Ionic Liquid-Based Solvents for Natural Fiber Welding: Impact of Solvent System Composition

Certain ionic liquids (ILs) are known to be efficient solvents for biopolymers, in particular for cellulosic and silk based materials¹.  The ionic liquid solvent efficiency is strongly impacted by the presence of both impurities (e.g., water, residual reagents) and intentional additives (e.g., co-solvents or diluents)^3,4.  Natural fiber welding (NFW), the process of controlled partial dissolution and regeneration of biopolymers,^5-7 is also affected by the presence of impurities and additives⁸.  

In this work we investigate the impact of impurities and additives on NFW.  The extent of NFW was characterized by x-ray diffraction, ATR-IR, SEM, and mechanical property testing.  These data are correlated with solvent physical properties, such as viscosity, density, and surface tension, as well as with solvent properties as indicated by their Kamlet-Taft parameters. 

For some of the systems investigated, there is a maximum solvent composition where polar aprotic solvents in conjunction with IL are more efficient at NFW than the IL alone.  Surprisingly, this composition occurs when the mole ratio of IL to solvent is less than one to one.  Understanding the factors that influence welding in these systems allows for greater control over the NFW process and facilitates the formation of functional biopolymer composite materials. 

 

References

 

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