Ratiometric Indicator Based on Vibration-Induced Emission for in Situ and Real-Time Monitoring of Gelation Processes

Abstract

Monitoring specific processes such as gelation in a ratiometric and visual manner is of scientific value and has practical implications but remains challenging. Herein, an innovative fluorescent low-molecular-weight gelator (DPAC-CHOL) capable of revealing and self-revealing the gelation processes in situ and in real time via the ratiometric fluorescence change from orange-red to blue has been developed. By virtue of its vibration-induced emission attribute, the gelation point, critical gelation concentration, and the internal stiffness of the gel networks of DPAC-CHOL and other gelation systems could be facilely evaluated in a ratiometric and naked-eye-observable fashion. Noteworthily, the DPAC-CHOL-doped gelation system Ph-CHOL can quantitatively identify the environmental temperature in a daily-concerned range (i.e., 20-55 °C). This work not only provides a versatile advanced material but also opens up a new avenue for the investigation of gelation systems.

Fluorescent glycoconjugates and their applications

“…The fluorescence emission of these VIEgens can reversibly shift between the blue and red region when the microenvironment they exist, such as temperature, polarity and viscosity, is changed. [28][29][30][31][32][33][34][35][36][37] The present review will be divided according to the different fluorophores to which carbohydrates are conjugated, producing structurally and functionally diverse fluorescent glycoclusters. Representative examples of polymeric backbones used for building multivalent fluorescent glycoconjugates are also summarized.…”

Time–temperature–transformation (TTT) and TTT–viscosity diagrams of a typical benzoxazine resin

“…Gelation time is the time when the gelation occurs during the curing reaction, and is dependent on the reactivity of the monomers 32–34 . The gelation time can be experimentally determined using different methods such as solubility test, gel timer, dynamic thermomechanical analysis, rotational viscometer, and so forth 35–37 . In this study, parallel plate rheological test was used to determine the gelation time.…”

“…[32][33][34] The gelation time can be experimentally determined using different methods such as solubility test, gel timer, dynamic thermomechanical analysis, rotational viscometer, and so forth. [35][36][37] In this study, parallel plate rheological test was used to determine the gelation time. Constant temperature rheological testing was carried out at 160, 170, 180, 190, and 200 C. The rheological curves are shown in Figure 4.…”

Polymer-Stretching-Regulated Microscopic Photoluminescence of Vibration-Induced Emission (VIE) Molecules

“…Along with reacting to variations in the external surroundings, such as the solvent polarity, viscosity and temperature, the VIE molecules showed diverse emissions from blue to orange red through a gradual process; such emissions are inseparable from the successive changes in their conformations. The related mechanism has been fully studied in our previous reports (28)(29)(30)(31)(32)(33)(34)(35)(36). For further exploration, this research focused on microcosmic disclosure in polymer systems by photoluminescence regulation of VIE molecules (Fig.…”

“…This mechanism has been attributed to the saddle-like VIE molecules of 9,14-diphenyl-9,14-dihydrodibenzo[a,c]-phenazine and its derivatives with consecutive conformations from bent to planar (28)(29)(30)(31), resulting in appealing multicolor mission (blue and orange red) from a single molecular entity. Under different external environmental conditions, such as solvent polarity (32,33), viscosity (34,35) and temperature (36), VIE molecules display excellent photoluminescence properties with favorable reversibility and controllable regulations (37,38). Based on this phenomenon, we proposed a distinct strategy involving the exertion of an external stretching force to explore and report the very special and interesting photoluminescent characteristics of VIE molecules in poly(εcaprolactone) and ethylene vinyl acetate (EVA) polymer systems.…”