Plant tissues are constructed as composite material systems
of
stiff cellulose microfibers reinforcing a soft matrix. Thus, they
comprise smart and multifunctional structures that can change shape
in response to external stimuli due to asymmetrical fiber alignment
and possess robust mechanical properties. Herein, we demonstrate the
biomimetics of the plant material system using silk fiber-reinforced
alginate hydrogel matrix biocomposites. We fabricate single and bilamellar
biocomposites with different fiber orientations. The mechanical behavior
of the biocomposites is nonlinear, with large deformations, as in
plant tissues. In general, the bilamellar system shows increased modulus,
strain UTS, and toughness compared to the single-lamellar system for
most of the tested orientations. Overall, the biocomposites present
a wide range of elastic modulus values (3.0 ± 0.6–104.7
± 11.3 MPa) and UTS values (0.23 ± 0.04–12.5 ±
2.0 MPa). The bilamellar biocomposites demonstrated
shape-transforming abilities with diverse morphing modes, emulating
different plant tissues and creating complex shape-morphing structures.
These multifunctional biocomposites possess tunable and robust mechanical
properties, controllable shape-morphing deformations, and the ability
to self-controlled encapsulation, grip, and release objects. By harnessing
biomimetic principles, these soft, smart, and multifunctional materials
hold potential applications spanning from soft robotics, medicine,
and tissue engineering to sensing and drug delivery.