Zooming in: Structural Investigations of Rheologically
Characterized Hydrogen-Bonded Low-Methoxyl Pectin Networks
- Publication date
- Publisher
Abstract
Self-assembled hydrogen-bonded networks
of the polysaccharide pectin,
a mechanically functional component of plant cell walls, have been
of recent interest as biomimetic exemplars of physical gels, and the
microrheological and strain-stiffening behaviors have been previously
investigated. Despite this detailed rheological characterization of
preformed gels, little is known about the fundamental arrangement
of the polymers into cross-linking junction zones, the size of these
bonded regions, and the resultant network architecture in these hydrogen-bonded
materials, especially in contrast to the plethora of such information
available for their well-known calcium-assembled counterparts. In
this work, in concert with pertinent rheological measurements, an
in-depth structural study of the hydrogen-bond-mediated gelation of
pectins is provided. Gels were realized by using glucona-delta-lactone
to decrease the pH of solutions of pectic polymers that had a (blockwise)
low degree of methylesterification. Small-angle X-ray scattering and
transmission electron microscopy were utilized to access structural
information on length scales on the order of nanometers to hundreds
of nanometers, while complementary mechanical properties were measured
predominantly using small amplitude oscillatory shear rheology
