A novel poly(d, /-lactic acid) (PDLLA) based biomimetic polymer was synthesized by grafting maleic anhydride, butanediamine and arg-gly-asp-ser (RGDS) peptides onto the backbone of PDLLA, aiming to overcome the ...A novel poly(d, /-lactic acid) (PDLLA) based biomimetic polymer was synthesized by grafting maleic anhydride, butanediamine and arg-gly-asp-ser (RGDS) peptides onto the backbone of PDLLA, aiming to overcome the acidity and auto-accelerating degradation of PDLLA during degradation and to improve its biospecificity and biocompatibility. The synthetic copolymer was characterized by FTIR, ^13C NMR and amino acid analyzer (AAA).展开更多
Inhibition of neurite growth, which is in large part mediated by the Nogo-66 receptor, affects neural regeneration following bone marrow mesenchymal stem cell transplantation. The tissue engineering scaffold poly(D,L...Inhibition of neurite growth, which is in large part mediated by the Nogo-66 receptor, affects neural regeneration following bone marrow mesenchymal stem cell transplantation. The tissue engineering scaffold poly(D,L-lactide-co-glycolic acid) has good histocompatibility and can promote the growth of regenerating nerve fibers. The present study used small interfering RNA to silence Nogo-66 receptor gene expression in bone marrow mesenchymal stem cells and Schwann cells, which were subsequently transplanted with poly(D,L-lactide-co-glycolic acid) into the spinal cord lesion regions in rats. Simultaneously, rats treated with scaffold only were taken as the control group. Hematoxylin-eosin staining and immunohistochemistry revealed that at 4 weeks after transplantation, rats had good motor function of the hind limb after treatment with Nogo-66 receptor gene-silenced ceils prus the poly(O,L-lactide-co-glycolic acid) scaffold compared with rats treated with scaffold only, and the number of bone marrow mesenchymal stem cells and neuron-like cells was also increased. At 8 weeks after transplantation, horseradish peroxidase tracing and transmission electron microscopy showed a large number of unmyelinated and myelinated nerve fibers, as well as intact regenerating axonal myelin sheath following spinal cord hemisection injury. These experimental findings indicate that transplantation of Nogo-66 receptor gene-silenced bone marrow mesenchymal stem cells and Schwann cells plus a poly(D,L-lactide-co-glycolic acid) scaffold can significantly enhance axonal regeneration of spinal cord neurons and improve motor function of the extremities in rats following spinal cord injury.展开更多
Biodegradable chitosan-g-poly (D, L-lactic acid) copolymers were prepared via two methods. (1) The lactide was grafted onto hydroxyl groups of chitosan by using macromolecular initiator sodium of trimethylsilyl-chit...Biodegradable chitosan-g-poly (D, L-lactic acid) copolymers were prepared via two methods. (1) The lactide was grafted onto hydroxyl groups of chitosan by using macromolecular initiator sodium of trimethylsilyl-chitosan, (2) poly (D,L-lactic acid)(PLA) with low molecular weight can be linked to the amino group by coupling activated PLA to trimethylsilyl-chitosan. Two graft copolymers had hydrophilic-hydrophobic character and can be applied as carriers for drug delivery.展开更多
Poly(L-lactic acid)(PLLA)is a thermoplastic material with complete degradability,high biocompatibility and excellent mechanical properties.It can replace petroleum-based polymers are currently being used in the fields...Poly(L-lactic acid)(PLLA)is a thermoplastic material with complete degradability,high biocompatibility and excellent mechanical properties.It can replace petroleum-based polymers are currently being used in the fields of packaging,agriculture,textiles,medical and so on.However,PLLA’s extremely flammability greatly limits its wider application.An bio-based flame retardant L-APP/PLLA composites was prepared by melt blending of the L-APP and PLLA.The morphology,impact properties,thermal properties and flame retardant properties of composites were investigated by field emission scanning electron microscope(SEM),impact tester,differential scanning calorimeter(DSC),thermogravimetric analyzer(TGA),limiting oxygen indexer(LOI)and horizontalvertical burning tester.The results showed that the degree of crystallization(X_(c))and LOI of L-APP/PLLA composites increased as increasing of L-APP content.What’s more,the impact strength first increased and then decreased,the glass transition temperature(T_(g))and melting temperature(T_(m))do not changed significantly.The impact strength of composites was 9.1 kJ/m^(2) at a 5 wt%loading for L-APP,which was the highest level.When the content of L-APP was 20%,the LOI was 30.8%,the Xc was 42.3%and the UL-94 level was V-0.This research can promote the value-added utilization of lignin and the application of PLLA in the fields of flame retardant materials.展开更多
