Synthesis And Characterization Of Anionic / Nonionic Waterborne Polyurethane Containing Functional Side Chain

There are many research works started in the field of waterborne polyurethane(WPU),based on industry specially researches on anionic & cationic waterborne polyurethane but less on non-ionic WPU.Non-ionic WPU emulsion has good acid and alkali resistance,and it can be usedtogether with other types of emulsion without worrying about de-emulsification.So,non-ionic WPU has great application prospect.To improve the synthesis process & technology through the design & composition of polyurethane molecular chain block structure,composition of branched chain,branching or cross linking’s degree and ionic strength also to determine the modified monomers with the optimum ratio.Synthesized non-ionic WPU emulsions have good stability and have good physical properties of films.In addition,a series of polyether,polyester and polyether/polyesterWPU are synthesized by adding hydrophilic nonionic segments(-CH2CH2O-)to the side chain of PU molecules.WPU emulsions are evaluated by viscosity,particle size,interface tension and emulsion stability.The evaluations of WPU films are carried out with acid and alkali resistance,water resistance and static contact angle.Fourier transform infrared spectroscopy(FT-IR)and thermo gravimetric analysis(TG)are used to characterize the structure of WPU.In these ways,the best WPU product is obtained.The result shows thatif other hydrophilic chain extenders are not used,the nonionic hydrophilic chain extender can provide hydrophilicity which can make polyurethane easy to emulsify.However,its film becomes worse.To solve this problem,trace anionic chain extender and a certain degree of crosslinking are introduced to improve film water repellency and feel.The soft monomer containing three reactive groups and capping agent can improve the degree of cross linking of WPU.WPU modified with silicone,then the silicone make’s the film softer and improve its feel.In order to make the WPU films waterproof,hydrophobic long chain alkyl segments are introduced into the side chain of WPU,but which will make the emulsion stability worse.At the same time,the introduction of hydrophilic nonionic chain extender(NE)can reduce the viscosity of waterborne polyurethane system,and produce high solid content of waterborne polyurethane.In this research,a series of waterborne polyurethane emulsions were prepared,and the solid content of the emulsion was up to 51%.