Reconfigurable Anticounterfeiting Coatings Enabled by Macroporous Shape Memory Polymers

Abstract

Here, we report a new type of reconfigurable anticounterfeiting coating enabled by integrating the scientific principles of photonic crystal and shape memory polymer (SMP). The autonomous infusion of uncured oligomers in a polydimethylsiloxane (PDMS) stamp into a templated macroporous SMP photonic crystal coating, which was confirmed by quantitative X-ray photoelectron spectroscopy analysis, can program an iridescent pattern on the transparent SMP membrane with deformed macropores. By manipulation of the unconventional all-room-temperature shape memory effects exhibited by the shape memory copolymer comprising polyethylene glycol diacrylate and ethoxylated trimethylolpropane triacrylate, the iridescent pattern can be easily and instantaneously concealed and revealed by immersing in common household liquids (e.g., ethanol and water). Systematic experiments and theoretical simulations using scanning electron microscopy, atomic force microscopy, optical spectroscopy, scalar wave approximation modeling, and contact angle measurements reveal the major mechanism underlying the anticounterfeiting concealing and revealing processes: the compressive deformation of periodic macropores induced by capillary pressure created by solvent evaporation. Apparent water contact angle measurements show that the infusion of hydrophobic PDMS oligomers into hydrophilic macroporous SMP coatings leads to a large increase in water contact angle from ∼35° to ∼70°, which significantly changes the capillary pressure and the final configuration of the SMP photonic crystals. In addition to rendering a facile anticounterfeiting mechanism, the novel oligomer-infusion-induced chromogenic effects and modification of surface wettability might lead to important applications in developing new chromogenic sensors for noninvasively monitoring molecular diffusion at solid–solid interfaces and durable superhydrophobic and/or superomniphobic coatings.

Switching microobjects from low to high aspect ratios using a shape-memory effect

“…DSC data were collected from the second heating cycle (À100 to +150 1C, 10 K min À1 , nitrogen atmosphere). Laser diffraction (Mastersizer 2000, Malvern) was performed in water for MP and in DCM for pre-swollen MN, where scattering artefacts were excluded when determining the volume-weighted mean diameter D [4,3]. For solvent triggered shape switching, DCM was added to programmed MN deposited on a glass slide and later evaporated, while continuously monitoring particle shape by light microscopy (DMI 6000B, Leica).…”

“…Depending on the stress level created by this effect, a connected secondary object can be moved. In this way, SMP can be used as thermomechanical energy storage systems, which enable self-sufficient devices such as deployable antenna, 2 anti-counterfeit labels, 3 the anchoring of medical implants 4 and the driving of attached propellers. 5 The shape-memory effect (SME) works well in miniaturized objects down to the submicron level.…”

Quadruple Anti‐Counterfeiting Retroreflective Structural Color Films

“…And the heat treatment used here is more environmentally friendly than organic vapors used for shape memory polymer‐based PCs. [ 20 ]…”

Swelling and Shrinking Behavior of Modified Starch Biopolymer with Iron Oxide

“…[26,27] The modified properties of biopolymer [28][29][30][31][32] can be utilized in different applications such as polymer electrolytes for lithium batteries, [33] electronic applications, [34,35] as a membranes for separation, as a catalysis, lab-on-chip technologies, stimuli-responsive shape memory polymer, [36] biomedical application, [37,38] orthopedic surgery, [39] tissue engineering, and 3D printed scaffolds for bone tissue regeneration. [40] The biopolymer based design can be inspired from mussel-inspired crosslinking, [41] microporous shape memory polymers, [42] biomaterials science and engineering. [43,44] Here, the current study is focused on the development of a biodegradable iron oxide binder with starch-based biocomposites.…”