Triple Stimuli‐Responsive Flexible Shape Memory Foams with Super‐Amphiphilicity

Abstract

source. Ko et al. construct a temperature-responsive SMP film by integrating polylactic acid (PLA) and thermoplastic polyurethane (TPU). [15] Ni et al. simply adjust the layers of graphene oxide coating on SMP to design thermal-responsive devices. [16] However, the single responsive ability cannot meet the requirement of increasingly complex and changeable application environment. [17][18][19] On the other hand, the solid planar or strip geometries of traditional SMPs limit the expansion of new horizons. [20][21][22][23] Thus, it is urgent and important to fabricate 3D porous and flexible SMPs with multiresponsive function.Recent advances have progressed to use a 3D porous material as the framework added with functional fillers to construct electrical/thermal conductive networks for achieving multi-responsive SME. [24,25] MS has aroused great interest as the 3D framework for its low cost, low density, high porosity, and great elasticity. [26] Carbonbased fillers including MXene, [27][28][29] carbon nanotubes (CNT), [30][31][32] graphene, [24,[33][34][35] and carbon black (CB) are preferred candidates for their excellent photothermal and electrothermal performance. [32,36] He et al. combine the MS framework with MXene/silver nanowires (AgNWs) to design a thermal/electrical transmissive 3D network. [37] Triple-stimuli responsive shape memory composites are obtained by injecting an SMP into the hybrid framework by vacuum impregnation. Wu et al. prepare graphene nanoplatelet (GNP) hybrid-coated MS (CG@MS) incorporated with polyethylene glycol (PEG) to realize a notable photo/electrostimuli SME. [38] However, complicated and costly methods are challenging for large-scale production. [39][40][41][42][43] Meanwhile, the poor compatibility between the 3D porous framework and the functional fillers, as well as the inhomogeneous dispersion, also pose problems.An alternative method for constructing the 3D electrical/ thermal conductive network is to carbonize the MS. [44] The obtained carbon foams (CFs) actually become brittle or fragile after high-temperature carbonization. The conductivity and photothermal activity of the CFs are also not satisfactory for initiating SME at a safe voltage or realizing photothermal conversion efficiently. [45] Herein, we propose a specific multi-step carbonization protocol for transforming commercial MS to highly porous CF with robust resilience, excellent photothermal and electrothermal properties. Owing to the super-amphiphilicity of Highly porous multi-responsive shape memory foams have unique advantages in designing 3D materials with lightweight for varied applications. Herein, a facile and efficient approach to fabricating a thermo-, electro-, and photo-responsive shape memory composite foam is demonstrated. A specific multi-step carbonization protocol is adopted for transforming commercial melamine sponge (MS) to highly porous carbon foam (CF) with robust elastic resilience, efficient electrothermal/photothermal conversions, and superamphiphilicity. It is a novel proposal for CF to ta...

Fully Biobased Degradable Vitrimer Foams: Mechanical Robust, Catalyst-Free Self-Healing, and Shape Memory Properties

“…Once a cross-linked network is formed, its permanent shape cannot be changed. However, for vitrimer containing dynamic ester bonds, thermally induced dynamic transesterification imparts configurable memory properties to the material, offering possibilities for reshaping the curing material. , As shown in Figure c, when compressed from its original diameter of 34 to 15 mm, it was observed that the EPC foam could be perfectly restored to its initial state of 34 mm after heating at 120 °C and removal of external force, indicating its exceptional shape memory properties. , Additionally, in Figure d, a rectangular-shaped foam could be temporarily reshaped into an “n” shape by heating it to 120 °C (above T g ). After cooling to room temperature, the foam maintained its temporary “n” shape.…”

“…53,54 As shown in Figure 5c, when compressed from its original diameter of 34 to 15 mm, it was observed that the EPC foam could be perfectly restored to its initial state of 34 mm after heating at 120 °C and removal of external force, indicating its exceptional shape memory properties. 55,56 Additionally, in Figure 5d, a rectangular-shaped foam could be temporarily reshaped into an "n" shape by heating it to 120 °C (above T g ). After cooling to room temperature, the foam maintained its temporary "n" shape.…”

4D Printing for Biomedical Applications

“…Specific 4D printed structures can respond to multiple stimuli based on the composition of the smart structure, which can be a smart composite or a smart material with different fillers. [ 171 ] We will only focus on physical and chemical stimulation, as little information is available regarding the 4D printing of biologically responsive materials.…”

Fabrication and characterization of Trans‐1,4‐polyisoprene/carbon nanotubes nanocomposites with thermo‐ and electro‐active shape memory effects

“…Compared with thermo‐active SMPs, electro‐active shape memory polymer composites (SMPCs) have the characteristics of easy control, remote drive and fast response, which made them more suitable for biomedical and micro‐level applications 15–17 . The electro‐active SMPCs is a composite material containing with conductive fillers such as graphene oxide, 18 carbon nanotubes (CNT), 19,20 carbon black, 21,22 carbon fiber, 23,24 and silver nanowires 25,26 . Among them, CNT have excellent thermal and electrical conductivity.…”

“…[15][16][17] The electro-active SMPCs is a composite material containing with conductive fillers such as graphene oxide, 18 carbon nanotubes (CNT), 19,20 carbon black, 21,22 carbon fiber, 23,24 and silver nanowires. 25,26 Among them, CNT have excellent thermal and electrical conductivity. Particularly, singlewalled carbon nanotubes (SWCNT) have the advantages of small diameter distribution range, few defects and high uniformity, which contribute to the excellent physical properties and chemical versatility of the materials.…”