Engineering the surface of hybrid organic-inorganic films with orthogonal grafting of oxide nanoparticles

Superparamagnetic iron oxide nanoparticles
of magnetite have been grafted on the surface of a
hybrid organic–inorganic film prepared using an
organically modified alkoxide, 3-glycidoxypropyltrimethoxysilane,
as precursor. A solventless synthesis
of the hybrid films at high pH has been employed and
the surface chemistry of the deposited films has been
processed by controlling the aging time of the sol. The
films have been characterized by FTIR, Raman and
UV spectroscopy and grazing incidence X-ray diffraction.
Films prepared with fresh sols have shown a
mixed presence of epoxides and hydroxyls on the
surface, which enabled the successful grafting of the
iron oxide nanoparticles. Films from aged sols, which
contain only hydroxyls, have failed to bind the iron
particles but have instead shown the capability of
grafting ceria nanoparticles. This method has,
therefore, allowed a direct grafting of nanoparticles
on the hybrid surface without any post-synthetic
functionalization step. Moreover, the phase transition
induced in iron oxide nanoparticles by means of a laser
beam has been exploited to pattern the film surface
creating different domains of magnetite and hematite.