White Light-Emitting Multistimuli-Responsive Hydrogels with Lanthanides and Carbon Dots

Abstract

Polymers that confer changes in optical properties in response to chemical or mechanical cues offer diverse sensing applications, particularly if this stimuli response is accessible in humid or aqueous environments. In this study, luminescent hydrogels were fabricated using a facile aqueous process by incorporating lanthanide ions and carbon dots (CD) into a network of polyacrylamide and poly(acrylic acid). White luminescence was obtained by tuning the balance of blue-light-emitting CD to green- and red-light-emitting lanthanide ions. Exploiting the combined specific sensitivities of the different emitters, the luminescent hydrogel showed chromic responsiveness to multiple stimuli, including pH, organic vapors, transition-metal ions, and temperature. The white-light-emitting hydrogel was also stretchable with a fracture strain of 400%. We envision this photoluminescent hydrogel to be a versatile and multifunctional material for chemical and environmental sensing.

Trends in polymeric shape memory hydrogels and hydrogel actuators

“…[82][83][84] In order to explore and mimic the more complex stimulation systems from nature, more researchers have developed novel hydrogel systems in which two or more stimuli-responsive mechanisms are combined, the so-called dual-responsive and multi-responsive hydrogel systems. [85][86][87][88] 3.2.1 Physical stimuli. By far the most studied and best understood response is that to temperature, which is one of the most favorable environmental stimuli that is used to trigger hydrogel systems that undergo sol-gel phase transitions or volume change at a critical solution temperature.…”

Physically Cross-Linked Hydrogel Based on Phenyl-1,3,5-triazine: Soft Scaffold with Aggregation-Induced Emission

“…75 Obtaining soft materials able to emit white light that can be 76 easily handled in the solid form is a challenge, and there are 77 only a few examples in literature. 34,35 Consequently, obtaining 78 such materials poses a challenge for the scientific community.…”

A Double‐Layer Mechanochromic Hydrogel with Multidirectional Force Sensing and Encryption Capability

“…Thus, the aforementioned strain‐transmittance relationship (Equation ) is considered a good approximation for this material. As CD and terpyridine all have strong absorbance in the UV range (Figure c), distinct luminescence emissions from CDs and Ln ions (Figure d) were obtained with single‐wavelength UV excitation . When the UV light passed through the top‐layer, it was partially absorbed by CDs and blue fluorescence was emitted.…”

“…Nevertheless, these devices could only response to uniaxial strain (in the direction perpendicular to the microcracks), and the response range was limited to 0–40% of strain, both of which would limit their applications in strain sensing and mapping. We recently reported on how to combine lanthanide (Ln) ions and carbon nanodots (CDs) to produce hydrogels with tunable luminescent color, including white luminescence . Under UV excitation, CDs exhibit blue emission while Ln ions (Eu 3+ and Tb 3+ ) coordinated by the ligand terpyridine display red or green emission, spectrally far from the excitation wavelength due the energy transfer from the terpyridine “antenna” molecules.…”