New stimuli-responsive polyampholyte: Effect of chemical structure and composition on solution properties and swelling mechanism

Functional macroporous amphoteric polyelectrolyte monoliths with tunable structures and properties through emulsion-templated synthesis

HYPOTHESIS

Macroporous polyampholyte hydrogels, simultaneously bearing both the anionic and cationic groups, demonstrate immense promise over the one-sign charged polyelectrolytes, owing to a unique phenomenon known as the ˝anti-polyelectrolyte˝ effect. Thus, they are extremely promising materials, since they remain solvated and functional even in harsh conditions. Furthermore, macroporous morphology significantly enhances polyampholyte response to external stimuli, since it accelerates the solvent transport through the hydrogel.

EXPERIMENTS

A new templated-synthesis through "HIPE mixtures" is reported, where the two pre-formed high internal phase emulsions (HIPE) containing the oppositely charged monomers (2-acrylamido-2-methyl-1-propanesulfonic acid and (3-acrylamidopropyl)trimethylammonium chloride) were combined in the same mould, which after polymerization result in the formation of macroporous monoliths of different structures. The resulting frameworks were either copolymer or dual homopolymers in the form of bilayered or mixed porous structures.

FINDINGS

The co- and mixed-amphoteric polyelectrolytes exhibit 'anti-polyelectrolyte' behaviour typical of polyampholytes, while the bilayered-structure behaves like a typical polyelectrolyte. Complete and simultaneous removal of both dyes from a dye mixture was observed for the bilayered- and mixed-amphoteric polyelectrolyte, while copoly-ampholyte showed only partial dye adsorption. These results clearly reveal the benefits of a mutual combination of the HIPE-templated structure and the oppositely charged amphoteric nature in one-piece material as a promising avenue toward advanced materials.

Macromolecular complexes of polyampholytes

The macromolecular complexes of random, regular, graft, block and dendritic polyampholytes with respect to transition metal ions, surfactants, dyes, polyelectrolytes, and proteins are discussed in this review. Application aspects of macromolecular complexes of polyampholytes in biotechnology, medicine, nanotechnology, catalysis are demonstrated.

Preparation of the Sodium Alginate-g-(Polyacrylic Acid-co-Allyltrimethylammonium Chloride) Polyampholytic Superabsorbent Polymer and Its Dye Adsorption Property

A polyampholytic superabsorbent polymer (PASAP), sodium alginate-g-(polyacrylic acid-co-allyltrimethylammonium chloride) (SA-g-(PAA-co-PTM)), was prepared by free-radical graft copolymerization and characterized. The polymer exhibited pH-dependent swelling behaviors with extremely high swelling ratios, and was saline tolerant. The dye adsorption properties of SA-g-(PAA-co-PTM) were investigated using methylene blue (MB) as a cationic dye model. It was found that its dye adsorption capacity was significantly affected by the TM content in PASAP and pH of dye solution. The dye adsorption kinetics and isotherm obey the pseudo-second-order kinetic model and the Langmuir isotherm model, respectively, and the adsorption process is chemisorption in nature. In addition, SA-g-(PAA-co-PTM) exhibited high MB adsorption capacities in a wide pH range and reusability in at least five adsorption-desorption cycles, indicating its great application potentials as the adsorbent for dye removals from effluents.

Schizophrenic poly(ε-caprolactone)s: synthesis, self-assembly and fluorescent decoration

Double hydrophilic copolymers PCCL-b-PPIL and their pyrene-modified copolymers showed pH-responsive “schizophrenic” aggregation behaviors.