Preparation Of Cellulose Nanocrystals And Their Applications

Cellulose nanocrystals are nanomaterials derived from cellulose,and they have a broad application,such as:preparation of gel composites;preparation of fine chemicals and conductive material matrix.Cellulose nanocrystals are mainly prepared by acid hydrolysis and TEMPO oxidation.The above methods have the negative effect on the environment due to the use of large amounts of acid-alkali or toxic chemicals;at the same time,the former has a low yield and takes a long time.In order to solve the problems of low production rate and long time consuming of the existing cellulose nanocrystals preparation method,we have developed a new method based on physical high-energy irradiation oxidation to separate and prepare cellulose nanocrystals by y-valerolactone-water cosolvent system method.The cellulose nanocrystals yield of this method is 86.88%,which is higher than the traditional preparation method;the preparation process is efficient and rapid;at the same time,the cellulose nanocrystals can form a liquid crystal phase at a very low concentration of 0.5 wt%.For the subsequent efficient preparation of cellulose nanocrystals and optical materials provide the possibility.The main research results are as follows:1.Using eucalyptus as raw material,y-irradiation pretreatment auxiliary solvent method to separate bulk cellulose to obtain cellulose nanocrystals.The yield was 86.88%,increased by 60.22%and 20.91%respectively compared with the sulfuric acid-catalyzed solvent method.Cellulose nanocrystals were characterized by SEM,TEM,DLS,Zeta,FTIR and XPS.2.Polyvinyl alcohol was dissolved in dimethyl sulfoxide,0.5 wt%of cellulose nanocrystals were added,and a retractable hydrogel was prepared by a freeze-casting method.At the same time,carbon nitride quantum dots were added to further prepare a cellulose nanocrystals composite hydrogel for detecting metal Fe3+.