Reactive polymer zwitterions: Sulfonium sulfonates

Abstract

Sulfonium sulfonate, or sulfothetin, zwitterionic monomers were synthesized by ring-opening of 1,3-propanesultone with dialkyl sulfides containing styrenic or methacrylic moieties. Reversible addition-fragmentation chain-transfer polymerization of these monomers was achieved in water or trifluoroethanol, and the resulting polymers exhibited higher upper critical solution temperatures than the analogous sulfobetaine polymers. Unlike typical polymer zwitterions, these polymeric sulfothetins possess an inherent reactivity that proved tunable based on their chemical structures. This reactivity makes them amenable to post-polymerization modification by nucleophilic dealkylation to rapidly access novel substituted polymers and gels. V C 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 83-92

Forming Sticky Droplets from Slippery Polymer Zwitterions

“…Zwitterionic polymers are recognized widely for their water solubility and ability to reduce interactions with hydrophobes, oil, and proteins, and therefore find applications as low friction surfaces and antifouling coatings . However, tailoring the solubility of polymer zwitterions can actually promote attractive inter‐ and intramolecular dipole–dipole interactions that afford upper critical solution temperature (UCST) behavior in aqueous media . For example, the cloud point temperature of sulfobetaine methacrylamide polymers in water increased markedly, from ≈15 to ≈75 °C, by incremental increases in the number of methylene groups between the ammonium and the sulfonate groups .…”

“…For example, the cloud point temperature of sulfobetaine methacrylamide polymers in water increased markedly, from ≈15 to ≈75 °C, by incremental increases in the number of methylene groups between the ammonium and the sulfonate groups . In another example, styrenic‐based zwitterionic polymers containing sulfonate anions and either ammonium or sulfonium cations were reported to exhibit cloud point temperatures of 48 and 80 °C, respectively, at 0.5 mg mL −1 in pure water . Given the low solubility of these polymers in water, and prior results showing emulsion droplet stabilization using novel polymer zwitterions, we hypothesized that the interzwitterion interactions may induce interdroplet adhesion.…”

“…Heating from room temperature to 50 °C resulted in droplet gelation, coincident with the lower critical solution temperature behavior of the copolymer surfactant . We are unaware of reports demonstrating the preparation of adhesive emulsions from polymers with UCST behavior, and sought to achieve such materials using zwitterionic polymers such as the sulfothetin polymer 3 ( Figure ), which is inherently reactive and possesses remarkably high cloud point temperatures in water . Salt concentration, temperature, polymer concentration, and polymer molecular weight were varied to discern the influence of each factor on interdroplet interactions.…”

“…Three polymers zwitterions having different cloud point temperatures, namely, methacrylic sulfobetaine 1 , styrenic sulfobetaine 2 , and novel styrenic sulfothetin 3 (Figure a), were investigated in solution and at the oil–water interface of emulsion droplets to determine their ability to modulate interdroplet interactions in response to chemical and environmental triggers. Polymer 1 was selected due to its prevalence in the literature and commercial availability of the monomer, although its high water solubility limits intra‐ and intermolecular interactions.…”

“…Polymer 1 was selected due to its prevalence in the literature and commercial availability of the monomer, although its high water solubility limits intra‐ and intermolecular interactions. For example, at room temperature and molecular weights <50 kDa, polymer 1 is water‐soluble at 1 mg mL −1 (Figure S1, Supporting Information) and possesses cloud points ranging from 15 to 40 °C at 10 mg mL −1 . Styrene‐based zwitterionic polymers 2 and 3 were selected for their relative hydrophobicity and higher cloud points, while polymer 3 provides an additional feature of inherent reactivity .…”