Detecting topology freezing transition temperature of vitrimers by AIE luminogens

Abstract

Vitrimers are one kind of covalently crosslinked polymers that can be reprocessed. Topology freezing transition temperature (T v ) is vitrimer’s upper limit temperature for service and lower temperature for recycle. However, there has been no proper method to detect the intrinsic T v till now. Even worse, current testing methods may lead to a misunderstanding of vitrimers. Here we provide a sensitive and universal method by doping or swelling aggregation-induced-emission (AIE) luminogens into vitrimers. The fluorescence of AIE-luminogens changes dramatically below and over T v , providing an accurate method to measure T v without the interference of external force. Moreover, according to this method, T v is independent of catalyst loading. The opposite idea has been kept for a long time. This method not only is helpful for the practical application of vitrimers so as to reduce white wastes, but also may facilitate deep understanding of vitrimers and further development of functional polymer materials.

A self-healing supramolecular hydrogel with temperature-responsive fluorescence based on an AIE luminogen

“…S4 †) because the ionic interactions between TPPE and the PAMPS chain were relatively weak as they were largely dissociated in the solution, resulting in the increase in the motional freedom of TPPE than that in the TPPE-PAA hydrogel. In accordance with some recent studies, [27][28][29][30] this work showed that the uorescence enhancement of the AIE luminogen had a close relationship with the macromolecule motion ability and the supramolecular interaction; thus, AIE luminogens might be used as the indicator of the thermomotion of polymer chains in the solution state.…”

“…[23][24][25][26][27][28] Besides, some groups reported the monitoring of the transition temperature by introducing AIE units into polymer chains, which illustrated the potential application of the AIE units as uorescent probes. For example, Bao et al developed a sensitive and reliable approach for the detection of the glass transition temperature (T g ) of polymers using tetraphenylethene derivatives as uorescent sensors; 29 Yang and coworkers proposed an efficient method to measure the topology freezing transition temperature (T v ) of a vitrimer by the uorescence change in the AIE molecules; 30 Wang et al reported enhanced uorescence emission around the lower critical solution temperature (LCST) by importing the AIE property into the thermo-responsive polymer. 31 These studies employed the characteristics of AIE for the indication of the polymer phase transition; however, there are few examples where AIE luminogens are utilized as uorescent indicators to characterize supramolecular interactions and macromolecular motions without aggregation.…”

Toward Stimuli‐Responsive Dynamic Thermosets through Continuous Development and Improvements in Covalent Adaptable Networks (CANs)

“…In a recent paper, Yang et al65 were able to employ a fluorescent probe to monitor network relaxation in vitrimers. Aggregation‐induced‐emission (AIR) luminogens are fluorescent organic compounds that are highly emissive when restriction of intramolecular motion (e.g., in an aggregated state) causes the dissipation of absorbed energy via radiation.…”

Reprocessable Thermoset Soft Actuators

“…Our strategy for reprocessing traditional LCETs originated from our serendipitous finding . Recently we measured T v by an aggregation‐induced emission (AIE) probe technique.…”

“…We found that, as for vitrimers that contain a certain amount of transesterification catalyst, the traditional epoxy thermoset without any catalysts possesses the same topology freezing transition temperature (ca. 102 °C), which indicates a dramatic change of reaction rate . The existence of this transition, with or without the catalyst, indicates that the traditional epoxy thermosets should share a similar topology rearrangement potential and consequent reprocessability as typical vitrimers.…”