Multifunctional responsive fibers produced by dual liquid crystal core electrospinning†
We demonstrate that coaxial electrospinning with more than one core channel, each containing a different type of liquid crystal, can be used to produce multifunctional fibers in a one-step process. They respond to more than one stimulus or with multiple threshold values, and the individual cores may feature different physical properties such as iridescent reflection in one core and birefringence in another. In order to ensure good fiber morphology and intact, unmixed and well separated cores, two important precautions must be taken. First, the fibers should not be collected on a hydrophilic substrate, as this will lead to severe fiber deformation and core mixing after collection, as a result of capillary forces from the water that condenses on the fiber during spinning. Second, the addition of surfactants to the polymer solution should be avoided, although it may appear beneficial for the spinning process as it reduces surface tension and increases conductivity. This is because the surfactant enters the liquid crystal core, possibly together with water in the form of inverse micelles, seriously degrading the performance of the liquid crystal.