Programmable shape-shifting 3D structures via frontal photopolymerization

• Published in: Materials & design 2021-01, Vol.198, p.109381, Article 109381
• Main Authors: Wang, Jinqiang, Dai, Ning, Jiang, Chengru, Mu, Xiaoming, Zhang, Biao, Ge, Qi, Wang, Dong
• Format: Article
• Language: English
• Subjects: Edge effect; Elastic instability; Frontal photopolymerization; Grayscale patterning; Programmable shape-shifting
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2020.109381

Shape-shifting structures have gained growing interest recently and found wide applications in areas such as soft robotics, biomedical devices and self-folding origami, attributed to their ability to construct complicated shapes directly from simple structures. However, an efficient method to design and fabricate programmable 3D shape-shifting structures from 2D polymer films still lacks. In this work, we design programmable shape-shifting 3D structures via the release of internal gradient stress using the frontal photopolymerization (FPP) method. First, the relation between the non-uniformly distributed material and loading parameters, and the geometric and fabrication parameters are established theoretically. The finite element (FE) model is then developed based on the theoretically obtained material and loading parameters. Next, the elastic instability in the shape-shifting behaviors of a cured film is captured through an elastic energy minimization. Furthermore, by using grayscale light patterns, it is shown that we can selectively manipulate the geometric and fabrication parameters to improve the design freedom of various complex 3D structures. [Display omitted] •The shape-shifting behaviors from 2D polymer films to 3D structures via FPP are studied.•A combined theoretical, experimental and numerical model is proposed to capture the shape-shifting phenomenon.•Elastic instability in the shape transition is captured using the minimization of the elastic energy.•Various 3D structures are designed by using grayscale light patterns.