Seaweed-inspired Preparation And Performance Study Of Underwater Superoleophobic Hydrogel

Recently special wettability surface has become one of the research hotspots in materials science, physics, chemistry and other related fields. Underwater superoleophobic materials have aroused widespread concern because of its broad application prospects in anti-fouling, anti-corrosion, water and oil separation, microfluidics, anti-biofouling prospects and other fields. Researchers have prepared a variety of underwater superoleophobic materials through a variety of methods, however, there are problems such as complicated preparation process and poor salt tolerance stability etc. with most of the materials. To put the underwater super oleophobic materials into practice, further research and improvement are needed. The main contents and conclusions of this thesis are as follows:(1) Seaweed a typical marine algae can always keep its surface clean in complex marine environment, what contributes to this phenomenon is its special surface wettability. The analysis of its surface wettability shows that it has amphipathy in the air and has superoleophobic nature underwater. Besides the findings of its structure demonstrates that there are micro-nanometer projections.(2) Sodium alginate is the main component of mucus of seaweed surface, chitosan is derived from arthropods, both of which are broad in sources, non-toxic, and biodegradable. With sodium alginate and chitosan as raw material and layer-by-layer self-assembly can prepare the underwater superoleophobic surface material, whose surface micro-nanometer network structure exists on and of whose surface the contact angle and roll angle with dichloromethane is CA = 152° ± 2°, SCA = 3.5° ± 1° underwater. This kind of underwater superoleophobic surface material gains good stability, frees to the different pH value of the solution and maintains long-term underwater superoleophobic nature in artificial seawater. The degree of light transmission is much higher underwater than dry state, which the light transmission rate will reach 90 % also with a function of preventing biological protein adhesion.(3) Adopting the method of freezing – thawing repeatedly can prepare sodium alginate hydrogel mixed with polyvinyl alcohol. Adjusting the content of polyvinyl alcohol can prepare hydrogel with favorable underwater superoleophobic properties, on whose surface a micro-nanometer scale porous structure exits, the underwater contact angle of oil is up to 152° and the adhesion of oil is very low with 1.5° sliding angle and has performance of resistance to protein adhesion. Besides the mechanical properties of polyvinyl alcohol has been greatly improved mixed with alginate hydrogel.(4) Synthetic organic polymer poly diallyl dimethyl ammonium chloride and polystyrene sulfonate are hydrophilic and omposite hydrogel can be prepared by centrifuging the mixture with ultrahigh speed. There is micro-nanometer scale pore structure on the surface of this kind of hydrogels. Hydrophilic chemical composition and the surface structure qualify the omposite hydrogel with underwater superoleophobic and anti-biofouling properties.