A high-sensitivity long-lifetime phosphorescent RIE additive to probe free volume-related phenomena in polymers

Dini, Valentina Antonia; Gradone, Alessandro; Villa, M.; Gingras, Marc; Focarete, Maria Letizia; Ceroni, Paola; Gualandi, Chiara; Bergamini, Giacomo

doi:10.1039/d2cc05908h

Cited by 3 publications

(4 citation statements)

References 27 publications

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“…In other words, TPE is expected to be sensitive to polymer densification due to physical aging, as we previously reported for a phosphorescent AIE dye. [ 31 ]…”

Section: Resultsmentioning

confidence: 99%

“…This indicates that the observed emission variations are not the consequence of RIMs, as was instead found for another AIE dye previously investigated by some of us. [ 31 ] In the case of TPE, the source of these changes must be traced back to something else.…”

Section: Resultsmentioning

confidence: 99%

“…densification due to physical aging, as we previously reported for a phosphorescent AIE dye. [31] To verify this hypothesis, TPE-doped PLGA, which shows the clearest fluorescence variation in correspondence to its T g among the tested polymers, was selected and subjected to cycles of heating, cooling and isotherm, as described in Figure 3A, while measuring fluorescence emission by grayscale analysis. In detail, a "highly aged" sample of PLGA-TPE, obtained by storing the polymer at room temperature for several weeks, was heated above its T g (1st heating ramp, Figure 3A, green segment) and quickly cooled (fast cooling ramp, Figure 3A, blue segment) to erase its thermal history and gain an "unaged" sample.…”

Section: Investigation Of the Thermoluminochromic Responsementioning

confidence: 99%

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Emission or scattering? Discriminating the origin of responsiveness in AIEgen‐doped smart polymers using the TPE dye

et al. 2023

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Aggregation‐induced emission (AIE) luminogens are attractive dyes to probe polymer properties that depend on changes in chain mobility and free volume. When embedded in polymers the restriction of intramolecular motion (RIM) can lead to their photoluminescence quantum yield (PLQY) strong enhancement if local microviscosity increases (lowering of chain mobility and free volume). Nonetheless, measuring PLQY during stimuli, i.e. heat or mechanical stress, is technically challenging; thus, emission intensity is commonly used instead, assuming its direct correlation with the PLQY. Here, by using fluorescence lifetime as an absolute fluorescence parameter, it is demonstrated that this assumption can be invalid in many commonly encountered conditions. To this aim, different polymers are loaded with tetraphenylenethylene (TPE) and characterized during the application of thermal and mechanical stress and physical aging. Under these conditions, polymer matrix transparency variation is observed, possibly due to local changes in refractive index and to the formation of microfractures. By combining different characterization techniques, it is proved that scattering can affect the apparent emission intensity, while lifetime measurements can be used to ascertain whether the observed phenomenon is due to modifications of the photophysical properties of AIE dyes (RIM effect) or to alterations in the matrix optical properties.

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“…In other words, TPE is expected to be sensitive to polymer densification due to physical aging, as we previously reported for a phosphorescent AIE dye. [ 31 ]…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Investigation Of the Thermoluminochromic Responsementioning

confidence: 99%

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Emission or scattering? Discriminating the origin of responsiveness in AIEgen‐doped smart polymers using the TPE dye

et al. 2023

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“…An image analysis algorithm was then utilized to integrate the regions of interests Such an obvious enhancement is affected by multiple factors. First of all, mechanical deformation causes polymer chains to align more orderly along the direction of force applied, leading to the restricted intermolecular motion of the AIE molecule [69] . π-π stacking of AIE molecules might be impacted by the shrinkage of the intermolecular space, resulting in the reduced electronic coupling and enhanced emission efficiency [70] .…”

Section: Enhanced Aiegen Emission Under Mechanical Strainmentioning

confidence: 99%

Unraveling the Internal Structure of 3D Printed Stimuli-Responsive Materials Using a Molecular Probe

Kang,

Wu,

et al. 2023

Preprint

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Stimuli-responsive 3D printing, or 4D printing, offers unparalleled potential in various research fields, enabling the combination of complicated mechanical design with programmable functionalities. The switchable polymer network structures, e.g., crystalline domains, free volume, and phase separation, are the key to achieving macroscopic responsiveness. However, despite a growing repertoire of new materials, most studies rely on rudimentary imaging techniques to visualize the materials’ shape change under external stimuli. Seldomly could such macroscopic behavior be correlated with the nanoscopic structures and dynamics of polymers. Here, leveraging the AIE phenomena, we introduce a novel method that can offer direct insights into the network structures and the chain mobility of the printed polymers. We developed a new photo-polymerizable polyurethane with multiple responsive characteristics, including temperature, mechanical strain, and pH, as an example of 4D printing materials. By embedding AIEgen in the polymer matrix, we demonstrated that the emission intensity and wavelength can serve as reporters and correlate the intramolecular motions of the AIEgen with the stimuli-responsive properties of the polymers. These observations were confirmed by small-angle X-ray scattering revealing the underpinning structural evolution. With potential applications for real-time structural monitoring, this study provides a new tool for the characterization of 4D printed materials.

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Fluorescence methods to probe mass transport and sensing in solid-state nanoporous membranes

Varol,

Kaya,

Contini

et al. 2024

Mater. Adv.

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A high-sensitivity long-lifetime phosphorescent RIE additive to probe free volume-related phenomena in polymers

Abstract: The photophysical behaviour of phosphorescent rigidification-induced emission (RIE) dyes is highly affected by their micro- and nanoenvironment. The lifetime measure of RIE dyes dispersed in polymers represents an effective approach...

Cited by 3 publications

References 27 publications

Emission or scattering? Discriminating the origin of responsiveness in AIEgen‐doped smart polymers using the TPE dye

Emission or scattering? Discriminating the origin of responsiveness in AIEgen‐doped smart polymers using the TPE dye

Unraveling the Internal Structure of 3D Printed Stimuli-Responsive Materials Using a Molecular Probe

Fluorescence methods to probe mass transport and sensing in solid-state nanoporous membranes

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