Polymeric microspheres with a core ? shell structur
e, in contrast to microcapsules, are by definition
small
spheres which have no distinct outer layer or membr
ane and are therefore susceptible for diffusion
phenomena
1
. This leads to a wide variety of fields of applica
tion, such as in the food industry or in the
medical field as drug delivery system
2-4
. When the core of such a sphere is a comprised of
a volatile
substance, the sphere becomes expandable upon reach
ing the shells glass transition temperature and the
core substances boiling point. This has been used i
n industry since the 1970s for different purposes s
uch as
coating agents, in adhesive applications or thermal
insulation enhancement
5
.
This work is focused on the synthesis of microspher
es with a core-shell structure, whereas the core is
an
inert carbohydrate and the shell is acrylate based.
The reactions are carried out as oil in water (OIW
)
suspensions and as free radical polymerisations. Se
veral different monomers (acrylonitrile, methyl
methacrylate, acrylic acid, dipropylene glycol diac
rylat and vinyl acetate) and initiators (AIBN and D
LPO) are
used. Through the variation of the monomer ratios,
initiator variation and the OIW ratio, different sh
ell
composition can be observed. The characterization c
onducted with differential scanning calorimeter rev
eals
as expected different glass transition temperatures
and melting points for the shell. Scanning electro
n
microscopy is used to characterize the shape and si
ze of the microspheres.
Forschungs-