1 research outputs found
Silica-Coated Core–Shell Structured Polystyrene Nanospheres and Their Size-Dependent Mechanical Properties
The
core–shell structured PS/SiO<sub>2</sub> composite nanospheres
were synthesized on the basis of a modified Stöber method.
The mechanical properties of monodisperse nanospheres were characterized
with nanoindentation on the basis of the atomic force microscopy (AFM).
The surface morphologies of PS/SiO<sub>2</sub> composite nanospheres
was scanned with the tapping mode of AFM, and the force–distance
curves were measured with the contact mode of AFM. Different contact
models were compared for the analyses of experimental data. The elastic
moduli of PS/SiO<sub>2</sub> composite nanosphere (4–40 GPa)
and PS nanosphere (∼3.4 GPa) were obtained with the Hertz and
Johnson–Kendall–Roberts (JKR) models, respectively,
and the JKR model was proven to be more appropriate for calculating
the elastic modulus of PS/SiO<sub>2</sub> nanospheres. The elastic
modulus of SiO<sub>2</sub> shell gradually approached a constant value
(∼46 GPa) with the increase of SiO<sub>2</sub> shell thickness.
A core–shell model was proposed for describing the relationship
between PS/SiO<sub>2</sub> composite nanosphere’s elastic modulus
and shell thickness. The mechanical properties of the composite nanospheres
were reasonably explained on the basis of the growth mechanism of
PS/SiO<sub>2</sub> composite nanospheres, in particular the SiO<sub>2</sub> shell’s formation process. Available research data
of PS/SiO<sub>2</sub> composite nanospheres in this work can provide
valuable guidance for their effective application in surface engineering,
micro/nanomanufacturing, lubrication, and so on