The authors have investigated the pH and ionic strength response of self-assembled layers formed by adsorption of amphiphilic weak polyelectrolytes. Using the SFA （Surface Forces Apparatus） the authors measured forc...The authors have investigated the pH and ionic strength response of self-assembled layers formed by adsorption of amphiphilic weak polyelectrolytes. Using the SFA （Surface Forces Apparatus） the authors measured force-distance profiles of poly （isoprene）-poly （acrylic acid） block copolymers adsorbed on mica. Also by Atomic Force Microscopy the authors captured single polyelectrolyte molecule adsorbed on a surface. The effect of salt concentration （Cs） and pH upon the height of the brush layers was explored mainly by measuring the forces between two adsorbed polyelectrolyte brushes. At pH = 4 our results are in good agreement with the scaling prediction L0 ∝Cs-1/3 Changing the pH from 4 to 10 causes a remarkable swelling of the polymer layer, but only a weak dependence on salt concentration was detected at the higher pH. This can be attributed to the degree of dissociation, which depends on the local pH value. At low pH the polyelectrolyte chains have a low charge density, while on increasing the pH the degree of dissociation rises, and the increased charge density is followed by swelling of the adsorbed layer. The local concentration of ions in the brush is now greater than that of pH = 4 and approximately equivalent to 0.3 M. So the swelling is only weakly dependent on salt concentration in the range 0.01-1.0 M. The results demonstrate the tunable nature of such self-assembled polyelectroiyte brushes whose height and range of interactions, can be systematically controlled by adjusting the pH and ionic strength of the medium.展开更多
Electrolyte regeneration is an important goal for environmental protection and sustainable development efforts.Herein,we report a facile strategy inspired by the transformation of edible dough from flour to regenerate...Electrolyte regeneration is an important goal for environmental protection and sustainable development efforts.Herein,we report a facile strategy inspired by the transformation of edible dough from flour to regenerate hydrogel electrolytes from their dehydrated copolymer granules(CGs)via direct addition of water or salt solution.With the aid of heating,this procedure is efficient,relatively quick,and easily implemented.The dehydrated CGs are lightweight,reusable and stable under long-term storage.Even after 5 cycles of dehydration and regeneration,the regeneration efficiency of the hydrogel electrolytes,as evaluated based on retention of mechanical strength,is over 60%.The regenerated electrolytes possess considerable ionic conductivity,reprocessability,and 3D-printability.Furthermore,an all-gel supercapacitor assembled from the regenerated hydrogel electrolyte and activated carbon electrode with CGs as binder demonstrates excellent interfacial compatibility.The assembled all-gel supercapacitor can maintain 98.7% of its original specific capacitance after 100 bending tests,and can operate in a wide temperature range spanning from-15 to 60°C.This work may provide a new access to the development of renewable materials for various applications in the fields of intelligent devices,wearable electronics and soft robotics.展开更多
文摘The authors have investigated the pH and ionic strength response of self-assembled layers formed by adsorption of amphiphilic weak polyelectrolytes. Using the SFA （Surface Forces Apparatus） the authors measured force-distance profiles of poly （isoprene）-poly （acrylic acid） block copolymers adsorbed on mica. Also by Atomic Force Microscopy the authors captured single polyelectrolyte molecule adsorbed on a surface. The effect of salt concentration （Cs） and pH upon the height of the brush layers was explored mainly by measuring the forces between two adsorbed polyelectrolyte brushes. At pH = 4 our results are in good agreement with the scaling prediction L0 ∝Cs-1/3 Changing the pH from 4 to 10 causes a remarkable swelling of the polymer layer, but only a weak dependence on salt concentration was detected at the higher pH. This can be attributed to the degree of dissociation, which depends on the local pH value. At low pH the polyelectrolyte chains have a low charge density, while on increasing the pH the degree of dissociation rises, and the increased charge density is followed by swelling of the adsorbed layer. The local concentration of ions in the brush is now greater than that of pH = 4 and approximately equivalent to 0.3 M. So the swelling is only weakly dependent on salt concentration in the range 0.01-1.0 M. The results demonstrate the tunable nature of such self-assembled polyelectroiyte brushes whose height and range of interactions, can be systematically controlled by adjusting the pH and ionic strength of the medium.
基金financially supported by the National Key R&D Program of China(2018YFC1803100 and 2016YFA0100800)the National Natural Science Foundation of China(51873156).
文摘Electrolyte regeneration is an important goal for environmental protection and sustainable development efforts.Herein,we report a facile strategy inspired by the transformation of edible dough from flour to regenerate hydrogel electrolytes from their dehydrated copolymer granules(CGs)via direct addition of water or salt solution.With the aid of heating,this procedure is efficient,relatively quick,and easily implemented.The dehydrated CGs are lightweight,reusable and stable under long-term storage.Even after 5 cycles of dehydration and regeneration,the regeneration efficiency of the hydrogel electrolytes,as evaluated based on retention of mechanical strength,is over 60%.The regenerated electrolytes possess considerable ionic conductivity,reprocessability,and 3D-printability.Furthermore,an all-gel supercapacitor assembled from the regenerated hydrogel electrolyte and activated carbon electrode with CGs as binder demonstrates excellent interfacial compatibility.The assembled all-gel supercapacitor can maintain 98.7% of its original specific capacitance after 100 bending tests,and can operate in a wide temperature range spanning from-15 to 60°C.This work may provide a new access to the development of renewable materials for various applications in the fields of intelligent devices,wearable electronics and soft robotics.
