Issue 60, 2016, Issue in Progress

Design of PNIPAAM covalently grafted on halloysite nanotubes as a support for metal-based catalysts

Abstract

A thermo-responsive polymer such as poly(N-isopropylacrylamide) (PNIPAAM) was covalently grafted on the external surface of halloysite nanotubes (HNTs) by means of microwave irradiation. This nanomaterial was used as a support and stabilizer for palladium nanoparticles. The obtained HNT–PNIPAAM/PdNPs was characterized by means of TGA, SEM, EDS and TEM analyses. The palladium content of the catalyst was estimated to be 0.4 wt%. The stability of the catalytic material at different temperatures (below and above the PNIPAAM lower critical solution temperature) was tested in the Suzuki reaction under microwave irradiation. In addition, TEM analysis after five consecutive runs was performed. The catalyst showed a good catalytic activity toward the Suzuki cross-coupling reaction between phenylboronic acid and several aryl halides in aqueous media under microwave irradiation and low palladium loading (0.016 mol%, 8 μg of Pd). Turnover numbers (TONs) and frequencies (TOFs) up to 6250 and 37 500 h−1, respectively, were reached. The catalyst was easily separated from the reaction mixture by centrifugation and reused for five consecutive cycles with a small drop in its catalytic activity.

Graphical abstract: Design of PNIPAAM covalently grafted on halloysite nanotubes as a support for metal-based catalysts

Supplementary files

Article information

Article type
Paper
Submitted
09 Mar 2016
Accepted
31 May 2016
First published
02 Jun 2016

RSC Adv., 2016,6, 55312-55318

Design of PNIPAAM covalently grafted on halloysite nanotubes as a support for metal-based catalysts

M. Massaro, V. Schembri, V. Campisciano, G. Cavallaro, G. Lazzara, S. Milioto, R. Noto, F. Parisi and S. Riela, RSC Adv., 2016, 6, 55312 DOI: 10.1039/C6RA06337C

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