Laser-induced carbon nanotube microcapsules formation through depletion enhanced deposition

We report a method to fabricate carbon nanotube (CNT) microcapsule through laser-induced bubble formation in a polyethylene glycol-modified CNT (PEG-CNT) solution in the presence of PEG. A low-power laser is focused on a heat-absorbing surface to create a bubble. While PEG-CNTs in the solution are deposited on the bubble surface to form a microcapsule. The shape stability of microcapsule during swelling process is measured in different concentrations of PEG solutions. The stable CNTs microcapsules form with uniform spherical shape within 8 seconds in a 2% PEG solution, while PEG-CNTs only randomly aggregate without the presence of PEG molecules. Thus, we propose that the deposition of PEG-CNTs is enhanced by PEG molecules due to depletion interaction. Comparing with other methods, assembling PEG-CNTs microcapsules at liquid-air interface of polymer solution by optical heating greatly reduce the time and provide good quality of CNTs microcapsules. This study may enable applications of PEG-CNTs microcapsules.