| Supramolecular polymers based on the combination of quadruple hydrogen bonds have unique dynamic reversibility and environmental(heat,light,p H,etc.)responsiveness,and can be used for the design of intelligent functional materials such as self-healing.In recent years,the 2-ureido-4[1H]-pyrimidinone(UPy)systems,a kind of quadruple hydrogen bonds system combined in the form of AADD-DDAA,have attracted much attention due to their extremely high dimerization constant and stability.However,the current related researches mainly rely on the organic solvent systems,and the VOCs(volatile organic compounds)released during processing will cause environmental pollution;in addition,the introduction position of UPy motifs is mostly at the end groups of the molecular chain,which makes the self-assembly of the polymer based on the quadruple hydrogen bonds of the terminal group linearly cross-link,with the limited strength and the assemble process would be interrupted easily.Regarding the issues above,this paper uses polyurethane,a polymer material with extremely high application value can be easy modified and its raw materials are easily available,to design a supramolecular waterborne polyurethane with quadruple hydrogen bonds motifs in main chain.Firstly,UPy functionalized monomer(HMA)was synthesized by one-step reaction using guanidine carbonate andα-acetyl-γ-butyrolactone as raw materials.Then,three groups of supramolecular waterborne polyurethane dispersions with quadruple hydrogen bonds motifs in main chain was prepared with the poly(1,4-buthylene-neopentylene adipate glycol)(PBNA)as the soft segment,isophorone diisocyanate(IPDI),HMA,hydrophilic monomer 2,2-dimethylolpropionic acid(DMPA),isophoronediamine(IPDA),triethylamine(TEA)and blocking agent monoethanolamine(MEA)as the hard segment.UPy functional monomer content(HMAC)and total hardness content(HSC)and hydrophilic monomer content(HGC)are the variables.The test of Proton nuclear magnetic resonance spectra(~1H NMR),Fourier Transform Infrared spectra(FTIR)and Gel permeation chromatography(GPC)confirmed that the the UPy functionalized monomers and 4H-WPU dispersion prepared in the experiment were the target products.Explored the effect of HMAC,HSC and HGC on the performance of emulsion through stability test,particle size and viscosity test,etc.The results showed that the prepared 4H-WPU dispersions have good stability.The particle size of the dispersion increased with the increase of HMAC or HSC,and decreased with the increase of HGC.The trend of viscosity is inversely proportional to the trend of particle size.The results of Transmission electron microscope(TEM)test showed that 4H-WPU particles were roughly spherical and the particle size distribution is normally distributed.The film properties of 4H-WPU were explored by differential scanning calorimetry(DSC),tensile test,self-healing test and water resistance test.The results of DSC test showed that both of the increase of HMAC and HSC would increase the glass transition temperature T_g of 4H-WPU film.The results of tensile test showed that the 4H-WPU film has excellent mechanical properties,and the tensile strength increased with the rise of HMAC,which can be up to 10times of the blank sample,and the change in elongation is opposite with strength.The results of self-healing test showed that 4H-WPU has excellent self-healing performance,the fastest healing time is 2.5h,and the repair rate of mechanical properties can reach more than 90%.The results of water resistance test showed that the water absorption rate of all 4H-WPU films was below 10%,which means the 4H-WPU film has good water resistance. |
