Palladium nanoparticles capped by thermoresponsive N‐heterocyclic carbene: Two different approaches for a comparative study

Abstract

In this article, we reported the synthesis of thermoresponsive palladium nanoparticles, stabilized by polymer‐tagged N‐heterocyclic carbenes (NHCs), using two different approaches. In one case, the nanoparticles were synthesized from the NHC–palladium complex, while in other cases, palladium nanoparticles and NHC were synthesized simultaneously for the in situ cappings of the nanomaterial. While the thermoresponsive nature of the nanomaterials was observed in both cases, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) analyses showed distinct characteristics in the thermal behavior of those materials. High‐resolution transmission electron microscopic (HRTEM) and scanning electron microscopic studies separately revealed temperature‐dependent aggregation in both cases although separate patterns were observed when the nanomaterials were synthesized using different approaches. Finally, both the nanomaterials were successfully used as a recyclable catalyst for Suzuki reactions in an aqueous medium, with slightly different catalytic activity, plausibly due to variations in the size of the nanoparticles.

Investigating the degradation of PET utilizing NHC‐based catalysts and effective reuse of the degradation product as an additive with polyurethane adhesive material

“…As we have reported in our previous works, in the case of the PNIPAM‐NHC‐Pd (II) complex (catalyst A), the breakage of the NHC‐Pd bond will occur at 217°C, which is higher than the experimental temperature value (170–190°C) 22 . Whereas on the other hand, in the case of PNIPAM‐NHC‐Pd (0) (catalyst B), such breaking of NHC‐Pd bond starts from a much lower temperature, around 182°C, which is close to the experimental temperature 19 . Thus, as a result, catalyst B can easily produce the effective PNIPAM‐N‐heterocyclic carbenes in situ during the experimental conditions, which will aid the glycolysis of PET.…”

“…PNIPAM tagged NHC‐Pd (II) complex and PNIPAM tagged NHC‐Pd (0) nanoparticles were synthesized using our previously reported literature 19 . In brief, the PNIPAM‐NHC precursor, was treated with palladium chloride using pyridine as a solvent to get PNIPAM‐NHC‐Pd (II) complex which is labeled as catalyst A.…”

“…Catalysts (catalyst A and B) were synthesized using our previously reported literature. 19 The percentage of degradation of PET was calculated using the following equation.…”

“…PNIPAM tagged NHC-Pd (II) complex and PNIPAM tagged NHC-Pd (0) nanoparticles were synthesized using our previously reported literature. 19 In brief, the PNIPAM-NHC precursor, was treated with palladium chloride using pyridine as a solvent to get PNIPAM-NHC-Pd (II) complex which is labeled as catalyst A. Similarly, PNIPAM-NHC precursor and palladium diacetate (Pd [OAC] 2 ) was taken in dimethylsulfoxide (DMSO) solvent and reacted at 50 C for 3 h and at 100 C for 30 mins to get the PNIPAM-NHC-Pd (0) nanoparticles (catalyst B).…”

“…22 Whereas on the other hand, in the case of PNIPAM-NHC-Pd (0) (catalyst B), such breaking of NHC-Pd bond starts from a much lower temperature, around 182 C, which is close to the experimental temperature. 19 Thus, as a result, catalyst B can easily produce the effective PNIPAM-Nheterocyclic carbenes in situ during the experimental conditions, which will aid the glycolysis of PET. Thus, owing to the in situ formation of PNIPAM-NHC, catalyst B showed a higher PET degradation percentage at 180 C than that of catalyst A.…”