Study On The Interfacial Behavior Of Janus Particles In PPDO/PLA Composites

Poly（p-dioxanone）（PPDO）has good biocompatibility and degradability,and is widely used in biomedical materials.In order to improve its hydrophobicity and crystallinity,it is often blended with polylactic acid（PLA）.In this paper,the phase separation method was used to prepare the Janus particles（JPs）based on SiO₂@PS template and silica Janus nanosheets（JNSs）.The compatibilizing effects of three kinds of JPs with different hydrophilic lipophilic balance（HLB）values and JNSs with higher specific surface area on PPDO/PLA composites were compared.1.Three kinds of snowman-like JPs with different HLB values were prepared by one-pot method by adjusting the surficial functional groups of polystyrene（PS）side and used as the compatibilizer of PPDO/PLA composites.JPs self-assemble at the cell-structure PPDO/PLA interface,which provides channels for the migration of PPDO.The silica（SiO₂）side forms hydrogen bond with PLA,and the PS side forms hydrophobic action with PPDO.JPs improve interfacial adhension and suppress phase separation.Among the three JPs,silica@polystyrene-polydivinylbenzene（SiO₂@PS-PDVB）and silica@polystyrene-polymethylmethacrylate（SiO₂@PS-PMMA）JPs have similar HLB values to PPDO/PLA composites,so they possess good compatibilization effect.Tensile strength increased from the original 14.59 MPa to the maximum 24.18 MPa at 1.5 phr of SiO₂@PS-PMMA JPs,and the elongation at break increased from 39%to 203%.The sulfhydryl group at the side of SiO₂ reacts with human tissues,and JPs are expected to be used to strengthen and toughen immiscible biopolymer mixtures.2.JNSs were synthesized by one-step method,and their asymmetric morphology and chemical composition were tested by SEM,EDX,XPS,FTIR,and TGA.Then,JNSs were used as the toughening agent of PLA,and the morphology,composition and mechanical properties of PLA/JNSs composites were studied.JNSs have excellent toughening effect on PLA.The elongation at break of PLA/JNSs composites increased from the original 6.6%to the maximum of 81.3%at 0.5 phr of JNSs.Moreover,the sheet-like JNSs showed obvious thermal barrier effect.3.JNSs were used as the compatibilizer of PPDO/PLA composites,and the effects of JNSs on the compatibilization,viscoelasticity,and mechanical properties of PPDO/PLA composites were investigated.The arched JNSs tightly hold PLA dispersed phase with chemical bonds on the inner surface accompanied with Van der Waals force on the outer surface.The synergistic effect of chemical bonds,concavo-convex fitted gripper,and orientation leads to the simultaneous increase in the strength and toughness of PPDO/PLA/JNSs composites.The tensile strength increased from the original 24.68MPa to the maximum of 28.79 MPa at 0.05 phr of JNSs,and at the same time,the elongation at break increased from 128.7%to 407.8%.JNSs with sheet structure has higher specific surface area,and the compatibilization of JNSs with 0.05 phr on PPDO/PLA composites is more than 1.5 phr of JPs.