Heteroaggregation of multiwalled carbon nanotubes and zinc sulfide nanoparticles

In this work, the heteroaggregation kinetics between positively and negatively charged variants of multiwalled CNTs with positively charged zinc sulfide (ZnS) nanoparticles was studied. Through time-dependent size measurements, we observed an increasing rate of heteroaggregation between negatively charged nanotubes and positively charged ZnS nanoparticles with increasing ZnS/CNT ratios. The heteroaggregation rate increases to a maximum at a ZnS/CNT weight ratio of 4.8, then reverses in trend. Time-dependent zeta potential measurements also revealed that during heteroaggregation, the negatively charged nanotubes are continuously coated by the positively charged ZnS nanoparticles. When the surface of the CNTs is oversaturated with ZnS nanoparticles, the aggregates behave as single positively charged entities hindering further growth in size through inter-aggregate repulsion. No heteroaggregation was observed between positively charged CNTs and positively charged ZnS nanoparticles. TEM imaging supported the notion of ZnS nanoparticles attached to CNTs. Using heteroaggregation, we further successfully prepared composites from functionalized CNT and ZnS phosphors with good distribution of the nanotubes on the phosphors.

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