Preparation And Properties Of PLLA-based Antibacterial Shape Memory Polymer Composites

Poly(lactic acid)biodegradable shape memory polymer had good biocompatibility,biodegradability and unique shape memory effect.It had been widely used in the field of biomedicine,but its insufficient mechanical strength,single shape memory function and lack of biological function limit its further application in the field of medicine.In this paper,in view of the above shortcomings,the materials not only possess improved mechanical properties but also have antibacterial properties and multi-induced shape memory effect were fabricated through selecting nanoparticles with special functions as reinforcement phase.In this paper,the surface of GO was modified by L-lactic acid solution polymerization to prepare polylactic acid(PLLA)grafted graphene oxide(g-GO).The g-GO/poly(l-lactide-co-?-caprolactone)composites(g-GO/PLCL)were prepared by solution blending method.Tensile test results showed that the elastic modulus,tensile strength and elongation at break of the gGO/PLCL composites reached the maximum when the g-GO content was 1.0wt%.Cyclic tensile test results showed that(1.0wt%)g-GO/PLCL composite had the best heat-induced shape memory effect with shape retention rate and shape recovery rate of 98.8% and 98.9%,respectively.At the same time,under the irradiation of current intensity of 100 m A near infrared light,shape recovery could be completed within 4s,with a high shape recovery ratio of 97%.The addition of g-GO accelerated the degradation rate of the materials,and g-GO/PLCL composites had certain antibacterial properties.When the g-GO content was 1.0wt%,the antibacterial rate of the composites against E.coli and S.ureus was 72.1% and 84.2%,respectively.The surface of magnesium oxide nanoparticles(Mg O)was modified by polydopamine(PDA),and at the same time PDA-modified Mg O/NCC composite nanoparticles(PDAMg O/NCC)was prepared by incorporation with nanocellulose(NCC).The(PDAMg O/NCC)/PLLA/PLCL composites were prepared by solution blending method.Tensile test results showed that the addition of PDA-Mg O/NCC composite nanoparticles content was 4wt%,the elastic modulus,tensile strength and elongation at break of the composites reached the maximum.(PDA-Mg O/NCC)/PLLA/PLCL composite had good thermal induced shape memory effect and good water induced shape memory effect.When the content of PDAMg O/NCC composite nanoparticles was 4wt%,the shape recovery ratio of the composite reached 90.8% in 40? water environment.When the content of PDA-Mg O/NCC composite nanoparticles was 4wt%,the antibacterial rate of the composites against E.coli and S.aureus was 72.8% and 71.1%,respectively.