Effect of thermal annealing on gas separation performance and aggregation structures of block polyimide membranes

Zhou

et al. 2022

J. Phys. Chem. Lett.

A memristor with Au/polyimide (PI)/Au structure is prepared by magnetron sputtering to investigate the multiphotoconductance resistive switching (RS) memory behavior. The PI-based memristor presents stable bipolar RS memory and is sensitive to visible light. Four discrete conductance states in both high-resistance state (HRS) and low-resistance state (LRS) are obtained when illuminating by 365, 550, 590, and 780 nm light. Electron trapping and detrapping from the defects distributed at interfaces and the PI switching layer are responsible for the observed RS memory behavior. The enhanced trapping and detrapping process by light illumination is responsible for the multiconductance states. This work provides the possibility for further development of neuromorphic vision sensors using an organic semiconductor-based memristor.

supporting

confidence: 88%

Multiphotoconductance Levels of the Organic Semiconductor of Polyimide-Based Memristor Induced by Interface Charges

Zhou

et al. 2022

J. Phys. Chem. Lett.

“…The charged resonating structure, i.e., −C(O – ) N + of NMMAPA, was substantiated from the BE at 400.8 eV (Figure S4b and Table S9). − In FCP4 , the CN functionality of imidol was previously confirmed by the FTIR peak at 2165 cm –1 (Figure S2 and Table S6). In the O1s spectrum, BEs at 531.1, 532.3, and 533.4 eV supported the coexistence of C– O of −CO O H and −CH 2 O H, C O , and −CN( O H), respectively (Figure S4c and Table S9).…”

Section: Resultsmentioning

confidence: 63%

Synthesis of Intrinsically Dual-Emissive Aliphatic Conducting Polymer and ESIPT-Associated Switching of Amide-Aggregate to Imidol-Aggregate for Sensing of Cr(III) and Fe(III)

Mitra,

Sanfui,

Roy

et al. 2023

Macromolecules

The design, synthesis, and optimization of excited-state intramolecular proton transfer (ESIPT)-associated dual-emissive aliphatic conductive polymer is one of the very challenging tasks, and has not been reported to date. Herein, aliphatic fluorescent conducting polymers (FCPs) are synthesized by polymerizing N-(monomethylol)acrylamide (MMA), acrylic acid (AA), and in situ-generated 3-N-(monomethylolacrylamido)propanoic acid (NMMAPA). Of different FCPs, the maximum population of heteroatomic nontraditional luminophores, i.e., secondary amide (−CONH), imidol (−CN(OH)), tertiary amide (−CON), and carboxylic acid (−COOH), in FCP4 is supported by the spectroscopic analyses, thermal profiles, fluorescence enhancements, and computational calculations. Thus, further investigations are made on FCP4 to explore the photophysical properties, check the suitability in dual metal ion sensing, and study the proton conductivity. The ESIPT-associated dual light emissions at 436 nm (λem1) and 573/617 nm (λem2) originate from FCP4 (amide)/FCP4 (amide)-aggregate and FCP4 (imidol)/FCP4 (imidol)-aggregate, respectively, and are supported by concentration-dependent emissions, time-correlated single photon counting studies, solvent polarity effects, and computational measurements. Regarding this, the high fluorescence quantum yields of 0.68 and 0.18 at λem1 and λem2, respectively, confirmed the ESIPT-associated strong dual emissions of FCP4. The UV spectrum within 264–300 nm, FTIR peak at 2165 cm–1, binding energies of −CN(OH)/–CN(OH) at 399.0/533.4 eV, and computational studies indicate the coexistence of FCP4 (amide)/FCP4 (amide)-aggregate and FCP4 (imidol)/FCP4 (imidol)-aggregate forms of FCP4. In FCP4, −CONH/–CN(OH)/–CON/–COOH/–CH2OH-associated dipolar and hydrogen-bonding interactions, n−π* transitions, and N-branching-associated rigidity contribute to ESIPT-associated amide–imidol phototautomerism, aggregation-enhanced emissions, dual light emissions, metal ion sensing, and conductivity. The strong coordinations of Fe(III) and Cr(III) with FCP4 (amide) and FCP4 (imidol), respectively, are supported by spectroscopic, thermal, and computational studies. The strong quenching efficiencies of Fe(III) and Cr(III) are indicated by the very low limits of detection of 0.1142 and 0.0534 ppb, respectively. The I–V and ac impedance spectroscopy data of FCP4 having 0.28 cm thickness and 1.72 cm2 area indicate high proton conductivities of 3.53 × 10–5 and 3.22 × 10–5 S cm–1 at pH = 7.0 and 8.0, respectively.

“…XRD measurements were conducted to characterize the condensed state of PEAS P1BMN3 -2 at various temperatures, 35 and the XRD curves are depicted in Figure 5c. The results showed that the diffraction peak gradually became weaker as treatment temperatures increased.…”

Section: Chemical Structurementioning

confidence: 99%

Fabrication of Rigid Polyimide Foams by Constructing Dual Crosslinking Network Structures

Luo

Shen

et al. 2023

Ind. Eng. Chem. Res.

Herein, lightweight rigid polyimide foams (PIFs) with excellent mechanical and thermal properties were fabricated by constructing dual crosslinking structures combined with the thermal foaming of polyester ammonium salt (PEAS) precursor powders. The dual crosslinking network relied on the self-crosslinking of pararosaniline base (PA) and active crosslinking derived from the breakage of CC bonds in 5-norbornene-2, 3-dicarboxylic anhydride (NA) under heating. The results showed that melt viscosity and micro-foaming behavior of PEASs and the cell morphology of PIFs could be regulated by varying the molar ratio of PA/NA and the number of repeating units amid crosslinking points. The compressive strength of PIFP1BMN3-5 (density: 165.5 kg·m–3) with dual crosslinking structures at 10% strain reached 1.36 MPa at room temperature and 0.75 MPa at 200 °C. The PIFs exhibited outstanding thermal properties with the initial thermal degradation temperature falling in a temperature range of 458.2–503.0 °C and the glass-transition temperatures exceeding 310 °C. In addition, PIFs exhibited excellent thermal insulation properties since the thermal conductivity of PIFs was between 0.048 and 0.065 W·m–1 K–1, and the temperature increase of the top surface of the cubic sample block (height: 15 mm) was approximately 20 °C when they were placed on a preheated hot stage at 200 °C for 30 min. Thus, mechanically strong rigid PIFs with dual crosslinking structures were successfully prepared, which show promising applications as lightweight, high-temperature-resistant structural materials in high-end engineering fields.