Preparation And Application Of Functional Polymer Nanomaterials Based Nano/micromachine

In the past decades,artificial nano/micromachine is one of the research hotspots in the field of nanotechnology.Nano/micromachine is a nano/microscale device that can move autonomously in solution or drive fluid flows by converting energy into mechanical work.More and more efforts have been exerted on studying of nano/micromachines.They are expected to play important roles in biomedical area,environmental remediation and sensing diverse potential applications.Currently,the building blocks of nano/micromachines are mostly based on inorganic materials,such as Au,Pt and SiO2.The construction methods are generally based on template synthesis or microfabrication technology(e.g.photolithography).Due to the limitation in the fabrication method,researches in man-made nano/micromachine haven't achieved mass production.Since the fabrication of a nano/micromachine itself already involves several steps,to develop a nano/micromachine that possesses multiple functions will inevitably increase the fabrication complexity.What is more,the biocompatibility of nano/micromachine and the biocompatibility of the fuel are the crucial steps towards the future requirement for the biomedical applications.This thesis mainly focuses on the fabrication of bipolymer polycaprolatone based multifunctional nano/micromotors.We also develop a fuel-free multifunctional nano/micromachine based on P3HT.The main results are as follows:1.The polymer lamellae can be mass produced through solution crystallization method.As compared to the inorganic materials,polymer is easyily end functionlized.When end-functionalized polymer is used as the starting material,the end-functional groups are excluded to the lamellae surface due to the the difference between polymer chain ends and the rest of the polymer backbone.The functionalized lamellae can be obtained via nanoparticle decoration through the interaction between nanoparticles and functional groups(e.g.thiol groups and hydroxyl groups).Here,by utilizing polycaprolactone(PCL)or polyethylene glycol(PEG)as the building blocks,we achieved a nano/micromotor through self-assembly method.We also have adopted the 4-nitrophenol reduction as the model reaction to assess the catalytic activity.2.Nanoparticles have attracted more and more attention due to their unique properties,such as silver nanoparticles with tunable surface plasmon resonance(SPR)and superparamagnetism for iron oxide nanoparticle and so on.A self-assembly method is employed to incorporate polycaprolactone lamellae and nanoparticle into a single nano/micromotor system,a multifunctional nano/micromotor is developed,which has functions of autonomous movement,controlled movement,enzymatic disassembly,sustained release of a model drug and detection of a solute.3.In addition,in order to increase the velocity of nano/micromotor fabricated by the self-assembly technique,we present two strategies:a,the speed of nano/micromotor can be increased 3 times by tuning the surface wettability of nano/micromotor;b,through applying an electric field or the synergetic effect between platinum and iron oxide nanoparticles can enhance the catalytic activity of platinum nanoparticle.All these strategies lead to the increase in speed,with the highest value reaching 200 ?m/s.4.We fabricated an all-polymer nano/micromotor based on environmental friendly polymeric materials,i.e.polycaprolactone and catalase,which function as the main polymer body and the 'engine',respectively.Then,by incorporating the probe molecule fluorescein isothiocyanate into the micromotor system,we successfully construct a micromotor based HCl or NH3 gas sensor.The autonomous micromotor exhibits a much shorter response time compared to the static one.Furthermore,since the whole structure is based on biopolymer,it is able to be degraded in solution,which may not cause the environmental pollution.5.In order to solve the biocompatibility of the fuel/environment of nano/micormachine,we design a fuel-free and metal-free nano/micromachine,which is based on polymers,i.e.poly(3-hexylthiophene-2,5-diyl)(P3HT).There are two categories of micromachines,i.e.micromotors and micropumps,which are generally considered as two different devices and they do not coexist.Unlike the conventional micromotors or micropumps,the current light-powered micromachine is capable of achieving the functions from both of them,i.e.moving and pumping at the same time.We thus believe the current work may not only bridge the gap between the micromotors and micropumps but also provides useful insight for the design of micromachines with novel motion behaviors.