A review of superhydrophobic shape-memory polymers: Preparation, activation, and applications

Superhydrophobic shape-memory polymers (SMPs) have received considerable attention in the past few years. Compared with the conventional superhydrophobic and memory functional materials, superhydrophobic SMPs not only possess superhydrophobicity and memory properties but also exhibit numerous novel functionalities. Here, we systematically review the research progress on superhydrophobic SMPs, providing an overview of the synthesis technologies, activation methods, and applications of superhydrophobic SMPs. Various preparation techniques of superhydrophobic SMPs have been proposed, such as the templating technique, femtosecond lithography technique, spray method, layer-by-layer assembly method, chemical vapor deposition, and plasma etching. We provide a brief introduction of the different preparation mechanisms and discuss the respective advantages and disadvantages. Regarding the activation methods, we review the thermally driven, light-driven, magnetism-driven, electroactive, and solution-driven processes, and the corresponding activation principles are also presented. Furthermore, we summarize possible applications based on the new functionalities of superhydrophobic SMPs. Droplet manipulation can be realized by switching the hydrophobicity and adhesion of the superhydrophobic SMPs; such a manipulation scheme can be used for the nondestructive transportation of droplets, liquid manipulation platforms, droplet storage, chip information storage, microfluidic control, etc. The memory properties of superhydrophobic SMPs endow them with self-healing features, which can significantly improve their anti-corrosion performance when used as coatings. Finally, the shortcomings of superhydrophobic SMPs are discussed and propose potential directions for the future advancement of these materials are proposed.