In this paper, the surface structure of poly(L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with ...In this paper, the surface structure of poly(L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with carboxyl groups, sothat these functional groups could become the reactive sites for gelatin immobilization. The functional groups of the PLLAfilms were identified by ATR-FTIR spectra and XPS spectra, the changes in surface morphology were observed by usingenvironmental scanning electron microscopy (ESEM), and the hydrophilicity of modified PLLA films was examined bywater contact angle measurement. Experimental results showed that the gelatin was immobilized with water-solublecarbodiimide (EDC) onto the PLLA film's surfaces, and the gelatin content on the polymer surface was related to carboxylicgroup formed in the controlled hydrolysis process. Rough surfaces caused by hydrolysis will predominantly favor the adhesion and growth of cell; and the hydrophilicity of these surfaces after the modification procedure is enhanced.展开更多
Objective:To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid (PDLLA) rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods:P...Objective:To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid (PDLLA) rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods:PDLLA rods were emerged into PBS simultaneous body fluid with constant temperature of 37 C and the rods were embedded into muscle tissue of 20 rabbits for degradation in vitro and in vivo . The rods were taken out in 2, 4, 6. 8 and 12 weeks. Biomechanical features of bending, shearing and axial compression strength, rigidity and elastic modulus were observed during the degradation course. Statistical method was used to test the changes of biomechanical parameters. Results: (1) There was similar changes of bending, compressive, shearing strength and bending, compressive and shearing rigidity of the PDLLA rods between in vivo and in vitro. (2)Bending, compressive, shearing strength decreased 33%, 18% and 43% respectively within the first stage of the degradation, and after 6 weeks of degradation, they decreased slowly. (3)Elastic modulus, bending, compressive and shearing rigidity.decreased sharply during the 6 weeks of degradation, with a drop of 22% , 39% and 30% respectively, and after 8 weeks, they decreased slowly. Even after 12 weeks of degradation, the strength of the rods was still higher than that of sponge bone. Conclusion: During the degradation of the material, the strength and rigidity of PDLLA rods can meet the need of fracture fixation of cancellous bones.展开更多
The biocomposite films were prepared from poly(L-lactic acid)and cellulose nanocrystals.To improve interfacial compatibility of hydrophilic cellulose nanocrystals with hydrophobic matrix polymer as well as to provide ...The biocomposite films were prepared from poly(L-lactic acid)and cellulose nanocrystals.To improve interfacial compatibility of hydrophilic cellulose nanocrystals with hydrophobic matrix polymer as well as to provide the osteoconductive properties,cellulose was functionalized with poly(glutamic acid).The modified cellulose nanocrystals were better distributed and less aggregated within the matrix,which was testified by scanning electron,optical and polarized light microscopy.According to mechanical tests,composites filled with nanocrystals modified with PGlu demonstrated higher values of Young’s modulus,elongation at break and tensile strength.Incubation of composite materials in model buffer solutions for 30 weeks followed with staining of Ca^(2+)deposits with Alizarin Red S assay testified better mineralization of materials containing PGlu-modified cellulose nanocrystals as filler.As the result of in vivo experiment,the developed composite materials showed less level of inflammation in comparison with pure polymer matrix and composites filled with non-functionalized cellulose nanocrystals.展开更多
