Study On Waterborne Polyurethane Modified With Functionalized Graphene

Waterborne polyurethane(WPU),as a new kind of water-based resin,not only meets low-carbon and environment-friendly demands proposed currently,but also attracts more and more attention from scientific researchers,industry and customers due to its couples of advantages in terms of non-toxic matrix,low emission of VOCs,environmental friendly base and low consumption since it emerged.While compared with traditional polyurethane,pure WPU matrix shows a series of drawbacks including poor resistant to water and low mechanical strength.Therefore,it is meaningful and valuable for developing novel WPU to solve above problems and find potential application.Given that graphene oxide nanosheets are with excellent properties and are easy to be functionalized,some related work can firstly be designed to graft specific groups on their surface due to those easily functionalized oxgen-containing groups on their surface,and then introduce them onto WPU matrix through solution blending or in-situ polymerization,to obtain novel hybrid polymers.Some measurements were used to characterize thermal stability,mechanical strength and hydrophobic behaviours for those hybrid polymers,such as fourier transform infrared spectroscopy(FT-IR),raman spectronmeter(Raman)and X-ray diffraction(XRD),thermal gravimetric analysis(TGA),transmission electron microscopy(TEM),atomic force microscopy(AFM),scanning electron microscopy(SEM)and static contact angle,et al.In conclusion,the main research contents in this paper are as follows:Waterborne polyurethane modified with few-layers graphene oxide: few-layers graphene oxide were firstly fabricated by improved Hummers' method.Based on the advantage of hydrophibic behavior on the surface of graphene oxide and the advantage of few layers that did not agglomerate easily,the water dispersion of few-layers graphene was then physically blended into WPU at a high speed in the process of emusifing to obtain GO/WPU composites.Lastly,some properties of GO/WPU hybrids,such as thermal stability and mechanical strength,were evaluated by corresponding characterization tools.Results indicated that few-layers graphene oxide could stablely disperse into WPU matrix.With 0.20 wt% GO nano-layers added,composites could achieve 24 MPa in strength where pure WPU could only attain 10.00 MPa.Additionally,thermal stability of composites was also improved.Waterborne polyurethane modified with aminopropyltrimethoxysilane functionalized graphene oxide(APTMS-GO): aminopropyltrimethoxysilane,a kind of aminosilane-coupling agents,was used to functionlize graphene oxide to obtain APTMS-GO.Based on the chemical reaction between groups containing active hydrogen in terms of —OH,—COOH and —NH2 on the surface of APTMS-GO nanosheets and —NCO groups on PU chains,APTMS-GO/WPU composites were fabricated by in-situ polymerization.The corresponding physical properties in terms of thermal,mechanical properties of composites were investigated.Results indicated that 0.33 wt% APTMS-GO could reach 28.96 MPa compared with pure WPU.Moreover,Td5,namely initial thermal degradation of composites,was also increased by 34 ?.Waterborne polyurethane modified with octa(aminopropyl)polyhedral oligomeric silsesquioxane(Oap POSS)functionalized graphene oxide: Oap POSS was first covalently grafted onto graphene sheets to obtain a novel nanomaterial,Oap POSS-GO,via amide formation between the amine groups at the eight vertices of POSS and the oxygencontaining groups(e.g.,epoxy and carboxyl groups)of graphene oxide.Then,-NH2 featured on the surface of POSS-modified graphene sheets would react with the —NCO of PU chains or unbonded —NCO by in situ polymerization to fabricate a welldispersed nanocomposites.Some physical properties of the nanocomposites including thermal properties,mechanical properties,and hydrophobicity were investigated.Results revealed that the addition of 0.30 wt% Oap POSS-GO could increase the strength of WPU from 10.13 MPa to 27.80 MPa.In addition,Td5 of 0.50 wt% POSS-GO/WPU was delayed to 288 ?.Likewise,the surface of WPU was changed from smooth into rougher after being filled with Oap POSS-GO.