A new type of polymeric materials called microcellular plastics was first proposed in the early l980s. The materials are characterized with very small cell sizes (generally smaller than10μm in diameter)

uniform cell size distributions and very high cell densities (more than10

9

cells/cm

3

). Now the process technologies of microcellular plastics have been successfully developed and various products have been commercialized. Microporous materials have got extensive applications for theirs interconnected porous structure. In this paper

different techniques for the preparation of porous polymer are overviewed. Necessity of applying microcellular foaming technology to form open-cell polymeric porous material is discussed. Various approaches of preparing open-cell polymeric porous material are presented such as immiscible polymer blending

bubble coalescence model

melting extrusion foam

pore opener method and gas concentration threshold. Different method adopts different forming mechanism and has different morphology of microstructure. It can be concluded that microcellular foaming technology is a very promising means to prepare open-cell polymeric porous material.