Researches On Halloysite Nano-coating Modified Polylactic Acid Sheet And Polyurethane Sponge

Halloysite nanotubes(HNTs)are natural mineral nanomaterials with unique structures and properties.Halloysite in functional materials,biological medicine,environmental remediation and other high-tech fields has important application value.It is of great significance to use natural tubular nano clay halloysite coating to modify polymer materials.Therefore,in this graduation thesis,sheet-shaped polylactic acid(PLA)and sponge-like polyurethane(PU)are selected as the polymer matrix.Through different interaction mechanisms,halloysite nano-coatings are coated on the surface of these two forms of polymer materials.The physical and chemical properties and practical applications of the new type of halloysite nano-coating modified polymer materials are systematically studied.In this research,a green,environmentally friendly,efficient and inexpensive sample preparation method is used.The research provides a new method for the preparation of high-performance polymer materials and functional materials.Halloysite-coating modified polymer materials have broad application prospects in tissue engineering,environmental remediation,large-scale oil spills and other fields.In view of good biocompatibility and cell capture ability of HNTs,the work combines 3D printing technology of PLA and good adhesion of polydopamine(PDA)to prepare a low-cost,high-performance cell-oriented materials.In order to improve the ability of cell orientation of sheets,3D printed PLA sheets are immersed in dopamine and halloysite dispersion.The catechol structure of bio-adhesive PDA can form covalent bonds with hydroxyl groups on the surface of PLA and HNTs.Thus,the halloysite nano coating is applied uniformly coated on the PLA surface.The dopamine-modified HNTs(PDA@HNTs)coating not only improves the roughness and hydrophilicity of PLA,but also maintains the adhesion and adhesion of cells.In addition,the coating also achieves the directed growth of mouse pre-osteoblasts and human bone mesenchymal stem cells.In view of good high temperature resistance and adsorption performance of HNTs,the work combines good porous structure of PU sponge and efficient dip-coating method to prepare a two-in-one multifunctional sponge with good absorbency and flame retardancy.In order to improve the temperature resistance and dye adsorption of sponge,PU sponge is immersed in halloysite dispersion.This halloysite nano-coating is uniformly bonded to the PU sponge surface through interactions such as hydrogen bonding.The coated PU sponge can still maintain a high porosity,and the surface changes from hydrophobic to super-hydrophilic.The adsorption capacity of HNTs-coated PU(HNTs-PU)sponge is increased more than seven times.In addition,the halloysite nano-coating significantly improves the flame retardant of PU sponge.HNTs-PU sponge can be self-extinguished to prevent the sponge from melting and dripping.In view of nano-roughness and high specific surface area of HNTs,the work combines good porous structure of PU sponge and low surface free energy of hexadecyltrimethoxysilane(HDTMS)to prepare a super-hydrophobic PU sponge with high oil absorption capacity.In order to change the surface morphology and hydrophobicity of sponge,PU sponge is immersed in hydrophobic HNTs(POS@HNTs)dispersion.POS@HNTs are prepared by surface graft modification with HDTMS and ethyl orthosilicate.POS@HNTs coating is uniformly bonded to the PU sponge surface through physical interaction.The modified PU(POS@HNTs-PU)sponge not only greatly increases the water contact angle,but also has highly selective absorption capacity for oil and organic solvents.In addition,the super-hydrophobic sponge also shows good recyclability and can separate oil and organic solvents from water continuously,efficiently and quickly.