Tunable radical scavenging activity of carbon nanotubes through sonication

Abstract

Carbon nanotubes (CNTs) having controlled radical scavenging activity have been achieved tuning the content of their lattice defects induced by an ultra-sound (us) treatment. The reactivity of CNTs, subjected to ultra-sonication for different time intervals, toward 1,1-diphenyl-2-pycryl (DPPH) and hydroxyl (•OH) radicals has been estimated and related to defect concentration, evaluated through Raman spectrometry. The radical scavenging efficiency of ultra-sound treated CNTs (us-CNTs) increases with increasing the content of the structural defects, suggesting that the defect resulting from us treatment can be capitalized to obtain an amplified and controlled radical scavenging activity. The us-CNTs have been incorporated in ultra high molecular weight polyethylene (UHMWPE) matrix by hot compaction with the aim to exploit their anti-oxidant activity against photo- and thermo-oxidative degradation. The us-CNTs containing nanocomposites show progressively improved photo- and thermo-oxidative resistance with increasing the us time, highlighting that the stability of the nanocomposites can be profitably modulated by controlling the amount of CNT structural defects.