Preparation And Application Of Beta-chitin Nanofibers

With the development of society,the consumption of resources is increasing.In the face of the increasingly serious energy crisis,more and more researchers have turned to renewable biological resources.Chitin is a natural biopolymer,according to the different ways of molecular chain arrangement,they are divided into three types: alpha crystal,beta crystal and gamma crystal.Compared with cellulose,chitin has many advantages,such as biocompatibility,biodegradability,non-toxic and low resistance to immunity.It has great application prospect in cosmetics,medicine and biological tissue engineering.Chitin nanofibers,besides possess the advantages of chitin itself,but also have the advantages of stable existence in water dispersions,high length to diameter ratio and high specific surface area.As reinforced filler,chitin nanofibers can effectively improve the strength of the matrix,and have great potential in the application of composite materials.The content of chitin in squid bone is about 20%,as a fishery waste,it is a neglected renewable biological resource.In addition,there are few methods to prepare carboxyl chitin fibers,and the carboxylation of chitin nanofibers can be stable under alkaline conditions and can enlarge its application scopes.Therefore,this paper mainly studies the preparation of carboxyl chitin nanofibers from squid bone and related applications.In the first part,we use purified squid pens as raw materials and then treated with ammonium persulfate solution,which can oxidize the active C6 primary alcohol on the chitin molecular chain to carboxyl group,and then ultrasonic under the alkaline condition,we can get the water dispersions of the carboxylation beta-chitin nanofibers with a diameter of 3-4 nanometers,and the length can reach the micron level.In the experiment,we control ammonium persulfate processing time as a variable.Then the carboxylated chitin nanofibers were prepared into aerogel,and the aerogel had irregular macroporous structure.In the second part,we tried to use ammonium persulfate directly to treat the squid pens,the purification step will be omitted and the experimental operation can be simplified,and then ultrasonic under the basic condition,we can get the water dispersions of the carboxyl beta-chitin nanofibers with a diameter of 2-4 nanometers and the length in the micron.Then the carboxylated chitin nanofibers were prepared into hydrogel,and the obtained hydrogel had high transparency and high strength.At the same time,we can also inject the microgel of carboxylated chitin nanofibers dispersion into arbitrary shape,and then in the atmosphere of acetic acid,we can get the intact hydrogel in the original shape.In the third part,we use purified squid pens as the raw materials,and then treated with hydrogen peroxide solution,which can oxidize the active C6 primary alcohol on the chitin molecular chain into carboxyl group,and then ultrasonic under the alkaline condition,we can get the water dispersions of the carboxylation beta-chitin nanofibers with a diameter of 3-12 nanometers and the length can reach the micron level.In the experiment,we control the temperatures of hydrogen peroxide treatment as variables.Then we will obtain transparent film which produced from the carboxyl of chitin nanofibers dispersion by vacuum filtration,and the performances have been characterized.