Degradable and processable polymer monoliths with open-pore porosity for selective CO2 and iodine adsorption

Stimuli-directed selective detection of Cu2+ and Cr2O72- ions using a pH-responsive chitosan-poly(aminoamide) fluorescent microgel in aqueous media

In this work, the preparation of a pH-responsive fluorescent microgel, (NANO-PAMAM-CHT), is presented for the selective detection of Cu2+ and Cr2O72- ions. The NANO-PAMAM-CHT (nanosized polyaminoamide-chitosan microgel) is synthesized via aza-Michael addition reactions in a controlled and stepwise manner in water, using easily affordable starting materials like 1,4-diaminobutane, N,N'-methylene-bis-acrylamide, NIPAM and chitosan. NANO-PAMAM-CHT shows pH-responsive fluorescent properties, whereas the fluorescence intensity shows a pH-responsive change. Due to the selective fluorescence quenching, the microgel can detect both Cu2+ ions and Cr2O72- ions selectively at ambient pH in aqueous medium. Moreover, it can selectively differentiate between Cu2+ ion and Cr2O72- ions at pH ∼3 in water. The limits of detection for Cu2+ ions and Cr2O72- ions are reported as 16.9 μM and 2.62 μM, respectively (lower than the minimum allowed level in drinking water) at pH ∼7. Mechanistic study further reveals the dynamic quenching phenomenon in the presence of Cu2+ ions and static quenching in the presence of Cr2O72- ions.

Preparation of Novel Nitrogen-Rich Fluorinated Hyperbranched Poly(amide-imide) and Evaluation of Its Electrochromic Properties and Iodine Adsorption Behavior

In this study, we successfully synthesized a novel triacid monomer by means of the thermal cyclization reaction. Subsequently, a series of nitrogen-rich (A3+B2)-type fluorinated hyperbranched poly(amide-imide)s (denoted as PAI-1 and -2, respectively) were prepared by means of a one-pot method using this triacid monomer and a diamine monomer with a triphenylamine-carbazole unit as precursors. The degree of support of the prepared hyperbranched PAIs was found to be about 60% via 1H NMR calculations. Through X-ray photoelectron spectroscopy (XPS), it was found that the binding energies of C-N (398.4 eV) and -NH (399.7 eV) became lower under a current, while the binding energy peak of N+ appeared at 402.9 eV. In addition, the PAIs have good solubility and thermal stability (Tgs: 256-261 °C, T10%: 564-608 °C). Cyclic voltammetry (CV) analysis shows that the hyperbranched PAI films have good redox properties, and a range of values for the HOMO (4.83 to 4.85 eV) versus LUMO (1.85 to 1.97 eV) energy levels are calculated. The PAI films have excellent electrochromic properties: PAI-1 on coloration efficiency (CE) and transmittance change (ΔT, 852 nm) are 257 cm2/C and 62%, respectively, and have long-lasting redox properties (100 cycles). In addition, we conduct iodine adsorption tests using the structural features of PAIs with electron-drawing units, and the results show that PAI-1 had a high adsorption capacity for iodine (633 mg/g).

Stimuli-responsive fluorescent nanogel: a nonconventional donor for ratiometric temperature and pH sensing

A reactive stimuli responsive fluorescent polyaminoamide nanogel (NANO-PAMAM) is synthesized via an aza-Michael polyaddition reaction in water and subsequently transformed to a ratiometric nanosensor via post-polymerization modification of the reactive NANO-PAMAM.

Emulsion-templated porous polymers: drying condition-dependent properties

Macroporous materials templated using high internal phase emulsions (HIPEs) are promising for various applications. To date, new strategies to create emulsion-templated porous materials and to tune their properties (especially wetting properties) are still highly required. Here, we report the fabrication of macroporous polymers from oil-in-water HIPEs, bereft of conventional monomers and crosslinking monomers, by simultaneous ring-opening polymerization and interface-catalyzed condensation, without heating or removal of oxygen. The resulting macroporous polymers showed drying condition-dependent wetting properties (e.g., hydrophilicity-oleophilicity from freezing drying, hydrophilicity-oleophobicity from vacuum drying, and amphiphobicity from heat drying), densities (from 0.019 to 0.350 g cc^-1), and compressive properties. Hydrophilic-oleophilic and amphiphobic porous polymers turned hydrophilic-oleophobic simply by heating and protonation, respectively. The hydrophilic-oleophobic porous polymers could remove a small amount of water from oil-water mixtures (including surfactant-stabilized water-in-oil emulsions) by selective absorption and could remove water-soluble dyes from oil-water mixtures. Moreover, the transition in wetting properties enabled the removal of water and dyes in a controlled manner. The feature that combines simply preparation, tunable wetting properties and densities, robust compression, high absorption capacity (rate) and controllable absorption makes the porous polymers to be excellent candidates for the removal of water and water-soluble dyes from oil-water mixtures.