4D printing of continuous flax-fibre based shape-changing hygromorph biocomposites: Towards sustainable metamaterials

4D printing focus on the integration of a targeted morphing function by controlling properties and architecture materials. The present work evaluates potential tailoring to Hygromorph BioComposite (HBC), which paves way for construction new generation sustainable shape-changing metamaterials with sequential response. HBCs are made continuous flax fibres that have been proven be relevant actuation thus due their hygromorphism function. performance can boosted selecting an appropriate matrix. soft Poly Buthylene Succinate (PBS) matrix showed 92% increase in responsiveness 500% reactivity compared Lactic Acid (PLA)/Flax HBC. Layer Height (LH) control within layers allows complex local thickness stiffness ratio. Interfilament Distance 0° oriented passive layer (IDp) offers opportunity achieve non-uniform autonomous smart surfaces. Finally, programming spatial distribution yarn combined heterogeneities. As illustration, simple compliant mechanism via localized microstructure changes is proposed.