Poly(N-isopropylacrylamide-co-methacrylic acid) microgel stabilized copper nanoparticles for catalytic reduction of nitrobenzene

Abstract

Poly(N-isopropylacrylamide-co-methacrylic acid) microgels [p(NIPAM-co-MAAc)] were synthesized by precipitation polymerization of N-isopropylacrylamide and methacrylic acid in aqueous medium. These microgels were characterized by dynamic light scattering and Fourier transform infrared spectroscopy. These microgels were used as micro-reactors for in situ synthesis of copper nanoparticles using sodium borohydride (NaBH 4 ) as reducing agent. The hybrid microgels were used as catalysts for the reduction of nitrobenzene in aqueous media. The reaction was performed with different concentrations of catalyst and reducing agent. A linear relationship was found between apparent rate constant (k app ) and amount of catalyst. When the amount of catalyst was increased from 0.13 to 0.76 mg/mL then k app was increased from 0.03 to 0.14 min −1 . Activation parameters were also determined by performing reaction at two different temperatures. The catalytic process has been discussed in terms of energy of activation, enthalpy of activation and entropy of activation. The synthesized particles were found to be stable even after 14 weeks and showed catalytic activity for the reduction of nitrobenzene.

Acid hydrogel matrixes as reducing/stabilizing agent for the in-situ synthesis of Ag-nanocomposites by UV irradiation: pH effect

“…The bands at 2924 cm −1 and 2849 cm −1 were related to the stretching of -CH 3 and -CH 2groups in the polymeric chain. A broad peak from 3100 to 3600 cm −1 was due to the presence of both N-H and O-H groups [29,30], where one of them corresponds to N-H stretching (3440 cm −1 ) of NIPAM monomers and the other to O-H stretching (3300 cm −1 ) due to co-monomers. In addition, the MAA and AMPS monomers have different functional groups (carboxylic and sulfonic), which can also be identified by FTIR spectroscopy [31].…”

Viscous, Hofmeister Effect‐Enhanced Macromolecular Adhesives for Effective Bonding in Seawater

“…In addition, the absorption bands of methylene (−CH 2 ) [1550 (m) cm −1 ], carbonyl (C=O) [1735 (s) cm −1 , 1161 (w) cm −1 ] and secondary amine [−NH (stretching)] [3440 (vs) cm −1 ] were also clearly showed in FTIR spectrum (Figure 1B). [27] Then we investigated the curing ability of EHUA. As shown in Figure 1A c) and d), when EHUA was mixed with stirred seawater, it gradually condensed and solidified [28] .…”

Thermo- and pH-Responsive Behavior of Poly(<i>N</i>-isopropylacrylamide)-Block-Poly[(2-dimethylamino)ethyl Methacrylate]

“…By comparing each of the spectra, some differences can be noticed, which indicate that a new compound has been formed. FTIR spectra of PNIPAM macro-CTA and PNIPAM-b-PDMAEMA showed no C=C peak at 1600-1650 cm −1 [19], suggesting that polymerization has occurred [20]. Meanwhile, in the FTIR spectra of PNIPAM macro-CTA and PNIPAM-b-PDMAEMA, there were peaks at 3076 and 3075 cm −1 , respectively, which could be attributed to the stretching vibration of C(sp 2 )-H group but the intensity of the peak was lower in Characteristic peaks of PNIPAM in FTIR spectra of PNIPAM-b-PDMAEMA can be observed, as evidenced by the presence of the peak at 3288 cm −1 that was ascribed to N-H stretching vibration, while the peak at 1647 cm −1 was ascribed to C=O amide I and the peak at 1544 cm −1 was assigned to C=O amide II.…”