In this study, poly(L-lactic acid)/ammonium persulfate doped-polypyrrole composite fibrous scaffolds with moderate conductivity were produced by combining electrospinning with in situ polymerization. PC12 cells were...In this study, poly(L-lactic acid)/ammonium persulfate doped-polypyrrole composite fibrous scaffolds with moderate conductivity were produced by combining electrospinning with in situ polymerization. PC12 cells were cultured on these fibrous scaffolds and their growth following electrical stimulation (0-20.0 μA stimulus intensity, for 1-4 days) was observed using inverted light microscopy, and scanning electron microscopy coupled with the MTT cell viability test. The results demonstrated that the poly(L-lactic acid)/ammonium persulfate doped-polypyrrole fibrous scaffold was a dual multi-porous micro/nano fibrous scaffold. An electrical stimulation with a current intensity 5.0- 10.0 μAfor about 2 days enhanced neuronal growth and neurite outgrowth, while a high current intensity (over 15.0 μA) suppressed them. These results indicate that electrical stimulation with a moderate current intensity for an optimum time frame can promote neuronal growth and neurite outgrowth in an intensity- and time-dependent manner.展开更多
A rotating disk contactor(RDC)was designed to perform L-lactic acid fermentation with afilamentous fungi,Rhizopus oryzae,which was immobilized on the surfaces of the rotating discs.Thebioreactor was operated using r...A rotating disk contactor(RDC)was designed to perform L-lactic acid fermentation with afilamentous fungi,Rhizopus oryzae,which was immobilized on the surfaces of the rotating discs.Thebioreactor was operated using repeated-batch method as well as continuous feeding method.Ananionic resin,D354,slightly basic in nature and of high selectivity and capacity was chosen for lacticacid separation.A coupled process of L-lactic acid fermentation and ion-exchange separation wasevaluated experimentally.The results indicated that the pH value of the fermentation broth could bemaintained at about 3-3.5 without any addition of alkali.The conversion ratio of glucose to L-lacticacid was about 0.7 g·g<sup>-1</sup> and the fermentation rate reached as high as 62.5 g·h<sup>-1</sup>·m<sup>-2</sup>.展开更多
Poly (lactic acid) (PLA) was synthesized by microwave-assisted ring-opening polymerization of D, L-lactide with stannous octanoate (SnOct(2)) as catalyst. Its weight-average molar mass (M-w) ranged from 39000 to 67000...Poly (lactic acid) (PLA) was synthesized by microwave-assisted ring-opening polymerization of D, L-lactide with stannous octanoate (SnOct(2)) as catalyst. Its weight-average molar mass (M-w) ranged from 39000 to 67000 and the polydispersity index from 1.3 to 1.7. The polymerization rate was much faster than that of the conventional thermal polymerization. A degradation of newly formed PLA in reaction mixture by microwave irradiation was observed.展开更多
PDLLA/CHI/β-TCP/NGF composite films were prepared by a solvent evaporation method. The degradation characteristics of the poly (d, l-lactide) composite films were studied in vitro and in vivo. The acidity produced ...PDLLA/CHI/β-TCP/NGF composite films were prepared by a solvent evaporation method. The degradation characteristics of the poly (d, l-lactide) composite films were studied in vitro and in vivo. The acidity produced by poly (d, l-lactide) materials was not obvious. Adding chitosan and β-TCP can relieve the acidity problem and improve strength performance of films. The NGF has influences on the degradation characteristics of films. It is verified that PDLLA/CHI/β-TCP/NGF composite films prepared by solvent evaporation method have excellent degradation characteristics. It can be used as a perfect biomaterial for repairing nerve injuries.展开更多
The toughened poly(L-lactic acid)/poly(butylene succinate-butylene terephthalate)(PLLA/PBST) blend with enhanced melt strength and excellent low temperature toughness and strength was prepared by melt compounding thro...The toughened poly(L-lactic acid)/poly(butylene succinate-butylene terephthalate)(PLLA/PBST) blend with enhanced melt strength and excellent low temperature toughness and strength was prepared by melt compounding through in situ compatibilization reaction in presence of multifunctional epoxy compound(ADR).The PLLA/PBST blend was an immiscible system,and the compatibility of the PLLA/PBST blend was improved after adding ADR.FTIR and GPC curves confirmed the formation of the PLLA-g-PBST copolymer,which improved the interfacial bonding of the blend and therefore the PLLA/PBST/ADR blend showed excellent melt strength and mechanical properties.For the PLLA/PBST/ADR