Self-assembly Behavior Of Cellulose Nanocrystals At The Water-water Interface And Application Of 3D Printing In All Aqueous Phase

Nowadays the research on all-aqueous 3D printing of structured droplets based on self-assembly of nanoparticles at the liquid-liquid interface mainly focuses on water oil two-phase system,which has poor biocompatibility.In this paper,the environmentally friendly and biocompatible aqueous two-phase system(ATPSs)was combined with the self-assembly technology of nanoparticles at the liquid-liquid interface to achieve all-aqueous 3D printing of biological systems.In the study,polyethylene glycol(PEG)and dextran aqueous solution in classical ATPSs system were selected as immiscible liquid-liquid two-phase.Cellulose nanocrystals(CNCs)were dispersed in PEG aqueous solution and chitosan was dissolved in dextran aqueous solution.CNCs and chitosan were self-assembled at the water-water interface and jamming was formed,so as to construct structured droplets.The main research results are as follows:(1)The concentration of PEG,dextran,CNCs,chitosan,pH of solution and printing speed were the decisive factors to determine the diameter,length and structural stability of 3D printing microtubules.The printed assembly film had selective permeability,and small molecules can be diffused inside the water-based thread.When the concentration of CNCs was low,the interface jamming was formed by dispersed CNCs assemblies;when the concentration of CNCs was high,the interface jamming was formed by agglomerated CNCs assemblies.With the increase of the concentration of CNCs and chitosan,the membrane thickness and the adsorption capacity of heavy metal ions were also increased,and the membrane thickness was greatly affected by the viscosity of the system.(2)Study results of Pickering emulsion and foam materials showed that:when the volume ratio of chitosan/dextran aqueous solution to CNCs/PEG aqueous solution was 1:1,the pH value of dextran phase was 3.5,and the concentration of CNCs was 1 wt.%,the emulsion droplets were irregular shape;the emulsion was more stable;the mechanical strength of foam material was higher,in other conditions,spherical droplets were formed in different degrees.