1 research outputs found
Equilibrium Swelling, Interstitial Forces, and Water Structuring in Phytoglycogen Nanoparticle Films
Phytoglycogen
is a highly branched polymer of glucose that forms
dendrimeric nanoparticles. This special structure leads to a strong
interaction with water that produces exceptional properties such as
high water retention, low viscosity, and high stability of aqueous
dispersions. We have used ellipsometry at controlled relative humidity
(RH) to measure the equilibrium swelling of ultrathin films of phytoglycogen,
which directly probes the interstitial forces acting within the films.
Comparison of the swelling behavior of films of highly branched phytoglycogen
to that of other glucose-based polysaccharides shows that the chain
architecture plays an important role in determining both the strong,
short-range repulsion of the chains at low RH and the repulsive hydration
forces at high RH. In particular, the length scale λ<sub>0</sub> that characterizes the exponentially decaying hydration forces provides
a quantitative, RH-independent measure of film swelling that differs
significantly for different glucose-based polysaccharides. By combining
ellipsometry with infrared spectroscopy, we have determined the relationship
between water structuring and inter-chain separation in the highly
branched phytoglycogen nanoparticles, with maintenance of a high degree
of water structure as the film swells significantly at high RH. These
insights into the structure–hydration relationship for phytoglycogen
are essential to the development of new products and technologies
based on this sustainable nanomaterial