The Preparation of Superhydrophilic Surface Based on the Zwitterionic Polymer and Its Application

Author:Liang Bang

Supervisor:su chao zuo


Degree Year:2019





In recent years,the surperhydrophilic surfaces have attracted great attention due to the broad application.The references reported to achieve superhydrophilic surfaces are by either constructing surface structure on hydrophilic surface or modification of hydrophilic material on surface structure.However,the preparation of micro and nano structures with specific topography is usually complicated,time-consuming procedure and the complex instrumentation.So the superhydrophilic surfaces without concerning surface structures are more practical and desirable.Zwitterionic polymer with the strong water-binding ability,when grafted on the surface,presents the superhydrophility in theory.However,the "anti-polyelectrolyte"of the zwitterionic polymer due to the electrostatic and dipole-dipole effect,worse the water-binding ability and increase the hydrophobicity of the surface.Therefore,we adjust the factors of the interactions of zwitterionic polymer grafted surface,such as thickness and ionic strength to obtain the superhydrophilicity.In this thesis,we firstly prepared the polyzwitterionic surface on the silicon with by ATRP with "graft from" method.We achieved the superhydrophilic surface by adjusting the thickness of the polyzwitterion brushes.Polyzwitterion can be explored as icephobic materials because they are hygroscopic and can support a self-lubricating liquid layer that does not freeze at relatively low temperatures.Then,we constructed the zwitterionic superhydrophilic surface on various substrates by using the sticky catechol chain end and dopamine with "graft to" method with the change of the ionic strength.Meanwhile,we found the zwitterionic polymer superhydrophilic surface can be useful for antifouling and oil/water separation.1.We firstly fastened the initiator onto the silicon substrate and then obtained the polyzwitterion brushes by SI-ATRP.Adjusting the thickness of the polymer brushes,we achieved the superhydrophilic surface.In the experiments of anti-icing,we found zwitterionic brushes can interact with water molecules and form a dense and thick quasi liquid water layer at the surface and be stable under low temperature,attributing to decrease the ice-adhesion.After further research,we found the zwitterionic polymer have strongest ability to interact with water molecules than typical polyelectrolyte and can decrease the ice adhesion dramatically.2.Using the wide adhesion of the catechol to the various substrates,we conveniently grafted the zwitterionic polymer on the substrates.Firstly,we synthesized the sticky catechol chain end initiator and further obtained the catechol chain end zwitterionic polymer by ARGET-ATRP.Then we deposited the zwitterionic polymer on the various substrates with the dopamine and obtained the superhydrophilc surfaces with the change of ionic strength.We used the membranes with the deposited zwitterionic polymer for oil/water separation and achieved the excellent effect and also found the membrane have the excellent antifouling property due to the strong water-binding ability,which can increase the stability of the membrane.3.We synthesized zwitterionic monomer with the strong "anti-polyelectrolyte effect".Then using the reduction of dopamine,we in-situ synthesized the AgNPs on the surface.Next,the initiator was fastened to graft from the polyzwitterion brushes.Combine the bacteriocidal capability and the salt-responsive behavior of polyzwitterion brushes,we could kill and release the bacterial on the surface.Based on the understanding of the above works,we found the strong the electrostatic interaction in the zwitterionic polymer systems have a great effect on the material properties.As the interactions are reversible,we considerate the zwitterionic polymer into the self-healing hydrogel and did the next work.4.We prepared the nanocomposte hydrogel by copolymerization of silica nanoparticle,zwitterionic monomer and HEMA monomer.We adjusted the ratio of zwitterionic monomer and HEMA and obtained the hydrogel with excellent mechanical and self-healing properties.Meanwhile,the hydrogel also show excellent antifogging,anti-icing and antifouling properties due to the strong water-binding ability of zwitterionic groups.