Search for: All records

In this work, we present the fabrication of a two-step thermoresponsive ultrafiltration (UF) membrane through polymerization of a lyotropic liquid crystal (LLC). A mixture of commercially available Pluronic F127 block copolymer, water (containing ammonium persulfate as the initiator), and polymerizable oil (n-butyl acrylate/ethylene glycol dimethacrylate) is used to create an LLC with lamellar structure, as characterized by cross-polarized light microscopy and atomic force microscopy. Differential scanning calorimetry is employed to evaluate the thermoresponsive behavior of the polymerized LLC (polyLLC). Two-step thermoresponsiveness (~35 °C and ~50 °C) of the polyLLC is observed due to the lower critical solution temperature (LCST) of F127 and melting of the crystalline structure of the polyethylene oxide (PEO) chains of the F127 surfactant. In the next step, the obtained mesophase is cast on a nonwoven polyester support sheet followed by thermal polymerization. The hydration capacity, water flux, water flux recovery after fouling, and molecular weight cut-off (MWCO) of the obtained membrane are evaluated at different temperatures to examine its thermoresponsiveness. The experimental results reveal that the UF membrane has a reversible thermoresponsive behavior at the LCST and PEO melting of polyLLC. Additionally, cleaning efficiency of the fouled membrane can be enhanced by using its thermoresponsive behavior, resulting in an extended lifetime of the product. Furthermore, the MWCO of the membrane can be altered with temperature due to the pore size change with temperature stimulus. 

Lyotropic liquid crystals (LLCs) have drawn attention in numerous technical fields as they feature a variety of nanometer-scale structures, processability, and diverse chemical functionality. However, they suffer from poor mechanical properties and thermal stability. Polymerization in LLCs, referred to as LLC templating, is an effective approach to overcome this issue. While the templating approach results in robust mechanical, physical, and thermal properties, retention of the parent LLC structure after polymerization has been a major concern in the field. Therefore, there have been several efforts to introduce new materials and techniques to preserve the native LLC nanostructure after polymerization. In this review, we survey the efforts put in this area along with the applications of the obtained materials from LLC templating, after providing a brief introduction of LLC structures. Moreover, polymerization kinetics in different LLC structures, as a key player in the structure retention, are analyzed. Furthermore, we discuss the outlook of the field and available opportunities.