Video clip 4 - Scaffold formation (Part 2 of 2)

Following on from Video Clip 3... here we see the polymer in a fully plasticised liquid-like state foaming into a solid porous scaffold.

The pressure within the autoclave is released by venting the supercritical CO₂ through an outlet pipe. The CO₂ within the liquid-like polymer escapes and you can observe a reduction in the height of the polymer's meniscus from the bottom of the container.

Once the pressure has reached decreased to a certain point, the conditions inside the autoclave are no longer adequate in sustaining the liquid-like polymer state.

At this point the polymer reverts back to a solid and since trapped CO₂ is still trying to escape we see a sudden "explosion" or foaming of the polymer, hence forming a porous scaffold.

Video clip 5: The phase changes of SbF₆