The addition of particles during
the sol-to-gel conversion process
generally enhances the mechanical properties of the resulting hydrogels.
However, the impact of the addition of porous particles during such
a process remains an open question. Herein, we report hydrogel-to-elastomer
conversions by natural porous particles called diatom frustule silica,
namely, Melosira nummuloides. The surface pores provide
mechanical interlocking points for polymers that are reinforced by
gelation. The most critical aspect when choosing polymeric materials
is the presence of water-resistant adhesion moieties, such as catechol,
along a polymer chain, such as chitosan. Without catechol, no sol-to-gel
conversion is observed; thus, no elastomeric hydrogel is produced.
The resulting hybrid gel reveals reversible compressibility up to
a 60% strain and high stretchability even up to ∼400% in area.
Further, in vivo study demonstrates that the hybrid
composite gel can be used as a therapeutic for pressure-induced ulcers.
The synergy of chemical adhesion and physical chain entanglement via pores provides a way to fabricate a new class of 100%
water-based elastomeric materials.
Quantitative analysis of tension and compression imposed on surfaces of bending polymer films plays a key role in the design of flexible electronic devices. For over a decade, the analysis has relied on the classical beam theory that mainly deals with metals, glass, and cement; however, the applicable limit of the theory to largely bending polymer films has never been validated. We present that the classical beam theory accurately analyzes surface bending strains in single-layer and double-layer polymer films through measuring the strains by a surface-labeled grating method. The experimental analysis reveals that the bending strains on the outer and inner surfaces of the single-layer film are symmetrical, whereas those of the double-layer film are asymmetrical. These results are well explained by the classical beam theory considering stress–strain curves of polymer films. This approach will further advance the strain design of polymer films, which aids in the development of mechanically durable devices.
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