Ca2+ Responsive Microgel-Stabilized Pickering Emulsions

As an ionic cross-linker that can change the size of poly(N-isopropylacrylamide-co-acrylic acid) microgel, Ca2+ is applied as a trigger to demulsify microgel-stabilized oil/water Pickering emulsions. The influence of Ca2+ induced intra-particle ionic cross-linking and inter-particle aggregation on the stability of microgel-stablized “Pickering” emulsion is described. At low and mediate concentration of Ca2+, ionic cross-linking can change the internal elasticity of the microgel, and cause the coarsening of the oil droplets. At high concentration of Ca2+, microgels flocculate due to the salt out effect and the emulsion is destabilized. This work provide a facile method to control the stability of the Pickering emulsions at ambient condition. GRAPHICAL ABSTRACT

[1]  Xiaoya Liu,et al.  Pickering emulsions stabilized by self-assembled colloidal particles of amphiphilic branched random poly(styrene-co-acrylic acid) , 2015 .

[2]  H. Al‐Lohedan,et al.  Surface activity of amphiphilic cationic pH-responsive poly(4-vinylpyridine) microgel at air/water interface , 2015 .

[3]  W. Richtering.  Responsive emulsions stabilized by stimuli-sensitive microgels: emulsions with special non-Pickering properties. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[4]  W. Richtering,et al.  Unraveling the 3D localization and deformation of responsive microgels at oil/water interfaces: a step forward in understanding soft emulsion stabilizers. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[5]  V. Schmitt,et al.  Origin and control of adhesion between emulsion drops stabilized by thermally sensitive soft colloidal particles. , 2012, Langmuir : the ACS journal of surfaces and colloids.

[6]  Zifu Li,et al.  Macroporous polymer from core-shell particle-stabilized Pickering emulsions. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[7]  Jianfeng Chen,et al.  Synthesis of temperature-responsive poly(N-isopropyl acrylamide)/poly(methyl methacrylate)/silica hybrid capsules from inverse pickering emulsion polymerization and their application in controlled drug release. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[8]  B. Saunders,et al.  Study of pH-responsive microgels containing methacrylic acid: effects of particle composition and added calcium. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[9]  Yongjun Zhang,et al.  Synthesis and volume phase transitions of glucose-sensitive microgels. , 2006, Biomacromolecules.

[10]  To Ngai,et al.  Novel emulsions stabilized by pH and temperature sensitive microgels. , 2005, Chemical communications.

[11]  B. Vincent,et al.  Salt-induced homoaggregation of poly(N-isopropylacrylamide) microgels , 2002 .

[12]  D. Needham,et al.  Alkali Earth Metal Binding Properties of Ionic Microgels , 2000 .

[13]  H. Wiese,et al.  Influence of metal ions on the alkali-swelling behavior of carboxylated acrylic polymer latexes , 1999 .

[14]  Morris,et al.  Adsorption of Lead Ions onto N -Isopropylacrylamide and Acrylic Acid Copolymer Microgels , 1997, Journal of colloid and interface science.

[15]  Teruo Okano,et al.  Temperature dependence of swelling of crosslinked poly(N,N′-alkyl substituted acrylamides) in water , 1990 .

[16]  W. Ramsden,et al.  Separation of solids in the surface-layers of solutions and ‘suspensions’ (observations on surface-membranes, bubbles, emulsions, and mechanical coagulation).—Preliminary account , 1904, Proceedings of the Royal Society of London.