Hot embossing and thermoforming of biodegradable three-dimensional wood structures

Hot embossing allows for low cost fabrication of nanostructures with highest aspect ratios on large surfaces and is commonly based on a large variety of polymers. The widespread use of nanostructured materials, however, poses environmental challenges. Here, we show that biodegradable wood from renewable resources can be structured on the nano-scale and that surface characteristics can be imprinted and three-dimensionally formed. In particular, we show that so-called liquid wood made out of lignin can be structured with feature sizes down to 100-200 nm and three dimensionally shaped by microthermoforming. We demonstrate optical active surfaces by diffractive elements, the change of hydrophobic to super-hydrophobic behavior and the fabrication of super-hydrophobic microfluidic channels. Based on these results we anticipate new applications in the nano- and micro-range, particularly for use in sensitive environments without posing a risk to nature. The new compound material will allow for a substitution of conventional polymers used as material in one way applications of e.g. the consumer, the food or the disposable medical industry.