Structure, Unique Rheologic And Assembly Properties Of Multi-walled Carbon Nanotube Fluids

In this work,novel multi-walled carbon nanotube fuids(MCNTFs)with unique rheologic behavior and assembley structures were preparaed through acids oxidation and chemical grafting.Uniform design was found to be very helpful in the production of oxidized carbon nanotubes(o-CNTs)and CNTFs.In other words,our method can produced o-CNTs with specific lengthes and functionalizations,which can pave the way for CNTFs with unique rheological responses.The optimized reaction condition for chemical grafting of DC5700 onto o-MCNTs to give DC5700-g-MCNTs are:V (MCNTs/acids):V(methol):V(40wt%DC5700/methol)=1:1:0.2,60℃/2h。Outstandingly,flocculational DC5700-g-MCNTs can be readily observed,which can be exploited for a practical protocol to protect us through rapid clearing versatile nanoparticles,including carbon nanotubes,SiO₂,TiO₂ and Fe₂O₃ etc.,from nanoparticle-polluted water system in large scale.The laboratorial and industrially viable technique can produce green nanoseparation from corrosive acid mixtures composed of carbon nanotubes.We demonstrated that the separation method is based on flocculation of arrayed nanotubes triggered by both chemical bonding and physical absorption(i.e.,Van der Waals and statistic interaction).Interestingly,well-patterned 'carbon nanotube islands' with a diameter of 1～5 microns and 'carbon nanotube rods' with～1μm diameter,5～15-μm length were found on a modified glass surface,which may pave a new assembly way for nanoparticles.100nm～500nm length MCNTs-IL with a liquid-like behavior and an excellent thermally stability was obtained.It is noticeable that ca.6.5nm thickness shell model with an ionic,perpendicular bilayer structure on the CNTs surface were verified.This finding will offer a new practical method to process "solid CNTs" or polymer/CNTs composites like macromolecules,colloids or even solutions.Our quasi 1D PEG-MCNTs nanofluids behaved an unpredicted rheology behavior greatly different from the reported 0D nanostructures.Namely,highly viscous longer PEG-MCNTs system exhibits a liquid-like behavior throughout all the temperature range of 20-80℃,but low-viscous shorter PEG-MCNTs fluids behave as an unexpected elastic solid and even can give a solid-liquid transition at 56.7℃.Our model gives the quantitative relation(1/J·x = K·exp(-Ea/RT)or a/x= K'·exp(-Ea/RT))) between functionality density,aspect ratio and volume fraction and bulk rheological response.Our finding will be very attractive,according to the above quantitative relation,because the novel controlled rheological nanofluids can be achieved via a very simple oxidation technique.And these viscoelasticity controllable nanofluids will find important applications in sensors,nanodevices,and nanocomposites and so on.