Microgels are crosslinked polymer colloids with unique internal networks, exhibiting distinctive mechanical behaviors that are strongly governed by their nanoscale structure. However, establishing direct correlations between nanoscale organization and macroscopic mechanical properties remains challenging. This study aimed to characterise the structural and mechanical properties of pectin microgels using novel techniques to bridge the gap between their internal configuration and functional mechanics.

In the first study, a spray-gelation method was developed to efficiently fabricate pectin microgels with reproducible properties. Microgels were produced from low-methoxyl (LMP) and amidated low-methoxyl pectin (A-LMP), crosslinked with calcium ions at three concentrations (40, 80, and 200 mM) under acidic (pH 2.0) and neutral (pH 7.0) conditions. The resulting microgels were systematically characterized for yield, density, particle size, morphology, and surface features. Higher calcium concentrations and pH produced smaller, more uniform particles due to accelerated gelation. Unexpectedly, all pectin microgels were found to be non-interfacially active, in contrast to previous studies. Overall, the spray-gelation method offers a robust platform for the reproducible fabrication of pectin microgels and can be extended to other ionic polysaccharides.

In the second study, the internal structure and mechanical properties of these microgels were investigated to establish links between nanoscale configuration and functional mechanics. Transmission electron microscopy (TEM) of resin-embedded particles revealed that LMP microgels prepared at higher calcium concentrations and neutral pH exhibited more compact and uniform network structures due to enhanced junction-zone formation, whereas amidated pectin aggregated clusters that disrupted network linearity. Single-particle mechanical measurements using a cantilevered-capillary force apparatus (CCFA) further established clear correlations between network architecture, microgel elasticity, and deformability.

Together, these findings provide new insights into the interplay between microgel internal structure and mechanics, offering valuable design principles for developing next-generation biopolymeric microgels with tailored functionality for applications in food systems, drug delivery, and stimuli-responsive soft materials.