Dicker Kevin T, Ratchford Daniel, Casalini Riccardo, Thum Matthew D, Wynne James H, Lundin Jeffrey G
Chemistry Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, D.C. 20375.
Langmuir. 2020 Jul 14;36(27):7916-7924. doi: 10.1021/acs.langmuir.0c01066. Epub 2020 Jun 28.
Confinement of liquid crystals (LCs) in polymeric fibers offers a promising strategy to control liquid crystal response to external stimuli. Here, the confinement of 4-cyano-4'-pentylbiphenyl (5CB), a nematic liquid crystal, within the core of coaxially electrospun fibers composed of poly(vinylpyrrolidone) (PVP) containing different surfactants is discussed. The effects of surfactant type, surfactant concentration, and core flow rate (confinement) on the LC behavior were demonstrated using polarized optical microscopy, scanning electron microscopy, differential scanning calorimetry, Raman, and dielectric spectroscopy. Introduction of surfactant dopants of varying hydrophilic and hydrophobic components into the sheath altered the interfacial interaction between the PVP sheath and the 5CB core of the fibers. Significant effects on the LC nematic to isotropic phase transition were attributed to changes in surface anchoring between the sheath and core. Confinement of nematic LCs in surfactant doped polymeric fibers demonstrates a facile method for tuning LC phase behavior.
将液晶（LC）限制在聚合物纤维中为控制液晶对外界刺激的响应提供了一种很有前景的策略。在此，讨论了向列型液晶4-氰基-4'-戊基联苯（5CB）在由含有不同表面活性剂的聚乙烯吡咯烷酮（PVP）组成的同轴电纺纤维芯中的限制情况。使用偏光光学显微镜、扫描电子显微镜、差示扫描量热法、拉曼光谱和介电谱证明了表面活性剂类型、表面活性剂浓度和芯流速（限制）对液晶行为的影响。将具有不同亲水和疏水成分的表面活性剂掺杂剂引入鞘层会改变PVP鞘层与纤维5CB芯之间的界面相互作用。对液晶向列相到各向同性相转变的显著影响归因于鞘层与芯之间表面锚定的变化。将向列型液晶限制在掺杂表面活性剂的聚合物纤维中展示了一种调节液晶相行为的简便方法。
