A 2D material–based transparent hydrogel with engineerable interference colours

Abstract

Transparent hydrogels are key materials for many applications, such as contact lens, imperceptible soft robotics and invisible wearable devices. Introducing large and engineerable optical anisotropy offers great prospect for endowing them with extra birefringence-based functions and exploiting their applications in see-through flexible polarization optics. However, existing transparent hydrogels suffer from limitation of low and/or non-fine engineerable birefringence. Here, we invent a transparent magneto-birefringence hydrogel with large and finely engineerable optical anisotropy. The large optical anisotropy factor of the embedded magnetic two-dimensional material gives rise to the large magneto-birefringence of the hydrogel in the transparent condition of ultra-low concentration, which is several orders of magnitude larger than usual transparent magnetic hydrogels. High transparency, large and tunable optical anisotropy cooperatively permit the magnetic patterning of interference colours in the hydrogel. The hydrogel also shows mechanochromic and thermochromic property. Our finding provides an entry point for applying hydrogel in optical anisotropy and colour centred fields, with several proof-of-concept applications been demonstrated.

An invisible hand: Hydrogen bonding guided synthesis of ultrathin two-dimensional amorphous TiO2 nanosheets

“…For the peak of Ti 2p, high content of oxygen leads to electron density shifting from the Ti atom to oxygen surface, reducing the shielding of the nuclear charge and raising the binding energy of the electrons orbiting around Ti. Compared with previous study, the so-called screening effect in Ti 2p of a-TiO 2 is weakened [53]. Therefore, the peak of Ti 2p also shifts to higher binding energy [54,55].…”

Chiral nanocrystals grown from MoS2 nanosheets enable photothermally modulated enantioselective release of antimicrobial drugs

“…Due to synergistic effects, dendritic nanoheterostructures exhibit intriguing potential for use in biological applications. Hydrogels are considered comparable carriers of nanostructures, and they can support practical applications of as-prepared dendritic nanoheterostructures 49 , 50 . DNCs were mixed in a warmed agarose aqueous solution, and the mixture was left to cool to form DNCs doped agarose hydrogels.…”

Touch-Responsive Hydrogel for Biomimetic Flytrap-Like Soft Actuator

“…Over the past decade of booming development, various kinds of smart hydrogels with stimuli responsiveness have been developed by modifying stimuli-responsive polymers [11][12][13], introducing functional additives [14][15][16] and designing ingenious structures [17][18][19]. At this stage, the stimuli-responsive smart hydrogels show multi-type changes in size, shape, optical properties, mechanical properties and electric properties adapting to various external stimuli [20][21][22][23][24][25][26][27], and they have been widely applied in soft actuators [5,[28][29][30] and other intelligence areas [31][32][33][34][35][36][37][38]. For example, Wu's group [39][40][41] reported a series of smart hydrogels with elaborately ordered structures of nano-additives, which capable of programmed deformations and actuations as soft robots under stimulation of heat, light, and electric field.…”