Probe-Based Mechanical Data Storage on Polymers Made by Inverse Vulcanization

Fueled by big data and artificial intelligence, data-centric innovations are expected to rise exponentially in the near future. This change demands rapid advancement in alternative data storage solutions and material platforms. Probe-based data storage, such as mechanical storage using an atomic force microscope tip, offers a way forward and achieves high-density storage exceeding 4 Tb/in², surpassing hard disks. However, the storage medium must be modifiable and erasable on the nanoscale. While polymers are highly promising, they face challenges with stability, synthesis, erasing temperatures, surface roughness, and elasticity. In this study, we report a low-cost and robust polymer system that allows repeated writing, reading and erasing. The polymer was made by inverse vulcanization, a process that provides polysulfide networks with S-S bonds that can be broken and re-formed repeatedly. This property was leveraged in mechanical indentation to encode information, and thermal S-S metathesis and polymer re-flow to erase the information. Exquisite control of depth was possible for making indents over a range of 1-30 nm. This control of depth allowed encoding information using a ternary method, where the data encoded is not just a function of the presence or absence of an indent, but also the depth of the indent. This ternary coding method—the first reported for mechanical information storage on polymers—increases the data density in comparison to binary coding four-fold. Furthermore, the encoding could be done at room temperature which is rare for mechanical information storage. The polymers could also be cast as films, which facilitated rapid erasing of indents in seconds at a relatively low temperature of 140 ºC. The low cost, ease of synthesis, and dynamic S-S bonds in these polymers constitute a promising, new option for polymer storage media in probe-based data storage.