Continuous natural fiber-reinforced shape memory polymer biocomposites: design and fabrication for sustainable self-folding architectural applications

The growing demand for sustainable building materials has driven the search for innovative solutions that minimize environmental impact while enhancing architectural functionality. Nature’s adaptability to environmental changes, such as the mimosa plant’s sensitivity to temperature and touch, has inspired the development of shape memory materials like shape memory polymers (SMPs). These materials change shape in response to external stimuli, offering promising solutions for responsive and eco-friendly applications. This study investigates the use of SMP biocomposites (SMPBCs) reinforced with continuous flax fibers for sustainable architectural applications. The main aim is to enhance the mechanical and shape memory properties of these materials, focusing on design exploration, fabrication methods, and performance evaluation for architectural use. Combining material science with digital fabrication techniques, particularly tailored fiber placement, this research integrates flax fiber into thermo-responsive epoxy-based SMPs. Origami-inspired designs, including rigid and curved folding origami, were explored using a moldless fabrication technique to optimize the SMPBCs’ performance and facilitate the creation of complex three-dimensional structures. The study began with initial prototypes of simple origami shapes, followed by three architectural prototypes representing distinct origami types. Curved folding origami enhances shape memory performance by enabling larger deformation, which increases strain energy storage and allows more effective recovery. Further exploration of single and multi degree of freedom (SDOF and MDOF) designs for architectural applications revealed that curved SDOF prototypes achieved the highest shape recovery ratio (R_r %) of 97%, while rigid MDOF prototypes showed the lowest R_r of 60% and 70%. All prototypes provided a high shape fixity ratio of nearly 100%. Moreover, initial load tests on the permanent shapes demonstrated their ability to support over 240 times their weight. This research advances sustainable architecture by showing how SMPBCs with optimal geometric designs can enable self-shaping and multifunctional applications, paving the way for more adaptive, eco-friendly building materials.