  The intact transfer and assembly of two-dimensional (2D) materials and their
heterostructures are critical for their integration into advanced electronic
and optical devices. Herein, we report a facile technique called volatile
polymer stamping (VPS) to achieve efficient transfer of 2D materials and
assembly of large-scale heterojunctions with clean interfaces. The central
feature of the VPS technique is the use of volatile polyphthalaldehyde (PPA)
together with hydrophobic polystyrene (PS). While PS enables the direct
delamination of 2D materials from hydrophilic substrates owing to water
intercalation, PPA can protect 2D materials from solution attack and maintain
their integrity during PS removal. Thereafter, PPA can be completely removed by
thermal annealing at 180 {\deg}C. The proposed VPS technique overcomes the
limitations of currently used transfer techniques, such as chemical etching
during the delamination stage, solution tearing during cleaning, and
contamination from polymer residues.
