Microengineering of Polymers and Polymeric Surfaces

For many applications in biomedicine, not only the multifunctionality but also the macroscopic structure or architecture of polymers is relevant. For example, cells can align to patterns on polymeric surfaces and are influenced by the macroscopic surface pattern of the underlying substrate. In this chapter, a short overview is presented on selected methods to structure polymers or polymer surfaces by microengineering techniques (Table 3.5) [97]. 

The most prominent technique among these is based on soft lithography [97]. This set of methods allows the generation of micropattemed polymer surfaces or microparticles of different shapes. Each method has certain limits such as scale and aspect ratio (cf. Table 3.5) that will be discussed in detail. Initially, two methods from soft lithography micropatterning and micromolding will be described, originally developed by Whitesides and coworkers. The technique relies on an elastomeric soft material that is either used as a stamp or as a mold in order to pattern surfaces 2D with a monolayer or 3D with a microstmcture (Fig. 3.65). In the first case, one can obtain a fine monolayer pattern (-lOOnrn) but no aspect ratio can be obtained. Nevertheless, by 

TABLE 3.5 MeHiods to Structure Polymers or Pidymer Surfaces by Microengineering Techniques 

Micromolding and PRINT (particle replication in nonwetting template) lOOnm/medium [99,100] 

Droplet-based microfluidics 100pm/small (spherical) [103,104] 

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