blend with 70/30 PLLA/PBST content,the complex viscosity increased significantly with increasing ADR content.Moreover,the tensile strength,elongation at break and impact strength all increased obviously with increasing the ADR content.The elongation at break of the blend reached the maximum value of 392.7%,which was 93.2 times that of neat PLLA.And the impact strength of the blend reached the maximum value of 74.7 k J/m~2,which was 21.3 times that of neat PLLA.Interestingly,the PLLA/PBST/ADR blend exhibited excellent lowtemperature toughness and strength.At –20 ℃,the elongation at break of the PLLA/PBST/ADR blend was as high as 93.2%,and the impact strength reached 18.8 k J/m~2.Meanwhile,the tensile strength of the blend at low temperature was also high(64.7 MPa),which was beneficial to the application of PLA in the low temperature field.In addition,the PLLA/PBST/ADR blend maintaind good biodegradability,which was of great significance to the wide application of PLLA.展开更多
A novel cyclodextrin-containing polymer was prepared by graftingβ-cyclodextrin onto the backbone of poly(D,L-lactic acid)(PLA).First,mono(6-(2-aminoethyl)amino-6-deoxy)-β-cyclodextrin(β-CD-6-en)was prepared by sulf...A novel cyclodextrin-containing polymer was prepared by graftingβ-cyclodextrin onto the backbone of poly(D,L-lactic acid)(PLA).First,mono(6-(2-aminoethyl)amino-6-deoxy)-β-cyclodextrin(β-CD-6-en)was prepared by sulfonylation and amination ofβ-cyclodextrin and modified poly(D,L-lactic acid)(MPLA)was prepared by free radical polymerization of maleic anhydride and PLA.Then,grafting ofβ-cyclodextrin derivative to MPLA backbone was carried out by N-acylation reaction of MPLA andβ-CD-6-en in dimethyl formamide.The synthetic polymer(PLA-β-CD)was characterized by FTIR(Fourier transform infrared)spectroscopy and proton nuclear magnetic resonance(1H NMR)spectroscopy.The results demonstrated that,in the context of remaining the chain structure of PLA,the content ofβ-CD-6-en is 1.6%by the developed synthetic method.展开更多
基金This study was supported by the National Natural Science Foundation of China(No.30270395 and 30300084)the National"863"Project(No.2003AA32X210).
文摘A novel poly(d, /-lactic acid) (PDLLA) based biomimetic polymer was synthesized by grafting maleic anhydride, butanediamine and arg-gly-asp-ser (RGDS) peptides onto the backbone of PDLLA, aiming to overcome the acidity and auto-accelerating degradation of PDLLA during degradation and to improve its biospecificity and biocompatibility. The synthetic copolymer was characterized by FTIR, ^13C NMR and amino acid analyzer (AAA).
基金sponsored by the Science and Technology Foundation of Tianjin Health Bureau,No. 2010ky04the Application Basis and Front Technology Projects of Tianjin (Science and Technology Foundation of Tianjin),No.12JCYBJC18000
文摘Inhibition of neurite growth, which is in large part mediated by the Nogo-66 receptor, affects neural regeneration following bone marrow mesenchymal stem cell transplantation. The tissue engineering scaffold poly(D,L-lactide-co-glycolic acid) has good histocompatibility and can promote the growth of regenerating nerve fibers. The present study used small interfering RNA to silence Nogo-66 receptor gene expression in bone marrow mesenchymal stem cells and Schwann cells, which were subsequently transplanted with poly(D,L-lactide-co-glycolic acid) into the spinal cord lesion regions in rats. Simultaneously, rats treated with scaffold only were taken as the control group. Hematoxylin-eosin staining and immunohistochemistry revealed that at 4 weeks after transplantation, rats had good motor function of the hind limb after treatment with Nogo-66 receptor gene-silenced ceils prus the poly(O,L-lactide-co-glycolic acid) scaffold compared with rats treated with scaffold only, and the number of bone marrow mesenchymal stem cells and neuron-like cells was also increased. At 8 weeks after transplantation, horseradish peroxidase tracing and transmission electron microscopy showed a large number of unmyelinated and myelinated nerve fibers, as well as intact regenerating axonal myelin sheath following spinal cord hemisection injury. These experimental findings indicate that transplantation of Nogo-66 receptor gene-silenced bone marrow mesenchymal stem cells and Schwann cells plus a poly(D,L-lactide-co-glycolic acid) scaffold can significantly enhance axonal regeneration of spinal cord neurons and improve motor function of the extremities in rats following spinal cord injury.
