The Research Of Water-borne Polymer/graphene Oxide Nanocomposites

With the increasing awareness of environmental protection and safety,the development of water-borne polymers with low volatile organic compounds VOCs and high performance has attracted more and more attention.However,the shortcomings of water-borne polymers,such as inadequate mechanical properties,water resistance and barrier properties,limit their applications in the field of high-performance materials.Graphene oxide（GO）has great potential in the field of modification of water-borne polymers because of the good hydrophilic properties,modifiers,excellent mechanical properties,high thermal stability,excellent barrier properties and other characteristics.But how to control the uniform dispersion and directional arrangement of GO in water-borne polymer coating materials is the key to improve the comprehensive properties of water-borne polymer/graphene oxide nanocomposites.Based on the above statement,different modifiers were selected to prepare modified graphene oxide,and water-borne polymer/modified GO nanocomposites were prepared with polyvinyl alcohol,water-borne epoxy and water-borne polyurethane.Specific studies are as follows:1.The modified graphene oxide（SGO）was prepared by surface modification of GO using sulfamate compound（AS）,and PVA/SGO nanocomposite dispersion,film and coating were obtained by compounding with PVA.Attenuated total reflection flourier transformed infrared spectroscopy（ATR-FTIR）,X-ray diffraction（XRD）and Thermogravimetric analyzer（TGA）showed that AS was successfully grafted between GO layers,and the graft rate of AS was 12.34%.Scanning electron microscopy（SEM）showed that SGO was uniformly dispersed in PVA.The tensile test showed that when the SGO content was 3 wt%,the tensile strength of PVA/SGO nanocomposite film increased to 70.5MPa,and the elongation at break decreased slightly to 179.5%.The addition of SGO could effectively improve the barrier effect of PVA/SGO nanocomposite coating.When the SGO content reached 80%,the water vapor and oxygen transmittance were reduced to the lowest,respectively 6.99 g·cm^-2·day^-1 and 0.33 cm³·m^-2·day^-1·atm^-1.At the same time,the oxygen transmittance could also remain relatively stable under high humidity（50%,70%,90%）.2.Using polyether amine（PEA）to surface modify GO which was activated by carboxyl group by 1-ethyl-（3-dimethylaminopropyl）carbodiimide hydrochloride（EDC）/N-hydroxysuccinimide compound（NHS）to prepare modified graphene oxide（AGO）,and blending with water-borne epoxy emulsion（WEP）and water-borne amine curing agent to prepare WEP/AGO nanocomposite emulsion,film and coating.ATR-FTIR and XRD tests showed that PEA was successfully grafted on GO surface and the grafting rate was 6.2%.SEM showed that AGO was uniformly dispersed in WEP/AGO nanocomposite films.Tensile test showed that the addition of AGO enhanced and toughened the WEP/AGO nanocomposite film.When the content of AGO was 1.0 wt%,the tensile strength of the WEP/AGO nanocomposite film increased to the maximum of 60.83 MPa,and the elongation at break increased to 4.5%.Electrochemical and salt spray performance tests showed that the impedance value of WEP/AGO nanocomposite coating at low frequency is more than 10⁸Ωwithin 30 days,and there were no obvious pitting diffusion and infiltration of corrosive medium on its surface.Therefore,it had better corrosion resistance compared with WEP/GO nanocomposite coating.3.The modified graphene oxide（NGO）was obtained by surface modification of GO which was activated by EDC/NHS using the self-made amino-hydrophilic polyurethane（NHPU）.The WPU/NRGO nanocomposite emulsion and coating were obtained by in situ emulsification with the self-made water-borne polyurethane（WPU）and reduction with hydrazine hydrate.NGO could disperse evenly in water,acetone,DMF,and THF organic solvents.At different concentrations,NGO showed four different dispersion states:water dispersion,viscous,gelatinous,and"silly putty".ATR-FTIR,XRD tests showed that NHPU was successfully grafted onto GO surface and the graft rate was 4.5%.SEM showed that NGO was evenly dispersed in WPU/NGO nanocomposite films.Tensile tests showed that when the NGO content reached 2 wt%,the maximum tensile strength reached 43.1 MPa and the strain reached 907.9%.The electrical conductivity of 4 wt%WPU/NRGO nanocomposite coating reached 2.05×10^-5 S/cm,which met the antistatic standard and had high light transmittance.