Mechanochemically conjugated PMHSano-SiO_2 hybrid and subsequent optimum grafting density study

摘要

In this paper, we reported the preparation of poly(methylhydrosiloxane) (PMHS)/SiO_2 hybrid particles by mechanochemical method based on high energy ball milling (HEBM). The obtained hybrid particles were characterized by Fourier transform infrared (FT-IR) spectroscopy, ~(29)Si CP (cross-polarization) MAS NMR, viscosity measurement, particle size distribution, thermal analysis (TGA, DSC and DTG), static contact angle (CA), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). FT-IR and ~(29)Si CP MAS NMR spectra indicate that PMHS is chemically anchored onto the surface of nano-SiO_2. Viscosity measurement, particle size distribution, FE-SEM and TEM demonstrate that an appropriate grafting density optimizes the dispersion of nanoparticles in poly(dimethylsiloxane) (PDMS) matrix, so lower viscosity can be achieved. Too high or too low grafting density may only achieve sub-optimal and poor dispersions. The optimum grafting density of PMHS on nano-SiO_2 was determined by thermal analysis, with approximately 0.0531 PMHSm~2. Static contact angle measurement indicates that the water contact angle of hybrid particles is modulated by changing the grafting density of PMHS on nano-SiO_2. The CA value of PMHS/SiO_2 hybrid with optimum grafting density is 139.4°, and the highest CA value of PMHS/SiO_2 hybrid is approximately 158.2°.