Preparation And Characterization Of Cellulose Nanocrystalline Based On Microfluidic Technology

Cellulose nanocrystalline(CNCs),as a new biomass-based molecule material,has become a research hotspot in many fields.Because of its excellent mechanical and optical properties,CNCs are used in cosmetics,composite materials and other fields.How to prepare and characterize CNCs controllably is of guiding significance for its application.Microfluidic technology has been widely used in biomedicine and chemical reaction because of its high sensitivity,low sample consumption and automation.Combined with CNCs and microfluidic technology,the new preparation and characterization technology of CNCs was studied based on microfluidic chip,and the optimum process conditions were explored.The prepared CNCs were labeled with fluorescence,and then fast characterization was realized on microfluidic chip.Firstly,the flow characteristics of CNCs in microfluidic chips are studied.According to the flow characteristics,a set of microfluidic chips with complete loading reaction platform is designed,including the channel shape design of microfluidic chips,the addition of samples and reaction reagents,the control of reaction fluid flow in the chip,the mixing of samples and reaction reagents,the termination and maximum of the reaction and the collection of CNCs.Using microcrystalline cellulose(MCC)as raw material,CNCs was prepared by acid hydrolysis using designed chips as carriers.According to the yield and particle size of CNCs,the optimum reaction conditions were obtained as follows: sulfuric acid concentration 60%(w/w),reaction temperature 35 ?,hydrolysis reaction time 40 min.Under these conditions,the yield of CNCs was 43.76%.The length and width of CNCs were 204 nm and 20 nm respectively.The prepared CNCs can form a stable transparent suspension in the water dispersion system,and there will be no stratification or precipitation in the long-term storage at room temperature.The prepared CNCs were labeled with fluorescence and characterized by particle tracking velocimetry(PTV).The CNCs flowing in liquid emitted fluorescence after irradiation by a special wavelength light source and were imaged on EMCCD.After imaging,the PC recognized the image according to the algorithm.After recognition,the size and velocity of the PC were calculated.The width of the CNCs prepared by acid hydrolysis method was measured by this method.The length is 200 nm,which is basically consistent with the size distribution measured by the SEM.