Langmuir-Blodgett deposition is a popular route to produce thin films of graphene oxide for applications such as transparent conductors and biosensors. Unfortunately, film morphologies vary from sample to sample, often with un-desirable characteristics such as folded sheets and patch-wise depositions. Often, differences in film morphologies are ascribed to differences in physical and chemical properties between graphene oxide samples. Here we propose that another process fundamentally limits control in Langmuir-Blodgett deposition of graphene oxide. Methanol is usually used in conventional Langmuir-Blodgett deposition to spread graphene oxide onto an air-water interface before deposition onto substrates. Here we show that methanol gives rise to the Marangoni effect which disrupts graphene oxide films during depositions. We directly showed the presence of Marangoni flow using photography, and we evaluated depositions with atomic force microscopy. The disruptive effect of Marangoni flow was demonstrated by comparing conventional Langmuir-Blodgett depositions to depositions where Marangoni flow was suppressed by addition of surfactant. Alcohol is ubiquitous as a spreading solvent for conventional Langmuir-Blodgett deposition of graphene oxide. Thus, the Marangoni effect is a general problem, and may explain the wide variety of un-desirable deposition morphologies observed in the literature.<br/>We are currently developing alternative methods for better control over graphene oxide thin film deposition. Promising results from this ongoing work will also be presented.

Langmuir-Blodgett deposition of graphene oxide — identifying Marangoni flow as a process that fundamentally limits deposition control

256th National Meeting (2018)

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