Preparation And Properties Of Color-changing Seaweed Fibe

With the rapid development of science and technology,the application fields of intelligent color-changing materials are gradually widened.As a renewable green resource,seaweed fiber still has some gaps in the intelligent application.Therefore,this experiment is based on sodium alginate（SA）and calcium alginate fiber（Ca-Alg）,using wet spinning and dyeing process,and introducing photochromic materials,electrochromic materials and p H-chromic materials to give a series of color-changing properties to seaweed fiber.The intelligent extension of seaweed fibers by combining various color-changing techniques is mainly studied in the following aspects.Firstly,the preparation of photochromic alginate fiber（WO₃@Ca-Alg）and its related properties were studied in this experiment.Through literature review,a variety of photochromic materials were comprehensively compared and a small range of experimental studies were conducted.Finally,nano tungsten trioxide was selected as the photochromic material.The photochromic alginate fibers were prepared with sodium alginate and nano-tungsten trioxide as spinning solution by laboratory wet spinning equipment.By exploring the concentration of sodium alginate,concentration of nano tungsten trioxide,crosslinking time and temperature on WO₃@Ca-Alg color performance,fracture strength and flame retardant properties,and determine the best process conditions.Through the analysis of the experimental data,the prepared WO₃@Ca-Alg has improved the performance of flame retardant,salt resistance and fracture strength compared with calcium alginate fiber.At the same time,the changing time of WO₃@Ca-Alg is 30 min,the time of color fading from blue to white is 64 h,and after 15 times of illumination,The discoloration and fading efficiency of the fibers did not change obviously.Finally,it is determined that the best process for preparing photochromic seaweed fiber is:The mass fraction of sodium alginate was 7 wt%,the mass fraction of tungsten trioxide nanoparticle mixture was 10 wt%,the mass ratio of the mixture to glycerol was 1:1,the mass fraction of Na₂B₄O₇ was 1.2 wt%,the mass fraction of coagulation bath and stretching bath was 4wt%,the temperature of coagulation bath and stretching bath was 25℃,and the crosslinking time was 24 h.Secondly,this experiment studied the preparation and performance of electrochromic seaweed fiber（Ele@Ca-Alg）.By Ag⁺replacement method,conductive seaweed fiber was prepared and its conductive ability was tested.By adjusting the ratio and reaction time several times,the optimal result is selected.Tungsten oxide nanosheets with amorphous structure were prepared by alcoholysis.Tungsten oxide nanosheets were coated on electrically conductive seaweed fibers by spraying.Tungsten oxide color-changing electrode was prepared as the working electrode.The electrode is then coated with a gel electrolyte layer,which is added to the opposite electrode to form electrochromic seaweed fibers.The e electrical properties of electrochromic seaweed fiber,such as response time and recycling,were tested.Finally,the best technology is determined as follows:（1）Preparation of conductive seaweed fiber:Ag NO₃ solution concentration is 0.1 mol/L,dimethylamine borane solution mass fraction is 0.05 wt%,heating temperature is45℃.The conductive fiber has a strong electrical conductivity and a resistance of 1.75Ω/cm.（2）Preparation of tungsten oxide discoloring electrode:the concentration of tungsten trioxide is 30mg/m L,the volume ratio of poly（3,4-ethylenedioxythiophene）/poly（styrenesulfonate）（PEDOT:PSS）and anhydrous ethanol is 1:2,coating times are 5times,drying temperature is 80℃.（3）Preparation of poly（vinylidene fluoride-co-hexafluoropropylene）（PVDF:HFP）based gel electrolyte:mass fraction of PVDF:HFP was 2 wt%.Finally,this experiment investigated the preparation of p H-changing seaweed fiber（p H@Ca-Alg）and fabric as well as the properties.Alizarin was chosen as the color-changing material and extracted from Alizarin using different extraction methods,and the extracted alizarin was tested by UV-Vis absorption spectroscopy.The calcium alginate fiber and algal fiber fabrics were dyed by dyeing process.The coloring characteristics under acid and alkaline conditions were determined by studying the staining rate,K/S ratio and color fastness.It was found that the color of the extracts obtained varied due to the differences in the solubilization components of various extractants on alizarin.In a wide environmental range of p H 2.0-11.0,alizarin-dyed seaweed fibers and textiles could exhibit acid yellow alkali red color.The results showed that the p H-variant dyed fabrics treated with poly dimethyl diallyl ammonium chloride（PDMDAAc）were well dyed.The color changes were more significant in the color gamut of different p H values.Although the color change was not very satisfactory,there was still a relatively significant color change.p H color-changing seaweed fiber fabric achieved dry and wet rubbing fastness of grade 4,which met the performance requirements of the fabric.