You seem to be assuming that the 2D polymers extend indefinitely. If instead their growth is limited such that the molecules tile, overlap, and layer, they may be more amenable to manipulation such as thermoforming, thermosetting, etc.
The paper claims that they have obtained 2D sheets of very large extent, not small flakes that can overlap.
The advantages that they claim over conventional polymers, e.g. inpermeability and high tensile strength, are conditioned by such large extents. If the 2D sheets would be small enough to slide over each other and insert between other sheet fragments, so that plastic deformation would be possible, then they would also lose any advantages over traditional polymers.
> If the 2D sheets would be small enough to slide over each other and insert between other sheet fragments, so that plastic deformation would be possible, then they would also lose any advantages over traditional polymers.
I suspect that as with many composites, these qualities fall along a spectrum, and that there are significant nonlinearities (as in "a little goes a long way") that can be usefully exploited.