文摘Biodegradable chitosan-g-poly (D, L-lactic acid) copolymers were prepared via two methods. (1) The lactide was grafted onto hydroxyl groups of chitosan by using macromolecular initiator sodium of trimethylsilyl-chitosan, (2) poly (D,L-lactic acid)(PLA) with low molecular weight can be linked to the amino group by coupling activated PLA to trimethylsilyl-chitosan. Two graft copolymers had hydrophilic-hydrophobic character and can be applied as carriers for drug delivery.
基金This work was financially supported by the following funds:Hunan Provincial Natural Foundation of China(2019JJ50472)Opening Fund of National&Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources(KF201802)+4 种基金Hunan Province Key Field R&D Program Project(2019GK2246)Education Department of Hunan Province Key Project(19A391)Key scientific research project of Huaihua University(HHUY2019-04)Special Project of Innovative Provincial Construction in Hunan Province(2020RC1013)Huaihua Key Laboratory for Preparation of Ceramic Materials and Devices and Science and Technology Plan Project of Huaihua City(2020R3101).
文摘Poly(L-lactic acid)(PLLA)is a thermoplastic material with complete degradability,high biocompatibility and excellent mechanical properties.It can replace petroleum-based polymers are currently being used in the fields of packaging,agriculture,textiles,medical and so on.However,PLLA’s extremely flammability greatly limits its wider application.An bio-based flame retardant L-APP/PLLA composites was prepared by melt blending of the L-APP and PLLA.The morphology,impact properties,thermal properties and flame retardant properties of composites were investigated by field emission scanning electron microscope(SEM),impact tester,differential scanning calorimeter(DSC),thermogravimetric analyzer(TGA),limiting oxygen indexer(LOI)and horizontalvertical burning tester.The results showed that the degree of crystallization(X_(c))and LOI of L-APP/PLLA composites increased as increasing of L-APP content.What’s more,the impact strength first increased and then decreased,the glass transition temperature(T_(g))and melting temperature(T_(m))do not changed significantly.The impact strength of composites was 9.1 kJ/m^(2) at a 5 wt%loading for L-APP,which was the highest level.When the content of L-APP was 20%,the LOI was 30.8%,the Xc was 42.3%and the UL-94 level was V-0.This research can promote the value-added utilization of lignin and the application of PLLA in the fields of flame retardant materials.
基金The authors thank the Ministry of Science and Technology,the National Natural Science Foundation of China and the Ministry of Education of China for supporting of this research(Grant No.G199905305,59973014 and 98005620,respectively).
文摘In this paper, the surface structure of poly(L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with carboxyl groups, sothat these functional groups could become the reactive sites for gelatin immobilization. The functional groups of the PLLAfilms were identified by ATR-FTIR spectra and XPS spectra, the changes in surface morphology were observed by usingenvironmental scanning electron microscopy (ESEM), and the hydrophilicity of modified PLLA films was examined bywater contact angle measurement. Experimental results showed that the gelatin was immobilized with water-solublecarbodiimide (EDC) onto the PLLA film's surfaces, and the gelatin content on the polymer surface was related to carboxylicgroup formed in the controlled hydrolysis process. Rough surfaces caused by hydrolysis will predominantly favor the adhesion and growth of cell; and the hydrophilicity of these surfaces after the modification procedure is enhanced.
