Preparation Of Poly (Lactic Acid) Porous Material And Its Application In Oil-Water Separation

With the continuous development of ocean transportation and industrialization,oil leakage from ships and pollution by industrial organic solvents have become increasingly prominent problems,which not only hinder the development of social economy,but also damage the global ecological environment.Traditional oil-water separation methods are inefficient,costly and unstable,which forces people to search for better oil-water separation methods.Based on the study of the special wetting properties of plants and animals in nature,such as lotus leaf,water strider and rose,a new type of materials which can selectively separate oil and water were prepared.However,these materials had some problems,such as undegradable raw materials and complicated preparation process.In this paper,degradable and environmentally friendly polylactic acid(PLA)was used as the research object,and the PLA porous material with special wetness was obtained by water-assisted thermally induced phase separation method,and its application in oil-water separation was explored.Specific research contents are as follows:(1)The superhydrophobic PLA foam and film with different internal microstructure were prepared by changing the mold shape by water-assisted thermally induced phase separation.It is found that PLA foam with a certain amount of(4 m L)deionized water can reach 151°contact angle after stripping by adhesive tape,the maximum saturation adsorption capacity of oil is 31.5 g/g,and the separation efficiency of oil and water is high(98%).The PLA film with 4 m L of deionized water has a water contact angle of 158°,and which can absorb 11-27 times of its own weight of oil or organic solvents.(2)Based on Flory-Huggins theory,micron-scale PLA porous microspheres were prepared by adjusting the content of deionized water in the system.At the same time,the PLA microspheres modified superhydrophobic non-woven fabric(water contact angle is 152°)was obtained by dip-coating method,which was used for self-cleaning and oil-water separation.For example,the modified nonwoven fabric maintains 98%efficiency over 10 oil-water separation cycles with solvent fluxes of more than 20 m~3m~-2h-1.(3)In order to solve the problem of poor physical properties(low melting point and mechanical properties)of pure PLA porous material,superhydrophobic stereocomplex-PLA(Sc-PLA)porous foam with high melting point(220?)was prepared by introducing dextral polylactic acid(PDLA)into left-handed polylactic acid(PLLA).It was found that the amount of deionized water could affect the content of Sc crystal and homogeneous crystal(Hc)in Sc-PLA foam.When a certain amount(2 m L)of deionized water is added,the content of Sc crystals in the foam reaches the maximum24%,and the water contact angle reaches 152°.Superhydrophobic Sc-PLA foams show excellent self-cleaning properties and high oil adsorption capacity.In addition,Sc-PLA foams exhibit good thermal insulation and mechanical properties.