Zwitterionic Ammonium Sulfonate Polymers: Synthesis and Properties in Fluids.

Polymer zwitterions continue to emerge as useful materials for numerous applications, ranging from hydrophilic and antifouling coatings to electronic materials interfaces. While several polymer zwitterion compositions are now well established, interest in this field of soft materials science has grown rapidly in recent years due to the introduction of new structures that diversify their chemistry and architecture. Nonetheless, at present, the variation of the chemical composition of the anionic and cationic components of zwitterionic structures remains relatively limited to a few primary examples. In this article, the versatility of 4-vinylbenzyl sultone as a precursor to ammonium sulfonate zwitterionic monomers, which are then used in controlled free radical polymerization chemistry to afford "inverted sulfobetaine" polymer zwitterions, is highlighted. An evaluation of the solubility, interfacial activity, and solution configuration of the resultant polymers reveals the dependence of properties on the selection of tertiary amines used for nucleophilic ring-opening of the sultone precursor, as well as useful properties comparisons across different zwitterionic compositions.

Polymer Zwitterions with Phosphonium Cations.

Polymer zwitterions are of interest for numerous applications, many of which stem from their antifouling properties when used as hydrophilic coatings. However, the chemical compositions of polymer zwitterions remain limited, with synthetic variants most typically comprising ammonium cations. This manuscript describes the synthesis of novel phosphonium-based zwitterionic monomers, accessed by ring opening of substituted propane sultones with aliphatic and aromatic phosphines, and their polymerization by controlled free radical methods. Interestingly, the resultant polymeric phosphonium sulfonates proved soluble in numerous organic solvents, distinguishing them from the solution properties of more typical hydrophilic polymer zwitterions, with tunable and switchable properties made possible by selection of phosphonium R groups. Block copolymers prepared from these tailored phosphonium sulfonate zwitterions highlight their diverse range of solubility and amenability to aqueous polymer assembly.

Coacervation in polyzwitterion-polyelectrolyte systems and their potential applications for gastrointestinal drug delivery platforms.

Traditionally, complex coacervation is regarded as a process whereby two oppositely charged polyelectrolytes self-assemble into spherical droplets. Here, we introduce the polyzwitterionic complex, "pZC", formed by the liquid-liquid phase separation of a polyzwitterion and a polyelectrolyte, and elucidate a mechanism by which such complexes can assemble using theory and experimental evidence. This system exhibits orthogonal phase behavior-it remains intact in acidic conditions, but disassembles as the pH increases, a process governed by the acid-base equilibria of the constituent chains. We relate the observed phase behavior to physiological conditions within the gastrointestinal tract with a simulation of the gastroduodenal junction, and demonstrate using video microscopy the viability of polyzwitterionic coacervates as technologies for the pH-triggered release of cargo. Such a system is envisaged to tackle imminent problems of drug transport via the oral route and serve as a packaging solution to increase uptake efficiency.