Physical Methods To Improve The Electromagnetic Response Of Cellulose Nanocrystals

Cellulose nanocrystals are a kind of renewable and degradable biomass nanomaterials,with high aspect ratio,good transparency,large specific surface area,high mechanical strength and biocompatibility.Cellulose nanocrystals are widely sourced in nature,mainly from higher plants such as trees.There are also many methods for extracting CNC from cellulose raw materials,such as sulfuric acid hydrolysis,TEMPO oxidation,etc.Cellulose nanocrystals can be used as a reinforcing filler in polymer materials or as a matrix material for some functional composite materials.In addition,when the concentration of the cellulose nanocrystal suspension is above the threshold concentration,it can form CNC cholesteric liquid crystal,which can be dried into a CNC color film.The orientation of the CNC is very important in practical applications.The external electric field or magnetic field can be used to control the orientation of the nanorods in the CNC,but it requires a strong electric or magnetic field to be oriented,which greatly limits the orientation control of the CNC.Therefore,we need to improve the responsiveness of CNC in electric or magnetic fields from different aspects.In this paper,the cellulose nanocrystal suspension was prepared by sulfuric acid hydrolysis method.It was found that the surface of the CNC prepared by sulfuric acid contained negatively charged sulfonate,and the nanorods had good dispersion due to charge repulsion.At the same time,the method for preparing cellulose nanocrystals belongs to the typical cellulose I crystal form,which has the characteristics of high aspect ratio,large specific surface area,and abundant hydroxyl groups on the surface.It has great application prospects as a matrix of nanocomposites.In order to improve the responsiveness of cellulose nanocrystals in electric or magnetic fields,we start with the preparation method.We used potassium ferrate to prepare cellulose nanocrystals and compared with CNC prepared by TEMPO oxidation method.The former Fe3+ introduced in the reaction forms a complex with the carboxyl groups on the surface of the CNC.Its dispersibility is poor,and there is a certain degree of aggregation,which makes it impossible to perform CNC orientation tests in electric or magnetic fields.Secondly,we attached magnetic peroxosilicate[{Cu(2,2-bpy)} {Cu(IN)2}{Mo4O12(OH)2}]to the surface of cellulose nanocrystals to improve the electromagnetic response of CNC.We successfully prepared a magnetic CNC with a magnetic salt attached by hydrothermal treatment.It is dispersed and stable in an aqueous solution and can be oriented in a 1T magnetic field or a good orientation along an electric field at a frequency of 2 x 105 Hz and a voltage of 1200 V/cm.It improves the orientation ability of CNC in electric field or magnetic field.