Studies On Preparation And Properties Of Polyurethane Nanocomposites

Polymer nanocomposite coating with the dual characteristics of the organic component and the inorganic component,retaining the advantages of the polymer and possing the versatility,is one of the most promising fields in current research,which is in accordance with the requirements of current application.Among them,there are two major obstacles in the recombination process between nanomaterials and polymers,such as dispersibility and compatibility.Therefore,how to improve the dispersibility of nanoparticles and enhance the compatibility between nanoparticles and polymers are the challenges that needs to be solved.In this work,polyurethane was used to stabilize nano-ZnO and graphene oxide,which were introduced to UV-curable polyurethane for UV-curable polyurethane/ZnO nanocomposite films and waterborne polyurethane for WPU/graphene nanocomposite films or coatings,respectively.The specific study was summarized as follows:1.Isophorone diisocyanate?IPDI?,polytetramethylene glycol?PTMG,M_n=2000?,dimethylolpropionic acid?DMPA?and hydroxyethyl methacrylate?HEMA?,butanol?CH₃CH₂CH₂CH₂OH?and pentaerythritol triacrylate?PETA?were used as raw materials to synthesize amphiphilic polyurethanes?APU?with different functionalities;Amphiphilic polyurethanes acted as stabilizers and emulsifiers in preparing APU-ZnO by the inverse miniemulsion?one-step?through the strong interaction between the carboxyl groups of amphiphilic polyurethanes and the hydroxyl groups on the ZnO surface;The nanocomposites with UV shielding property were synthesized by the combination of APU-ZnO and UV-cured PUA.The effects of amphiphilic polyurethanes with different functionalities on the morphology,particle size,crystal structure and surface grafting ratio of ZnO particles;APU-Zn O with different functionalities on the nanocomposite films;The mechanical,thermal,anti-ultraviolet and fluorescence properties of the nanocomposites with a series of APU-ZnO were systematically studied.The structure,morphology,comstituent and properties of the prepared PUA/APU-ZnO nanocomposites were investigated by FT-IR,TEM,DLS,XRD,TGA,UV-Vis,DMA,SEM,tensile test and fluorescence properties test;The results showed that changing functionalities of amphiphilic polyurethane could adjust the amount of APU on the surface of nano-Zn O,and the amount of PTMG-HEMA-ZnO was higher,up to 14.27 wt%;Compared with the pure resin,the film containing 0.3 wt%PTMG-HEMA-ZnO possessed better mechanical properties,whose Young's modulus increasing to 1.46 times and tensile strength increasing to 1.49 times;Under the condition of 81%light transmittance,the film had better UV shielding property?UV resistance?and fluorescence properties.2.Grapheneoxide?GO?wasfunctionalizedbycarbodiimide?EDC?and N-hydroxysuccinimide?NHS?to acquire NHS-functionalized GO?NGO?;It was then added to the waterborne polyurethane prepolymer for WPU/graphene nanocomposites.The morphology,structure,and interlayer spacing of GO and NGO and their effects on the mechanicaland thermal properties of nanocomposite films;The effects of different functionalized graphene?NRGO?content on the particle size of nanocomposite emulsions and the thermal,mechanical,and electrical properties of the nanocomposite films were systematically studied.The structure,morphology,composition and properties of the prepared WPU/graphene nanocomposites were investigated by FT-IR,DLS,TEM,AFM,XRD,TGA,DMA,SEM,tensile test and four-probe test;The results showed that the addition of GO and NGO could slightly improve the mechanical properties and thermal stability of WPU;RGO caused the decline of the performance of the nanocomposites;The addition of NRGO enhanced the mechanical,electrical conductivity and thermal stability properties of the nanocomposite films;At the content of 2.6 wt%of NRGO,the best tensile strength of the film reached to 61.2 MPa and the Young's modulus was 86.9 MPa;And the surface conductivity of the composite coating was good;The surface conductivity of coatings was a continuously increasing trend with the addition of NRGO,in which the low content increased exponentially and the high content increased slowly;The highest amount of NRGO reached 30 wt%,corresponding to the electrical conductivity of 3.53×10^-22 S/cm;Therefore,the coating of WPU/graphene could be applied in antistatic and conductive films and coatings.