Synthesis And Applications Of Imidazolium-based Polyurethane

Polyurethanes(PUs)are a type of thermoprocessable polymer with linear block copolymer structure.They have been widely used in applications ranging from furniture and floor protective coatings and foams to biomaterials and energy storage devices.Since the structure of PUs are easy to adjust,more and more researches tend to design multifunctional PUs,such as biodegradability,antibacterial,biocompatibility,high mechanical properties,and self-healing.Ionic liquids(ILs)are defined as a type of salt composed of cation and anion pairs with melting temperature below 100℃.Due to their easily adjustable properties of cations and anions,a large number of stimuli responsive materials(including light,pH,thermal,magnetic responsive,etc.)and biomimetic materials have been designed and developed.In this work,ionic liquids are grafted or added to polyurethanes to obtain multifunctional materials.The main research work is summarized as following:(1)Synthesis of high toughness and self-healing ionic PUs were developed for antibacterial orthopedic immobilization.The self-healing PUs consist of stable soft segments and active hard segments featuring imidazolium-based ionic clusters and strong intermolecular hydrogen bonding.Interactions among the imidazolium-based ionic groups may lead to physical cross-linking of the polymer.The influence of chain mobility on the nature of self-healing by ionically modified PU containing varying substituted alkyl chain lengths(methyl,butyl or octyl groups)of imidazolium cations is investigated.As a consequence,ionic PU samples with relatively long substituted alkyl chain lengths of imidazolium cations exhibit enhanced self-healing behavior.Moreover,the presented PUs showed good antibacterial features and were easily reshaped;therefore,they are promising for applications as orthopedic immobilization devices to wrap around and support fracture sites.(2)Synthesis of thermochromic actuator based on TEAPU/[Bmim]2[NiCl4]by solvent evaporation.[Bmim]2[NiCl4]is reversibly thermochromic by interaction with water molecules to change configuration between octahedral and tetrahedral.Besides,[Bmim]2[NiCl4]could change color quickly in the temperature range(30～50℃).What’s more.the composite could change color and shape simultaneously by simulating natural flowers.It is believed that the material have potential application in artificial muscleand smart windows.