Complete CNT disentanglement–dispersion–functionalisation in a pulsating micro-structured reactor

Disentanglement, dispersion of CNTs without attrition and efficient interfacial interaction with polymer chains are a major challenge in developing CNT/polymer composites. In the present device the mixture of highly viscous polyphosphoric acid (PPA) and entangled MWCNTs fills a hollow cylinder where a perforated piston, encasing micro-grids, is axially translating, oscillating and simultaneously rotating. This generates an extensional-shear-spiralling flow, magnified in the entrance/exit zone of the grid micro-openings, the smallest having diameter of 40μm. The reciprocating action forces the agglomerates to cross the grid many times, while the oscillation reduces effectively the clogging of the grid. Flow micro-splitting and recombination, across millions of micro-openings in a time dependent regime, facilitated erosion and collision mechanisms to prevail, leading to a gradual CNT deagglomeration–dispersion without CNT attrition. The resulting high multi-directional-rotational flow generated the conditions for efficient functionalisation.