Multiwalled carbon nanotubes(MWCNTs) grafted with poly(L-lactide-e-caprolactone)(PCLA) were synthesized by ring opening polymerization reaction and used as a reinforcement for neat PCLA.Scanning electron microscopy(SE...Multiwalled carbon nanotubes(MWCNTs) grafted with poly(L-lactide-e-caprolactone)(PCLA) were synthesized by ring opening polymerization reaction and used as a reinforcement for neat PCLA.Scanning electron microscopy(SEM) revealed that the applied tensile load on the composite was transferred to the MWNT-OH-g-PCLA,loading to a strain failure of the MWCNTs rather than an adhesive failure between the MWCNTs and the matrix.展开更多
The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PC...The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.展开更多
Poly(e-caprolactone) (PCL) with weight-average molar mass over 10000 g/mol was synthesized by microwave-assisted ring-opening polymerization of e-caprolactone (e-CL) with maleic acid (MA) as initiator (2.45 GHz, 360 W...Poly(e-caprolactone) (PCL) with weight-average molar mass over 10000 g/mol was synthesized by microwave-assisted ring-opening polymerization of e-caprolactone (e-CL) with maleic acid (MA) as initiator (2.45 GHz, 360 W, 85 min). Ibuprofen-PCL controlled release system was prepared directly by the ROP of e-CL in its mixture with ibuprofen. The release of ibuprofen from the system was sustained and steady.展开更多
Self-healing poly(urea-urethane)s (PUUs) showing a tolerance to mechanical damage are particularly desirable for high-performance elastomeric biomaterials. In this study a kind of biodegradable PUUs was synthesize...Self-healing poly(urea-urethane)s (PUUs) showing a tolerance to mechanical damage are particularly desirable for high-performance elastomeric biomaterials. In this study a kind of biodegradable PUUs was synthesized from poly(e-caprolactone) diol with L-lysine ethyl ester diisocyanate (LDI) extended with L-lysine ethyl ester dihydrochloride (LEED) in DMF and characterized by using 1H-NMR, FTIR, DSC, XRD, SEM and tensile tests. Interestingly, they exhibited a self-healing characteristic upon exposure to 37℃ for as short as 30 min with the tensile strength keeping at 4.23 MPa and the elongation at break reaching to 627%. It is revealed that increasing the hard segment content in PUUs benefits the self-healing performance, and on the opposite increasing the soft segment content contributes to the biodegradability.展开更多
Mismatched biomechanical properties between artificial vascular grafts and native blood vessels can result in intimal hyperplasia,especially for the implantation of small-diameter blood vessels.Ideal biomaterials for ...Mismatched biomechanical properties between artificial vascular grafts and native blood vessels can result in intimal hyperplasia,especially for the implantation of small-diameter blood vessels.Ideal biomaterials for vascular repair still remain challenged.Biodegradable poly(ε-caprolactone)(PCL)has been applied for the preparation of electrospun vascular grafts,but more efforts are needed to improve its compliance with tissue growth.Herein,L-arginine-based poly(ester urethane)urea(PEUU)with both elasticity and biodegradability was synthesized so as to enhance the biomechanical properties of vascular grafts by blending electrospinning with PCL in a given mass ratio.It was exhibited that the prepared electrospun PCL/PEUU fibrous membranes were suitable for cell proliferation with normal cell morphology.More importantly,the electrospun membrane with 1/1 mass ratio of PCL/PEUU(PEUU50)showed specific flexibility,exhibiting more suitable mechanical properties matching to the native blood vessels.Specifically,the PEUU50 electrospun membrane demonstrated significantly lower Young’s modulus(9.3±0.8 MPa)and tensile strength(6.0±0.5 MPa),and extremely higher elongation(389%±24%)in wet state than those(16.3±3.0 MPa,11.4±7.1 MPa and 196%±57%,respectively)of the pristine PCL membrane.Overall,this study demonstrated the great potential of amino acid-based PEUUs for the application in small-diameter vascular grafts.展开更多
The poly(2,2-dimethyltrimethylene carbonate) (PDTC) with one hydroxyl and one formate terminal functions was synthesized by in situ generated, tetrahydrosalen stabilized yttrium borohydride complex. The influences...The poly(2,2-dimethyltrimethylene carbonate) (PDTC) with one hydroxyl and one formate terminal functions was synthesized by in situ generated, tetrahydrosalen stabilized yttrium borohydride complex. The influences of monomer/initiator molar ratio, temperature and reaction time on polymerization of DTC were investigated. Under the condition: [DTC]/[I] = 500, 55℃, toluene: 0.5 mL, DTC: 0.6 g, PDTC with Mn = 15600 and PDI = 2.15 was obtained. Through 1H-NMR and 13C-NMR analyses, the structure of PDTC was characterized and a coordination-insertion mechanism was proposed. In addition, the random copolymerization of DTC and caprolactone (CL) initiated by rare-earth borohydride compound was studied. The microstructure of PDTC-co-PCL includes four diads: DTC-CL, CL-CL, DTC-DTC and CL- DTC, which were determined by the specific signals in lH-NMR spectra. Based on the typical signals of the formate (δ = 8.08) and hydroxyl (δ= 3.34) end groups of PDTC-co-PCL, a mechanism involving DTC monomer inserts before CL during the initiation process was presumed. Furthermore, the thermal properties of amorphous copolymer were characterized by differential scanning calorimetry (DSC). The results support the random structure of PDTC-co-PCL.展开更多
基金Funded by the National Basic Research Program of China(No.2006CB708609)the Development Program for Outstanding Young Teachers in HIT (HITQNJS.2007.015)
文摘Multiwalled carbon nanotubes(MWCNTs) grafted with poly(L-lactide-e-caprolactone)(PCLA) were synthesized by ring opening polymerization reaction and used as a reinforcement for neat PCLA.Scanning electron microscopy(SEM) revealed that the applied tensile load on the composite was transferred to the MWNT-OH-g-PCLA,loading to a strain failure of the MWCNTs rather than an adhesive failure between the MWCNTs and the matrix.
