XRD patterns of pristine SiO2, SiO2-g-POEM and
SiO2-g-PSSA nanoparticles. The pristine silica (SiO2) showed a
broad peak centered at 228, indicating its amorphous structures
[37]. Upon graft copolymerization, a general pattern was not
significantly changed but two-theta value at a peak maximum was
slightly shifted to a lower value. According to