Phys.org August 7, 2019
To obtain dual stable states, the underlying mechanism must form an energy barrier between the two, where each state rested at an energetic minimum. An international team of researchers (Canada, USA – Case Western Reserve University, Louis Stokes Cleveland DVA Medical Center, University of Pittsburgh, Carnegie Mellon University) prepared sal-gel by mixing melted sodium acetate trihydrate with polymer pre-cursors of poly(acrylic acid) and a liquid mixture of acetic acid with water. The resulting gel mixture remained transparent, suggesting the constituents to be miscible with each other. The resulting gel had two solid states; a transparent soft state and an opaque rigid state that resisted deformation. The scientists transformed the sal-gel from its soft state to the rigid state via secondary nucleation through the touch of sodium acetate trihydrate seed crystals. Upon contact with a seed crystal, nucleation occurred immediately for crystallization to proceed from the point-of-contact across the entire material…read more. TECHNICAL ARTICLE 1 , 2 , 3 ,
Material behaviors of sal-gel. Credit: Nature Materials, doi: 10.1038/s41563-019-0434-0