2 research outputs found
The Effect of Water on Rheology of Native Cellulose/Ionic Liquids Solutions
Cellulose coagulates
upon adding water to its solutions in ionic
liquids. Although cellulose remains in solution with much higher water
contents, here we report the effect of 0–3 wt % water on solution
rheology of cellulose in 1-butyl-3-methylimidazolium chloride and
1-ethyl-3-methylimidazolium acetate. Fourier transform infrared spectroscopy,
thermal gravimetric analysis, and polarized light microscopy were
also used to study water absorbance to the solutions. Tiny amounts
of water (0.25 wt %) can significantly affect the rheological properties
of the solutions, imparting a yield stress, while dry solutions appear
to be ordinary viscoelastic liquids. The yield stress grows linearly
with water content and saturates at a level that increases with the
square of cellulose content. Annealing the solutions containing small
amounts of water at 80 °C for 20 min transforms the samples to
the fully dissolved “dry” state
Solvent-non-solvent rapid-injection for preparing nanostructured materials from micelles to hydrogels
Due to their distinctive molecular architecture, ABA triblock copolymers will undergo specific self-assembly processes into various nanostructures upon introduction into a B-block selective solvent. Although much of the focus in ABA triblock copolymer self-assembly has been on equilibrium nanostructures, little attention has been paid to the guiding principles of nanostructure formation during non-equilibrium processing conditions. Here we report a universal and quantitative method for fabricating and controlling ABA triblock copolymer hierarchical structures using solvent-non-solvent rapid-injection processing. Plasmonic nanocomposite hydrogels containing gold nanoparticles and hierarchically-ordered hydrogels exhibiting structural color can be assembled within one minute using this rapid-injection technique. Surprisingly, the rapid-injection hydrogels display superior mechanical properties compared with those of conventional ABA hydrogels. This work will allow for translation into technologically relevant areas such as drug delivery, tissue engineering, regenerative medicine, and soft robotics, in which structure and mechanical property precision are essential. © 2019, The Author(s).11Ysciescopu