Polymer/Inorganic Nanohybrid Materials:Synthesis And Biomimetic Water-based Lubrication

In this thesis,the research progress of joint lubrication and bionic water lubricating materials were reviewed.The superiorlubrication performance of human synovial joints could inspire scientists to develop biomimetic polymer-based lubricants by utlizing advanced synthetic methods.The biomimetic lubricants could provide possible solutions for osteoarthritis treatment,artificial joint lubrication,and surface lubrication of implantable/interventional medical devices.They can also offer technical supports for industrial water-based lubrication.In addition,inorganic nanomaterials have been widely used in water-based lubricating additives,which exhibited excellent anti-friction and anti-wear properties through roll or slip effects during friction process.Therefore,in this thesis,biomimetic hydrophilic polymers were rationally combined with inorganic nanomaterialsto develop a series of polymer/inorganic nano hybrids via facile,robust and biocompatible synthetic methods.The applications of these nanohybrids as nanoadditives of lubrication were investigated,including industrial water-based lubrication and bio-lubrication.The main research contents and results are as follows:1.In this part,graphene oxide(GO)and brush-like polysaccharide-based copolymer(chitosan-graft-poly(N-isopropylacrylamide),Chitosan-g-PNIPAM)was rationally combined to develop novel hybrid additives for water-based lubrication.The GO/Chitosan-g-PNIPAM nanohybrids were prepared by a facile in-situ non-covalent assembly method.Non-covalent functionalization of GO can not only improve the stability of GO,but also enhance the tribological properties.Compared with the preparations of previous polymer/GO nanohybrids,this method is facile,robust and eco-friendly without utilizing any toxic reagents and organic solvent.Additionally,chitosan is a type of naturally-derived polymer with biocompatibility and degradation.These features make the nanohybrids a type of green nanoadditives for water-based lubrication.Tribological tests demonstrated significant friction-reducing and anti-wear capabilities compared with pure water and individual GO and copolymers.The excellent lubricating properties of the nanohybrid may be attributed to the dispersion stability of the modified GO and the synergistic effect between brush-like copolymer and 2D GO.Furthermore,this work provides a novel approach to develop green nanoadditives for water-based lubrication through rational combination of 2D materials and brush-like polymer.2.Dual-functional nanohybrids with simultaneously lubrication and drug-loading ability were fabricated for treatment of osteoarthritis.Dopamine-triggered polymerization of acrylate monomers,a novel surface modification method,was empolyed to functionalize to hollow mesoporous silicon dioxide(h-SiO₂).The hydrophilic poly(3-sulfopropyl methacrylate potassium)(PSPMA)was deposited on h-SiO₂ via polydopamine(PDA)assisted co-deposition to result in h-SiO₂/PDA-PSPMA nanohybrid.The h-SiO₂ can be used to load drugs for treating osteoarthritis.The PDA-PSPMA layer with strong hydration ability endowed h-SiO₂with excellent lubrication performance.Tribological evaluations showed that h-SiO₂/PDA-PSPMA has excellent lubricating properties on the surface of different substrates.The coefficient of friction is as low as 0.015.Furthermore,the as-prepared h-SiO₂/PDA-PSPMA exhibited better lubrication performance than commercial hyaluronic acid when using degraded cartilage as a substrate.In addition,h-SiO₂/PDA-PSPMA can slowly release anti-inflammatory and analgesic drug(diclofenac sodium),achieving simultaneous lubrication and drug delivery.Therefore,h-SiO₂/PDA-PSPMA is expected to have potential applications for the lubrication artificial joint and osteoarthritis treatment.