Direct fabrication of porous isotactic poly-1-butene with form I from the melt using CO2.

The deformation of isotactic poly-1-butene (iPB-1) matrix, during the CO(2) -assisted foaming process, makes the iPB-1 melt crystallize into form I rather than form I', which crystallizes after annealing under high-pressure CO(2) without foaming. The result provides a new strategy to directly obtain porous iPB-1 with stable form I from iPB-1 melt.