基金supported by the National Natural Science Foundation of China.(Grant No.20174033 and 20254001)the Special Found for Major State Basic Research Project(Grant No.G1999064801)the Committee of Science and Technology of Zhejiang Province.
文摘The ring-opening polymerization of e-caprolactone (CL) initiated by novel single lanthanide tris(4-tert-butylphenolate)s [Ln(OTBP)3] is reported. Single-component La(OTBP)3 can effectively prepare polycaprolactone (PCL) with over 90% yield and viscosity average molecular weight about 60 x 10 under quite mild conditions: molar ratio of CL to initiator is 1000, 60 C, 2 h in toluene. Mechanism study indicates that the monomer inserts into the growing chain via the break of acyl-oxygen bond of CL.
基金This work was financially supported by the Research Foundation of MOE and National 973 Project of China (G1999064703).
文摘Poly(e-caprolactone) (PCL) with weight-average molar mass over 10000 g/mol was synthesized by microwave-assisted ring-opening polymerization of e-caprolactone (e-CL) with maleic acid (MA) as initiator (2.45 GHz, 360 W, 85 min). Ibuprofen-PCL controlled release system was prepared directly by the ROP of e-CL in its mixture with ibuprofen. The release of ibuprofen from the system was sustained and steady.
基金financially supported by the "863" Project of Minister of Science and Technology of China(No. 2007AA021905)
文摘Self-healing poly(urea-urethane)s (PUUs) showing a tolerance to mechanical damage are particularly desirable for high-performance elastomeric biomaterials. In this study a kind of biodegradable PUUs was synthesized from poly(e-caprolactone) diol with L-lysine ethyl ester diisocyanate (LDI) extended with L-lysine ethyl ester dihydrochloride (LEED) in DMF and characterized by using 1H-NMR, FTIR, DSC, XRD, SEM and tensile tests. Interestingly, they exhibited a self-healing characteristic upon exposure to 37℃ for as short as 30 min with the tensile strength keeping at 4.23 MPa and the elongation at break reaching to 627%. It is revealed that increasing the hard segment content in PUUs benefits the self-healing performance, and on the opposite increasing the soft segment content contributes to the biodegradability.
基金supported by the National Natural Science Foundation of China(Grant No.52073204)。
文摘Mismatched biomechanical properties between artificial vascular grafts and native blood vessels can result in intimal hyperplasia,especially for the implantation of small-diameter blood vessels.Ideal biomaterials for vascular repair still remain challenged.Biodegradable poly(ε-caprolactone)(PCL)has been applied for the preparation of electrospun vascular grafts,but more efforts are needed to improve its compliance with tissue growth.Herein,L-arginine-based poly(ester urethane)urea(PEUU)with both elasticity and biodegradability was synthesized so as to enhance the biomechanical properties of vascular grafts by blending electrospinning with PCL in a given mass ratio.It was exhibited that the prepared electrospun PCL/PEUU fibrous membranes were suitable for cell proliferation with normal cell morphology.More importantly,the electrospun membrane with 1/1 mass ratio of PCL/PEUU(PEUU50)showed specific flexibility,exhibiting more suitable mechanical properties matching to the native blood vessels.Specifically,the PEUU50 electrospun membrane demonstrated significantly lower Young’s modulus(9.3±0.8 MPa)and tensile strength(6.0±0.5 MPa),and extremely higher elongation(389%±24%)in wet state than those(16.3±3.0 MPa,11.4±7.1 MPa and 196%±57%,respectively)of the pristine PCL membrane.Overall,this study demonstrated the great potential of amino acid-based PEUUs for the application in small-diameter vascular grafts.
基金supported by the National Natural Science Foundation(Nos.20674071,20774078)the Special Funds for Major State Basic Research Projects(No.2005CB623802)
文摘The poly(2,2-dimethyltrimethylene carbonate) (PDTC) with one hydroxyl and one formate terminal functions was synthesized by in situ generated, tetrahydrosalen stabilized yttrium borohydride complex. The influences of monomer/initiator molar ratio, temperature and reaction time on polymerization of DTC were investigated. Under the condition: [DTC]/[I] = 500, 55℃, toluene: 0.5 mL, DTC: 0.6 g, PDTC with Mn = 15600 and PDI = 2.15 was obtained. Through 1H-NMR and 13C-NMR analyses, the structure of PDTC was characterized and a coordination-insertion mechanism was proposed. In addition, the random copolymerization of DTC and caprolactone (CL) initiated by rare-earth borohydride compound was studied. The microstructure of PDTC-co-PCL includes four diads: DTC-CL, CL-CL, DTC-DTC and CL- DTC, which were determined by the specific signals in lH-NMR spectra. Based on the typical signals of the formate (δ = 8.08) and hydroxyl (δ= 3.34) end groups of PDTC-co-PCL, a mechanism involving DTC monomer inserts before CL during the initiation process was presumed. Furthermore, the thermal properties of amorphous copolymer were characterized by differential scanning calorimetry (DSC). The results support the random structure of PDTC-co-PCL.