文摘Objective:To observe the changing of biomechanical features during the degradation course of poly-D,L-lactic acid (PDLLA) rods in vivo and in vitro and to evaluate its value as an internal fixation material. Methods:PDLLA rods were emerged into PBS simultaneous body fluid with constant temperature of 37 C and the rods were embedded into muscle tissue of 20 rabbits for degradation in vitro and in vivo . The rods were taken out in 2, 4, 6. 8 and 12 weeks. Biomechanical features of bending, shearing and axial compression strength, rigidity and elastic modulus were observed during the degradation course. Statistical method was used to test the changes of biomechanical parameters. Results: (1) There was similar changes of bending, compressive, shearing strength and bending, compressive and shearing rigidity of the PDLLA rods between in vivo and in vitro. (2)Bending, compressive, shearing strength decreased 33%, 18% and 43% respectively within the first stage of the degradation, and after 6 weeks of degradation, they decreased slowly. (3)Elastic modulus, bending, compressive and shearing rigidity.decreased sharply during the 6 weeks of degradation, with a drop of 22% , 39% and 30% respectively, and after 8 weeks, they decreased slowly. Even after 12 weeks of degradation, the strength of the rods was still higher than that of sponge bone. Conclusion: During the degradation of the material, the strength and rigidity of PDLLA rods can meet the need of fracture fixation of cancellous bones.
基金funded by the Russian Ministry of Education and Science(state contract no.14.W03.31.0014,MegaGrant).
文摘The biocomposite films were prepared from poly(L-lactic acid)and cellulose nanocrystals.To improve interfacial compatibility of hydrophilic cellulose nanocrystals with hydrophobic matrix polymer as well as to provide the osteoconductive properties,cellulose was functionalized with poly(glutamic acid).The modified cellulose nanocrystals were better distributed and less aggregated within the matrix,which was testified by scanning electron,optical and polarized light microscopy.According to mechanical tests,composites filled with nanocrystals modified with PGlu demonstrated higher values of Young’s modulus,elongation at break and tensile strength.Incubation of composite materials in model buffer solutions for 30 weeks followed with staining of Ca^(2+)deposits with Alizarin Red S assay testified better mineralization of materials containing PGlu-modified cellulose nanocrystals as filler.As the result of in vivo experiment,the developed composite materials showed less level of inflammation in comparison with pure polymer matrix and composites filled with non-functionalized cellulose nanocrystals.
基金supported by the National Natural Science Foundation of China,No.51073072the Natural Science Foundation of Zhejiang Province in China,No.Y4100745+1 种基金the Key Laboratory Open Foundation of Advanced Textile Materials&Manufacturing Technology of Zhejiang Sci-Tech University from Ministry of Education of China,No.2009007the Science and Technology Commission of Jiaxing Municipality Program,No.2010AY1089
文摘In this study, poly(L-lactic acid)/ammonium persulfate doped-polypyrrole composite fibrous scaffolds with moderate conductivity were produced by combining electrospinning with in situ polymerization. PC12 cells were cultured on these fibrous scaffolds and their growth following electrical stimulation (0-20.0 μA stimulus intensity, for 1-4 days) was observed using inverted light microscopy, and scanning electron microscopy coupled with the MTT cell viability test. The results demonstrated that the poly(L-lactic acid)/ammonium persulfate doped-polypyrrole fibrous scaffold was a dual multi-porous micro/nano fibrous scaffold. An electrical stimulation with a current intensity 5.0- 10.0 μAfor about 2 days enhanced neuronal growth and neurite outgrowth, while a high current intensity (over 15.0 μA) suppressed them. These results indicate that electrical stimulation with a moderate current intensity for an optimum time frame can promote neuronal growth and neurite outgrowth in an intensity- and time-dependent manner.
基金Supported by the National Natural Science Foundation of China.
文摘A rotating disk contactor(RDC)was designed to perform L-lactic acid fermentation with afilamentous fungi,Rhizopus oryzae,which was immobilized on the surfaces of the rotating discs.Thebioreactor was operated using repeated-batch method as well as continuous feeding method.Ananionic resin,D354,slightly basic in nature and of high selectivity and capacity was chosen for lacticacid separation.A coupled process of L-lactic acid fermentation and ion-exchange separation wasevaluated experimentally.The results indicated that the pH value of the fermentation broth could bemaintained at about 3-3.5 without any addition of alkali.The conversion ratio of glucose to L-lacticacid was about 0.7 g·g<sup>-1</sup> and the fermentation rate reached as high as 62.5 g·h<sup>-1</sup>·m<sup>-2</sup>.
