 5-FU-PLA tablets,relative to the free drugs,significantly inhibited tissue proliferation after glaucoma filtration and improved surgical success.Western blot showed that transforming growth factor-β(TGF-β)and connective tissue growth factor(CTGF)were inhibited by 5-FU after filtration surgery,with the effects of the 5-FU-PLA tablets being more lasting.CONCLUSION:The tested 5-FU-PLA tablets provide a sustained release of 5-FU,which may be used for a single subconjunctival implantation to inhibit proliferation after filtration surgery.
基金This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoalde Nível Superior-Brasil(CAPES)-Finance Code 001.
文摘The continuous improvement in patient care and recovery is driving the development of innovative materials for medical applications.Medical sutures,essential for securing implants and closing deep wounds,have evolved to incorporate smart materials capable of responding to various stimuli.This study explores the potential of thermoresponsive sutures,made from shape memory materials,that contract upon heating to bring loose stitches closer together,promoting optimal wound closure.We developed nanocomposites based on a blend of poly(lactic acid)(PLA)and thermoplastic polyurethane(TPU)—biopolymers that inherently exhibit shape memory—enhanced with carbon nanotubes(CNT)and graphene nanoplatelets(GN)to improve mechanical performance.PLA/TPU(50/50)nanocomposites were prepared with 1 and 2 wt%GN,as well as hybrid formulations combining 1 wt%CNT with 1 or 2 wt%GN,using a twin-screw extrusion process to form filaments.These filaments were characterized through differential scanning calorimetry(DSC),field emission gun scanning electron microscopy(FEG-SEM),tensile testing,and shape memory assessments.While the PLA/TPU blend is immiscible,TPU enhances the crystallinity(X_(c))of the PLA phase,further increased by the addition of CNT and GN.FEG-SEM images indicate CNTs primarily in the PLA phase and GN in the TPU phase.PLA/TPU with 1 or 2 wt%GN showed the highest potential for suture applications,with a high elastic modulus(~1000 MPa),significant strain at break(~10%),and effective shape recovery(~20%at 55℃ for 30 min).These findings suggest that these nanocomposites can enhance suture performance with controlled shape recovery that is suitable for medical use.
基金supported by the National Natural Science Foundation of China(Nos.51403089 and 21574060)the Major Special Projects of Jiangxi Provincial Department of Science and Technology(No.20114ABF05100)+3 种基金the Project of Jiangxi Provincial Department of Education(No.GJJ170229)the China Postdoctoral Science Foundation(No.2019M652282)the Postdoctoral Science Foundation of Jiangxi Province(No.2018KY37)the Technology Plan Landing Project of Jiangxi Provincial Department of Education(No.GCJ2011-243).
文摘For a polymer/polymer dismissible blend with two crystallizable components,the crystallization behavior of different components and the reciprocal influences between different crystals are interesting and important,but did not investigate in detail.In this study,the L-poly(lactic acid)/polypropylene(PLLA/PP)blends with different weight ratios were prepared by melt mixing and the crystallization behavior of the blends were investigated.Results showed that the crystalline structures of PLLA and PP were not altered by the composition.For the crystallization of PLLA,both the diffusion of chain segments and crystallization rate were enhanced under the existence of PP crystals.For the crystallization of PP,its crystallization rate was depressed under the existence of amorphous PLLA molecular chains.When the PP crystallized from the existence of PLLA crystals,although the diffusion rate of PP was reduced by PLLA crystals,the nucleation positions were obviously enhanced,which accelerated the formation of PP crystals.This investigation would supply more basic data for the application of PLLA/PP blend.
基金financially supported by the National Key R&D Program of China (2021YFA1501700)the National Science Foundation of China (22272114)+4 种基金the Fundamental Research Funds from Sichuan University (2022SCUNL103)the Funding for Hundred Talent Program of Sichuan University (20822041E4079)the NSFC (22102018 and 52171201)the Huzhou Science and Technology Bureau (2022GZ45)the Hefei National Research Center for Physical Sciences at the Microscale (KF2021005)。
文摘The conversion of waste polylactic acid(PLA)plastics into high-value-added chemicals through electrochemical methods is a promising and sustainable approach.However,developing efficient and highly selective catalysts for lactic acid oxidation reaction(LAOR)and understanding the reaction process are challenging.Here,we report the electrooxidation of waste PLA to acetate at a high current density of 100 mA cm-2 with high Faraday efficiency(~95%)and excellent stability(>100 h)over a nickel selenide nanosheet catalyst.In addition,a total Faraday efficiency of up to 190%was achieved for carboxylic acids,including acetic acid and formic acid,by coupling with the cathodic CO_(2) reduction reaction.In situ experimental results and theoretical simulations revealed that the catalytic activity center of LAOR was dynamically formed NiOOH species,and the surface-adsorbed SeO_(x) species accelerated the formation of Ni~(3+)species,thus promoting catalytic activity.The mechanism of lactic acid electrooxidation was further elucidated.Lactic acid was dehydrogenated to produce pyruvate first and then formed CH_3CO due to preferential C-C bond cleavage,resulting in the presence of acetate.This work demonstrated a sustainable method for recycling waste PLA and CO_(2) into high-value-added products.
基金This work was financially supported by the National Natural Science Foundation of China(No.51973010).
文摘Star-shaped poly(lactic acid)s(PLAs)with two to five arms were synthesized by ring opening polymerization using tin(II)2-ethylhexanoate as catalyst and polyols as initiators.The effects of molecular weight together with multi-arm architecture on crystallization behavior,spherulite morphology and alkaline degradation behavior of star-shaped PLAs have been investigated.The results indicate that the multi-arm architecture interfered with spherulite growth,but promoted nucleation and alkaline degradation of star-shaped PLAs.Interestingly,with the increase of molecular weight(M_(n)),the crystallization rate first increased and then decreased,while the alkaline degradation rate was the opposite.The characteristic crystallization and alkaline degradation behavior of star-shaped PLAs were discussed based on the competition between segmental mobility and central core confinement.
基金Prince of Songkla University(PSU),Hat Yai,Songkhla,Thailand(Grant Number AGR581246S).
文摘The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA via the solvent casting technique,the water vapor barrier property of the PLA/OC/ZnOfilm improved by a maximum of 86%compared to the neat PLAfilm without the deterioration of Young’s modulus or the tensile strength.Moreover,thefilm’s self-antibacterial activity against foodborne pathogens,including gram-negative(Escherichia coli,E.coli)and gram-positive(Staphylococcus aureus,S.aureus)bacteria,was enhanced by a max-imum of approximately 98–99%compared to the neat PLAfilm.Furthermore,SEM images revealed the homo-geneous dispersion of both nano-fillers in the PLA matrix.However,the thermal stability of thefilm decreased slightly after the addition of the OC and ZnO.Thefilm exhibited notable light barrier properties in the UV-Vis range.Moreover,the incorporation of a suitable biodegradable plasticizer significantly decreased the Tg and notably enhanced theflexibility of the nanocompositefilm by increasing the elongation at break approxi-mately 1.5-fold compared to that of the neat PLAfilm.This contributes to its feasibility as an active food packa-ging material.
