Study On Superhydrophobic Modification Of Textiles By Phenolic Compounds And Metal Ions And Its Application

At present,the research and application of functional textiles have attracted widespread attention,such as flame retardant,hydrophobic,flexible conductive fabrics,etc.Among them,superhydrophobic textiles have broad application prospects in medical protection,oil-water separation,outdoor clothing and other fields.Therefore,research on superhydrophobic surfaces and superhydrophobic textiles is increasing.Some phenolic compounds have been reported to be used for superhydrophobic surface modification of textiles.However,for the textile industry,there are still many problems to be solved and improved in the modification technology of superhydrophobic textiles based on phenolic compounds reported in the literature,such as high pollution of modified reagents,use of organic solvents in large quantities,complex process and high cost of raw materials,and many methods are not suitable for large-scale production at present.Therefore,this paper systematically studies the hydrophobic modification of various textiles by dopamine and other phenolic compounds without organic solvent,and discusses the rapid construction of superhydrophobic structure and the formation mechanism of some structures,so as to provide theoretical and practical basis for the application of phenolic compounds in superhydrophobic modification of textiles.The main research contents are as follows:Firstly,the optimal reaction conditions of laccase were studied:acetic acid buffer was selected as the buffer to adjust the pH value of laccase reaction system,the optimal concentration was 0.1mol/l,and laccase showed the highest activity at pH=3.5 and temperature of 55℃.When laccase was used to catalyze the self-polymerization of dopamine in acid condition,the dyeing effect of 3h in acid condition to silk fabric was better than 24h in alkaline environment,and the uniformity was also better.And through molecular simulation analysis,the dopamine polymer was easy to bind to the amorphous region of silk fibroin,the dopamine oligomer and the amino acid of silk fibroin could form hydrogen bonds and π-πstacking interaction.Dopamine oligomers could form intermolecular and intramolecular hydrogen bonds through amino and hydroxyl groups.Dopamine oligomers would aggregate in the process of adsorption to silk fibroin,and adsorb to the surface of silk fibroin in the form of aggregates.The polydopamine loaded on the surface of the silk fiber was deposited with Ag⁺,Cu²⁺,Fe³⁺,Ni²⁺ and Fe²⁺ respectively,which can form particles with different shapes on the surface of the silk fiber.Most of the modified silk fabrics were hydrophobic fabrics,in which the ultra-high contact angle with Fe²⁺ modified fabric was more than 160°.In addition,the particles formed by the above-mentioned polydopamine with Ag⁺ and Cu²⁺ were the corresponding zero-valent nanoparticles and their oxides,the particles formed with Ni²⁺ were only amorphous hybrid particles,and the particles formed with Fe³⁺ were the mineral α-FeOOH.Besides,some plant-derived polyphenol dyed silk fabrics were also used to deposit the above metal ions,among which the contact angles of polyphenol modified silk fabrics after reaction with Fe²⁺were all higher than 145°,and the hydrophobic effect was the best,so Fe²⁺was selected as the target metal ions.In the third chapter of this paper,laccase catalyzed a variety of phenolic compounds to modify silk fabrics,which were then reacted with ferrous solution and aged.It was found that hybrids of iron and polyphenols having different shapes were grown on the surface of the silk fabric.The contact angle of dopamine/iron modified silk fabric was as high as 165°,and its surface was covered with dense and uniform needle-shaped γ-FeOOH nanorods,which could build rough structure on the surface of silk fibers.The dopamine/iron modified silk fabric had excellent superhydrophobic,flame-retardant and ultraviolet protection properties,and its preparation process was simple and environmentally friendly.The dopamine/iron modified silk fabric had good abrasion resistance and washing resistance.During the combustion performance test of dopamine/Fe²⁺ modified silk fabrics,the FeOOH and polydopamine greatly promoted the formation of a dense carbon layer on the fiber surface,and the flame retardant mechanism was mainly derived from the flame retardancy of the coalesced phase.In addition,through comparative analysis of the electrostatic potentials of representative ferulic acid,caffeic acid,dopamine and their oligomers,the formation mechanism of different of Fe and polyphenol hybrids on the fiber surface was preliminary discussed.More than half of the molecular surface electrostatic potentials of ferulic acid,caffeic acid and their oligomers are neutral,which leads to their poor water solubility and the formation of hydrophobic spheres.Due to the negative electrostatic potential around the linking groups formed by β-β or β-5 reactions,the linking groups can form coordination with the Fe²⁺,and then the Fe²⁺ performs the mineralization and the deposition.In the oxidative polymerization of dopamine,there remains a lot of hydroxyl groups.There are more regions with larger absolute value of electrostatic potential in dopamine and its oligomers,and the water solubilities of them are better.The polydopamine molecules can aggregate and form hydrogen bonds by hydroxyl groups and amino Groups.Because of their fine water solubility,they can stretch freely in water and form rod-like clusters.The Fe²⁺can react with the rod-like polydopamine clusters via the coordination bonds and form nanorods after the mineralization and the depositionIn the fourth chapter of this paper,the laccase catalyzed hydrophobic modification of cotton fabric by various phenolic compounds and Fe²⁺ was investigated,such as tannic acid,ferulic acid,dopamine and caffeic acid etc.It is found that in addition to ferulic acid and dopamine modified cotton fabrics,the contact angle of other phenolic compounds with Fe²⁺modified cotton fabric was more than 150°,and the contact angle of caffeic acid/Fe²⁺ cotton fabric was the highest,reaching 159°.Therefore,this chapter focused on the superhydrophobic modification of cotton fabric by caffeic acid/Fe²⁺.Compared with the original cotton fabric,the surface of superhydrophobic cotton fabric was covered by a composite deposition film containing caffeic acid/iron hybrid particles,and the root mean square value of the surface roughness was about 93.7nm.Before and after modification,the mechanical properties of caffeic acid/iron cotton fabric had no obvious change.In addition,the superhydrophobic cotton fabric can withstand extreme conditions such as high temperature,extreme cold,and UV radiation,and had good abrasion resistance,self-cleaning and oil-water separation performance.This method of constructing deposition films and superhydrophobic surfaces on the substrate was versatile and efficient.Caffeic acid/iron could be deposited on many different substrates to build highly hydrophobic surfaces,such as silk fabric,PU sponge and other substratesThe fifth chapter of this paper studied the hydrophobic modification of cotton fabric by different phenolic compounds and Fe²⁺ respectively under the condition of no laccase catalysis.It was found that tea polyphenols and Fe²⁺ had the best effect on one-step modification of cotton fabrics.The surface of tea polyphenol/iron cotton fabric was covered with a layer of dense 3D micro-particles,and its roughness root mean square value was about 70.9 nm.Tea polyphenol/Fe²⁺cotton fabric had excellent superhydrophobicity,its water contact angle was about 162°,rolling angle was about 15°,and tea polyphenol/Fe²⁺ superhydrophobic cotton fabric had good washability and excellent wear resistance.In addition,tea polyphenol/Fe²⁺cotton fabric also had good self-cleaning performance and high-efficiency separation performance for a variety of oil-water mixtures,even under the adverse conditions such as HCl（pH=1）,NaOH（pH=12）,hot water（80℃）.This preparation method of superhydrophobic textiles had a certain degree of universality,which could modify silk fabrics into hydrophobic fabrics,in which the contact angle of wool fabric was more than 150°,the contact angle of polyester fabric was more than 160°,and it had excellent superhydrophobic properties.