Influence of Compression Direction on the Shape-Memory Effect of Micro-Cylinder Arrays Prepared from Semi-Crystalline Polymer Networks

Abstract

Microstructured polymeric surfaces capable of a thermally-induced shape-memory effect (SME) can perform on demand changes of surface properties such as wettability or adhesion.In this study, we explored the influence of the applied compression direction during programming, i.e. vertical compression and tilted compression, on the SME of microstructured crosslinked poly[ethylene-co-(vinyl acetate)] (cPEVA) films comprising arrays of micro-cylinders with a height of 10 µm and different diameters of 10 µm, 25 µm, and 50 µm. The shape recovery of the microstructures during heating was visualized online by optical microscopy, while atomic force microscopy (AFM) was utilized to investigate the temperature-induced shape change of single micro-cylinders. Here, the changes in micro-cylinder height and the characteristic angle θ were followed and analyzed for quantification of the shape-memory performance. Both compression modes resulted in almost flat programmed surfaces as indicated by high shape fixity ratios of Rf ≥ 93±1%. A nearly complete recovery of the micro-cylinders was obtained for all investigated cPEVA samples documented by high shape recovery values of Rr ≥ 97±1%, while the obtained shape change of the micro-cylinders during recovery almost reversely recalled the applied deformation during programming. The presented capability of SMP microstructured substrates to memorize the way of deformation during programming could be a new tool for controlling particular shape changes of microstructures during recovery and in such a way the generated local recovery forces can be adjusted.

Shape memory properties and unusual optical behaviour of an interpenetrating network of poly(ethylene oxide) and poly(2‐hydroxyethyl methacrylate)

“…Shape memory polymers (SMPs) are a new class of smart materials which can be given a temporary shape and recover their permanent shape on demand using heat or any other external stimuli such as light, electric field etc . The advantage of SMPs over shape memory alloys are that SMPs offer higher recoverable strain and a wider range of mechanical properties .…”

“…Shape memory polymers (SMPs) are a new class of smart materials which can be given a temporary shape and recover their permanent shape on demand using heat or any other external stimuli such as light, electric field etc . The advantage of SMPs over shape memory alloys are that SMPs offer higher recoverable strain and a wider range of mechanical properties . For example, a shape memory alloy (Nitinol, Ni–Ti alloy) shows maximum recoverable strain up to 8%, shape memory ceramics show maximum recoverable strain less than 1%, whereas SMPs can show recoverable strain up to 100% and the same can be tailored as a function of composition .…”

“…The advantage of SMPs over shape memory alloys are that SMPs offer higher recoverable strain and a wider range of mechanical properties . For example, a shape memory alloy (Nitinol, Ni–Ti alloy) shows maximum recoverable strain up to 8%, shape memory ceramics show maximum recoverable strain less than 1%, whereas SMPs can show recoverable strain up to 100% and the same can be tailored as a function of composition . SMPs have potential applications in almost every area of daily life: from self‐repairing auto bodies to kitchen utensils, from switches to sensors, from intelligent packing to tools .…”

Thermal Sensitive Shape Memory Behavior of Epoxy Composites Reinforced with Silicon Carbide Whiskers

“…Thermally induced SMPs are the most common type of SMP. Compared to shape memory alloys and shape memory ceramics, SMPs have been widely researched due to their facile processability, low cost, appreciable shape recovery, and broad range of shape recovery temperatures [9][10][11][12]. Therefore, they are ideal candidates for potential applications in intelligent biomedical materials, heat shrinkable packaging, smart textile, aeronautics, astronautics, sensors and actuators, information carriers, disassembly concepts, and supervision technologies for cooling chains [13][14][15][16][17][18][19][20][21].…”

Shape Memory Polymer Composites of Poly(styrene-b-butadiene-b-styrene) Copolymer/Liner Low Density Polyethylene/Fe3O4 Nanoparticles for Remote Activation

“…Shape memory polymers (SMPs) are a kind of material that can perceive external stimuli (heat, light, electric field, magnetic field, pH, specific ions and enzymes) and make a corresponding stimulation to the appropriate stimulus [1][2][3][4][5][6][7][8][9]. These SMPs have attracted more and more attention due to a wide range of applications, including smart textiles and apparel, heat shrinkable packaging, intelligent biomedical materials and self-deployable structures in spacecrafts [10][11][12][13][14].…”