4D Printing of Triple-Shape Memory Cyanate Composites Based on Interpenetrating Polymer Network Structures

Abstract

The triple-shape memory polymer (TSMP) can be programmed into two temporary shapes (S 1 and S 2 ) and shows an ordinal recovery from S 2 to S 1 and eventually to the permanent shape upon heating, which realizes more complex stimulus-response motions. We introduced a novel strategy for forming triple-shape memory cyanate ester (TSMCE) resins with high strength and fracture toughness via three-step curing, including four-dimensional (4D) printing, UV post-curing, and thermal curing. The obtained TSMCE resins presented two separated glass transition temperature (T g ) regions due to the formation of an interpenetrating polymer network (IPN), which successfully endowed the polymers with the triple-shape memory effect. The two T g increased with the increasing cyanate ester (CE) prepolymer content; their ranges were 82.7−102.1 °C and 164.4−229.0 °C, respectively. The fracture strain of the IPN CE resin was up to 10.9%. Moreover, the cooperation of short carbon fibers (CFs) and glass fibers (GFs) with the polymer-accelerated phase separation resulted in two well-separated T g peaks exhibiting better excellent triple-shape memory behaviors and fracture toughness. The strategy for combining the IPN structure and 4D printing provides insight into the preparation of shape memory polymers integrating high strength and toughness, multiple-shape memory effect, and multifunctionality.

Shape Memory Polymer Composites: 4D Printing, Smart Structures, and Applications

“…Wang et al. [ 143 ] introduced a novel strategy including 4D printing, UV postcuring, and thermal curing and used it to form triple SMPs with high strength and fracture toughness. They have used this strategy to print a series of 4D-printed structures to demonstrate their good processing performance.…”

4D printing of dual‐responsive high‐performance shape memory polymer inspired by sunflowers

“…[27][28][29] SMPs act as the photopolymer resin, and their shape memory effect is triggered by an external stimulus, such as heat, light, or moisture. 30,31 The use of SMPs in 4D printing has potential applications in fields such as robotics, where the ability to create self-transforming and adaptive structures could be beneficial. [32][33][34] However, additional research is necessary to optimize the utilization of SMPs as photopolymer resins and to advance LCD 3D printing technology.…”

“…4D printing involves printing a 3D object that can transform into a different shape over time in response to an external stimulus 27–29 . SMPs act as the photopolymer resin, and their shape memory effect is triggered by an external stimulus, such as heat, light, or moisture 30,31 . The use of SMPs in 4D printing has potential applications in fields such as robotics, where the ability to create self‐transforming and adaptive structures could be beneficial 32–34 …”

Mechanical metamaterials and beyond

“…Based on the literature reviewed in this work, the studies of mechanical metamaterials during the last two decades are mainly focused on fundamentals (i.e., ~70%), with the remainder being more application-oriented (30%). Different functionalities and potential applications of mechanical metamaterials have been reported within and beyond the mechanical domain at different stages, including the architected structural materials prior to 2010 163 , 164 , the structurally functional materials in the 2010s 48 , 88 , 96 , 165 – 167 , the integrated systems with property control 168 and combination 169 , inverse design 157 , 170 and multifunctional devices 6 , 12 , 171 in the 2020 s, and the deeply integrated devices in the 2030 s and after.

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