Preparation And Application Of CNF/Polymer Composite Aerogel Based On Pickering Emulsion Technology

In this work,cellulose nanofibers（CNF）with high aspect ratio were extracted from sisal fiber,a kind of advantage resource of Guangxi province.The CNF aqueous dispersion as water phase and 1,2-dichloroethane（DCE）solution of water-insoluble polymer as oil phase,CNF stabilized Pickering emulsions were fabricated under a certain volume ratio of water to oil phase by ultrasonic emulsification.After a period of standing,the Pickering emulsions gels were formed.The CNF/Polymer composite aerogels with excellent mechanical property were finally obtained by freeze drying for the Pickering emulsion gels.The obtained CNF/polylactic acid（PLA）composite aerogels were modified by polymethyl hydrosiloxane（PMHS）,then the PMHS modified CNF/PLA composite aerogels with excellent hydrophobility were obtained.Their application for oil water separation and oil absorption was explored.At last,small functional molecule 1,4-dihydroxy anthraquinone（1,4-DHAQ）and PLA were together resolved into oil phase,and 1,4-DHAQ loaded CNF/PLA composite aerogel with functionality were fabricated.It can be used as fluorescence probe material for quick and sensitive detection of Cu²⁺.The detail contents were as followed.（1）Based on CNF stabilized Pickering emulsion technique,CNF/polymer composite aerogels were facilely prepared by controlling the concentration and types of polymer in the oil phase.The effect on the formation of CNF stabilized Pickering emulsion gel of concentration of CNF aqueous dispersion,concentration of polymer in the oil,volume ratio of water to oil phase and types of polymer was researched.The effect on the structure and morphology of the obtained CNF/polymer composite aerogel of concentration of polymer and types of polymer in the oil was also researched.The results showed that the obtained CNF/polymer composite aerogel had low density and porous structure,and the addition of polymer can improve the mechanical property of CNF aerogel.（2）The hydrophobic modification of the CNF/PLA composite aerogels was realized by simple chemical graft of PMHS onto the structure of CNF/PLA composite aerogels.The hydrophobic mechanism of the PMHS modification was discussed.The PMHS modified CNF/PLA composite aerogels still kept their original porous structure and had excellent hydrophobicity.Their water contact angle was increased with the dosage of PMHS increased,and the water contact angle of the CNF/PLA-3 reached up to 141.0^o,and the composite aerogel can absorb oil from water and separate oil/water maxture.（3）When the small functional molecule 1,4-dihydroxy anthraquinone（1,4-DHAQ）and PLA were together resolved into oil phase,the 1,4-DHAQ loaded CNF/PLA composite aerogels were fabricated by CNF stabilized Pickering emulsion technique.Its structure and formation mechanism were studied.As fluorescence probe material for the detection of Cu²⁺,the 1,4-DHAQ loaded CNF/PLA composite aerogels were invested by fluorescence spectrophotometer.The results showed that 1,4-DHAQ was uniformly dispersed onto the wall of pores of the 1,4-DHAQ@CNF/PLA composite aerogels.Compared with the pure 1,4-DHAQ,the obtained 1,4-DHAQ@CNF/PLA composite aerogels had better sensitivity for the detection of Cu²⁺with a low lined detection concentration of 5×10^-84.5×10^-7 mol/L,and the pure 1,4-DHAQ can only detect Cu²⁺with concentration of 5×10^-75×10^-6 mol/L.