Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

In the current study, a core-shell structured material of MCM-48-type mesoporous silica
nanoparticles (MSNs) and cross-linked poly(N-isopropylacrylamide) homopolymer and its copolymer
with methacrylic acid was synthesized. The polymer
was preferentially grafted on the outer surface of
silane linker-functionalized MSNs based on free radical polymerization. The successful chemical grafting
of the polymer on the silica surface was confrmed by
FTIR, NMR, TG, and elemental analyses. The polymer contents of the hybrid particles vary from 18 to
40 % as determined by thermogravimetric and elemental analyses. The polymer content was tailored by varying diferent reaction parameters including monomer concentration, linker content/type, and reaction time. Well-defned uniform core-shell structured
spherical particles with an average particle size of
367 ± 25 nm and shell thickness of 29 ± 8 nm were
observed in TEM analysis. According to XRD and
nitrogen physisorption studies, the ordered mesopore
structure of the core MCM-48-type MSNs was maintained after an extended polymer grafting process and
surface coverage with a high content of polymer. No
signifcant pore blockage was observed in porosimetry analysis. More than 75% of specifc surface area,
68% of total pore volume, and the mean mesopore
diameter were retained after successful grating of
polymer on the outer silica surface. The pore volume
thus can provide enough space to encapsulate high contents of cargo molecules for applications. The narrow pore width distribution of the main mesopores of
silica determined by PALS analysis corresponds to
the N2 sorption analysis and further confrms the uniformity of the mesopores.