Synthesized Polyesteramide And Polyester-grafted Methacrylate Copolymer For Modifying Poly(Lactic Acide)

With the increasing consumption of petroleum resources and increasing awareness of low-carbon environmental protection,polylactic acid(PLA)has attracted widespread attention as a mature biodegradable polymer.Because of its good biocompatibility/degradability,PLA is mainly used in related fields such as biomedicine and ecological environment protection,but its low thermal/mechanical properties and toughness limit the scope of application.In order to fully explore the properties of PLA,it is of practical research value to blend and modify it.At the same time,polyester amide(PEA)can combine the biocompatibility and biodegradability of polyester with the thermal and mechanical properties of polyamide.Alpha-amino acid-containing PEA can improve the biological properties of polymer materials.Therefore,the application of?-amino acid-containing PEA and PLA to form electrospun nanofiber membranes in the field of biological tissue engineering scaffolds has become a hot research direction.In this section,Biodegradable P-(CL-EA-CL)?P-(N-CL-EA-CL-N)polyester amide containing ethylene glycol,L-alanine,N-benzyloxycarbonyl-L-aspartic acid,and caprolactone in the main chain was synthesized by solution polymerization and chain extension methods,product synthesis was confirmed by FTIR and ~1H NMR.Blended with polylactic acid(PLLA)for electrospinning to prepare PLLA/P-(CL-EA-CL),PLLA/P-(N-CL-EA-CL-N)composite nanofiber membranes.The fiber membrane was characterized by DSC,SEM,contact angle,mechanical properties,degradation behavior and cytotoxicity.The results show that the addition of P-(CL-EA-CL)polyesteramide improves the mechanical properties of the fiber membrane,and the hydrophilicity of the fiber membrane is also significantly improved.When the blending ratio is 30 wt%and the graft ratio is 1:4,the tensile strength of the PLLA/P-(CL-EA-CL)-1 blended film is 11.43 MPa,and the elongation at break is 56.21%.The hydrophilic angle was reduced from 138.2~o to 76.3~o for pure PLLA fiber membrane.Compared with pure PLLA fiber membrane,the tensile strength of PLLA/P-(N-CL-EA-CL-N)-1 fiber membrane is basically unchanged,and the elongation at break is slightly reduced.The hydrophilic angle was reduced from138.2~o of pure PLLA fiber membrane to 71.6~o,and the hydrophilicity of the blended fiber membrane was significantly improved.Compared to PLLA/P-(CL-EA-CL)-1fiber membrane,The 30 wt%PLLA/P-(N-CL-EA-CL-N)-1 blend membrane has improved hydrophilicity and cytotoxicity,its tensile strength is 9.02 MPa,elongation at break is 35.60%.The mechanical properties meet the application conditions of tissue engineering scaffolds.It can be seen from the SEM that the surface of the blended fiber membrane is smooth and the thickness is relatively uniform,and the overall shape is good.Degradation experiments in different environments also found that the blended fiber membrane had alkaline degradation sensitivity.Cytotoxicity tests further characterize the good biocompatibility of the blended membranes.Therefore,PLLA/P-(CL-EA-CL)and PLLA/P-(N-CL-EA-CL-N)composite nanofiber membranes have application potential in the field of biological tissue engineering.Polymethacrylate polymers have excellent mechanical properties,In this section,a series of biodegradable polyester graft modified polyacrylate copolymers are synthesized to improve the toughness of PLLA,and the effects of main chain,side chain,compatibilizer and external tension on toughened PLLA are revealed.The elongation at break and tensile strength of pure PLLA film were 6.6%and 43.7 MPa,respectively.When the synthesized PMH-PCL is blended with PLLA,the elongation at break is greatly increased,and the tensile strength is slightly decreased.They are81.3%and 32.8 MPa,respectively.When the grafted side chain is L-LA,the tensile strength of the blended film is high,but its toughening effect is not significant.Adding an appropriate amount of TBC can significantly increase the elongation at break,but the tensile strength is further reduced to 27.3 MPa.Mechanical processes are simulated by applying external tension during the drying process.Under the external force of 100 g,the elongation at break of the PLLA/PMH-PCL blend was reduced to 68.7%within 50 days,and the tensile strength was basically unchanged.Therefore,toughened PLLA can withstand the test of machining.