文摘Poly (lactic acid) (PLA) was synthesized by microwave-assisted ring-opening polymerization of D, L-lactide with stannous octanoate (SnOct(2)) as catalyst. Its weight-average molar mass (M-w) ranged from 39000 to 67000 and the polydispersity index from 1.3 to 1.7. The polymerization rate was much faster than that of the conventional thermal polymerization. A degradation of newly formed PLA in reaction mixture by microwave irradiation was observed.
文摘PDLLA/CHI/β-TCP/NGF composite films were prepared by a solvent evaporation method. The degradation characteristics of the poly (d, l-lactide) composite films were studied in vitro and in vivo. The acidity produced by poly (d, l-lactide) materials was not obvious. Adding chitosan and β-TCP can relieve the acidity problem and improve strength performance of films. The NGF has influences on the degradation characteristics of films. It is verified that PDLLA/CHI/β-TCP/NGF composite films prepared by solvent evaporation method have excellent degradation characteristics. It can be used as a perfect biomaterial for repairing nerve injuries.
基金financially supported by the Science and Technology Development Plan of Jilin Province (No. 20210203199SF)。
文摘The toughened poly(L-lactic acid)/poly(butylene succinate-butylene terephthalate)(PLLA/PBST) blend with enhanced melt strength and excellent low temperature toughness and strength was prepared by melt compounding through in situ compatibilization reaction in presence of multifunctional epoxy compound(ADR).The PLLA/PBST blend was an immiscible system,and the compatibility of the PLLA/PBST blend was improved after adding ADR.FTIR and GPC curves confirmed the formation of the PLLA-g-PBST copolymer,which improved the interfacial bonding of the blend and therefore the PLLA/PBST/ADR blend showed excellent melt strength and mechanical properties.For the PLLA/PBST/ADR blend with 70/30 PLLA/PBST content,the complex viscosity increased significantly with increasing ADR content.Moreover,the tensile strength,elongation at break and impact strength all increased obviously with increasing the ADR content.The elongation at break of the blend reached the maximum value of 392.7%,which was 93.2 times that of neat PLLA.And the impact strength of the blend reached the maximum value of 74.7 k J/m~2,which was 21.3 times that of neat PLLA.Interestingly,the PLLA/PBST/ADR blend exhibited excellent lowtemperature toughness and strength.At –20 ℃,the elongation at break of the PLLA/PBST/ADR blend was as high as 93.2%,and the impact strength reached 18.8 k J/m~2.Meanwhile,the tensile strength of the blend at low temperature was also high(64.7 MPa),which was beneficial to the application of PLA in the low temperature field.In addition,the PLLA/PBST/ADR blend maintaind good biodegradability,which was of great significance to the wide application of PLLA.
基金Funded by the Natural Science Foundation of China(No.50603032)Education Commission of Chongqing(No.KJ090617)the Science and Technology Plan Project of Jiulongpo District,Chongqing,China(No.2008Q95)
文摘A novel cyclodextrin-containing polymer was prepared by graftingβ-cyclodextrin onto the backbone of poly(D,L-lactic acid)(PLA).First,mono(6-(2-aminoethyl)amino-6-deoxy)-β-cyclodextrin(β-CD-6-en)was prepared by sulfonylation and amination ofβ-cyclodextrin and modified poly(D,L-lactic acid)(MPLA)was prepared by free radical polymerization of maleic anhydride and PLA.Then,grafting ofβ-cyclodextrin derivative to MPLA backbone was carried out by N-acylation reaction of MPLA andβ-CD-6-en in dimethyl formamide.The synthetic polymer(PLA-β-CD)was characterized by FTIR(Fourier transform infrared)spectroscopy and proton nuclear magnetic resonance(1H NMR)spectroscopy.The results demonstrated that,in the context of remaining the chain structure of PLA,the content ofβ-CD-6-en is 1.6%by the developed synthetic method.