Liquid Crystal-Functionalized Nano- and Microfibers Produced by Electrospinning
7.1 Introduction: Why Electrospinning With Liquid Crystals?
Although electrospinning is actually a rather old invention, it is currently attracting rapidly increasing attention throughout the international research community [1–8]. Among the reasons is the potential of the technique for producing extremely thin polymer fibers, which can easily be functionalized by inorganic as well as organic non-polymeric additives. By including liquid crystals inside the fibers, or by spinning the fibers from liquid crystalline polymers, a number of interesting phenomena arise [9–15], inspiring new directions of academic research and holding potential for innovative applications. The extreme stretching during the spinning process aligns a main-chain liquid crystalline polymer very well along the fiber , and electrospinning a lyotropic cellulose-based chiral nematic phase results in helical fibers . If a low molar mass liquid crystal is enclosed inside the polymer fiber the strong encapsulation in a cylindrical space with diameter in the nano-to micrometer range can have dramatic effects, e.g., expanding the liquid crystal phase sequence , inducing unusual structures of the director field or restricting normally continuously varying parameters to quantized values . Compared ...