This means that the nanoparticles replace {HEAD ~ a certain percentage} of {TAIL ~ the microparticles}, which causes a reduction of the viscosity  
of
This means that the nanoparticles replace { HEAD ~ a certain percentage } of { TAIL ~ the microparticles } , which causes a reduction of the viscosity
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH