Carbon nano-onion-filled polyacrylonitrile/polyethylenimine foams: structure, characteristics, and ion detoxification studies

Abstract

This study reports on novel polyacrylonitrile/polyethylenimine (PAN/PEI) blend, polyacrylonitrile/polyethylenimine/carbon nano-onion (PAN/PEI/CNO) nanocomposite and related PAN/PEI/CNO foam materials with 0.5–5 wt.% nanofiller loading. Acid functional carbon nano-onion was used as reinforcement. Foams were produced using reflux method and 2′-azobisisobutyronitrile foaming agent. Field emission scanning electron microscopy and transmission electron microscopy revealed unique hexagonal morphology with uniformly dispersed carbon nano-onion nanoparticle. Inclusion of 5 wt.% nanofiller enhanced the compression strength, modulus and density of the foams up to 68.8 MPa, 32.1 GPa, and 1.2 mgcm⁻³, respectively. Thermal stability of the nanocomposite foams was enhanced with nanofiller loading and attained V-1 rating in UL94 test. Addition of 5 wt.% CNO in PAN/PEI/CNO 5 Foam enhanced the initial weight loss (T₀), 10% degradation temperature (T₁₀), and maximum decomposition temperature (T_max) to 510, 524 °C, 555 °C, respectively. Water absorption capacity was progressively enhanced with time and was maximum for PAN/PEI/CNO 5 Foam (29.5%) after 96 h, while neat PAN/PEI foam had 19.8% water absorption in the same time period. Novel foams have been tested for the removal of toxic Pb²⁺ ions and PAN/PEI/CNO 5 Foam with 5 wt.% carbon nano-onion showed much higher removal efficiency (97%) than that of neat foam (65%).

GRAPHICAL ABSTRACT

Keywords:

• Polyacrylonitrile/polyethylenimine
• carbon nano-onion
• foam
• V-1 rating
• Pb²⁺ ions

Disclosure statement

No potential conflict of interest was reported by the author.