Preparation And Properties Of Eco-friendly And Durable Polylactic Acid Superhydrophobic Materials

In recent years,the study of wettability has attracted the attention of more and more researchers.The wettability refers to the important characteristics inherent in the solid surface.When the proper surface structure and composition are constructed,new materials with special wettability can be prepared.Superhydrophobic material is one of the special wettability materials that pay close attention to.The superhydrophobic surface is a surface that is repellent to water.The contact angle of water droplets on the surface is greater than 150°,and the surface has excellent self-cleaning,antifouling,and antifouling properties.Anti-icing and drag reduction performance.If the superhydrophobicity of the solid surface can be well controlled,it will have extremely high research significance and economic value for both basic research and application development.However,the current preparation of superhydrophobic materials has shortcomings such as high cost,high equipment requirements,complex equipment processes,poor mechanical durability,and inability to prepare large areas,which severely hinder their wide application.In addition,most of the current superhydrophobic materials are difficult to degrade or slowly degrade under natural conditions,and are extremely easy to be contaminated during use,resulting in a low repeated use rate and making them new pollutants.In response to these shortcomings,this article uses a time-saving and labor-saving solvent evaporation-induced phase separation method based on a large number of literature investigations to design and prepare a super-hydrophobic material with environment-friendly polymer poly(L-lactic acid)(PLLA)as the matrix,low cost,simple process and good durability,and systematically studied and analyzed the properties of the prepared material.The main research content of this paper can be summarized as follows:(1)By adjusting the preparation parameters of PLLA content,drying temperature,poor solvent type,good solvent type and other preparation parameters,a PLLA hydrophobic film with fish-scale micro/nano structure morphology(water contact angle is 138.6°)is prepared.After obtaining the best super-hydrophobic performance parameters,the PLLA film can achieve super-hydrophobic performance(167.1°)by adding hydrophobic nano-silica.The film has good oil-water separation performance,can quickly absorb the oil layer,while repelling water,and can still maintain the original shape well,and has great potential as an environmentally friendly oil-water separation material.(2)The hydrophilic cellulose was modified to hydrophobicity using dodecyltrimethoxysilane,and then the silanized cellulose(GCNC)was mixed with PLLA to prepare a superhydrophobic film.By adjusting the quality of GCNC,a film surface with a controllable network fiber structure can be realized,and the prepared film exhibits excellent superhydrophobicity(155.6°)and high adhesion.The film has good chemical stability,and can still maintain super-hydrophobic properties after immersed in solution with pH of 1,3,5,7,9,11,and 13.After the modification,the crystallinity of the film is greatly improved,and the mechanical properties of the film are further improved,and it can carry about 11 times of its own weight on the water surface,which has a good effect of increasing buoyancy.Because the film has excellent superhydrophobicity and high adhesion,it can be well used in the fields of lossless transportation of droplets,hydrophobic under oil,and super-slip surfaces.(3)Using a dual strategy,the D-LA molecular chain and the silane chain were simultaneously grafted to cellulose,and the hydroxyl groups on the surface of the cellulose were used to initiate ring-opening polymerization and silanization modification of the polyester to obtain the poly(D-lactic acid)/silanized cellulose(PDLA/GCNC).Subsequently,the superhydrophobic film was prepared by adjusting the quality of PDLA/GCNC and nano-silica by mixing,and the prepared film showed excellent superhydrophobicity(160.2°).Due to the generation of three-dimensional complex crystals,the mechanical properties of the film are greatly improved,and the ultimate tensile strength and elongation at break are greatly improved.The film has excellent surface stability,and the membrane is still superhydrophobicity after immersed in different pH solution or irradiated under 1 kW UV lamp.Due to the extremely low adhesion of the film to water droplets,the film has excellent antifouling and self-cleaning properties.In addition,the film has good degradability and can be used as a leading green and environmentally friendly biological material to replace traditional petroleum-based polymers and has the broadest development prospects.