Automatically Programmable Shape‐Memory Polymers Based on Asymmetric Swelling of Bilayer Structures

• Published in: Macromolecular rapid communications. 2018-05, Vol.39 (9), p.e1800039-n/a
• Main Authors: Tang, Junkun, Zhou, Yan, Wan, Liqiang, Huang, Farong
• Format: Article
• Language: English
• Subjects: asymmetric swelling; automatic programming; bilayer structures; Complexity; Deformation; Drying; Polymers; Programming; Reproducibility; reversible; Shape memory; shape‐memory polymers; Swelling; Warm water
• ISSN: 1022-1336; 1521-3927
• DOI: 10.1002/marc.201800039

Shape‐memory polymers (SMPs) possess the capability to change shapes upon stimulation; however, the programming process that determines the temporary shape cannot proceed without external manipulation, which may greatly affect the shape complexity, accuracy, and reproducibility. Here, an automatically programmable SMP (AP‐SMP) based on asymmetric swelling of bilayer SMP structures is demonstrated without external manipulation. In the automatic programming process, the AP‐SMP can be deformed by the swelling of its hydrophilic hinge film in warm water to a temporary shape, which could be fixed by the glass transition of the two SMP films through cooling and drying in air. Owing to the unique ability, many complex shapes can be easily customized through diverse design strategies. Moreover, the AP‐SMPs can reversibly transform between the permanent and temporary shapes, and both shapes are free‐standing in normal conditions. The automatic programming of AP‐SMPs may greatly expand the potential application range of SMPs. A kind of automatically programmable shape‐memory polymer based on asymmetric swelling of bilayer structures is introduced. Many complex, 3D shapes can be facilely created through diverse design strategies during or after material preparation. The polymers exhibit a reversible shape‐memory effect, and both of their permanent and temporary shapes are free‐standing under normal conditions.