The effects of zwitterionic and anionic charge densities in polymer chains on the viscosity behavior of a pH‐responsive hydrophobically modified ionic polymer

Abstract

Sulfur dioxide, N,N-diallyl-N-carboethoxymethylammonium chloride, and the hydrophobic monomer N,N-diallyl-N-octadecylammonium chloride were cyclocopolymerized in dimethyl sulfoxide using azobisisobutyronitrile (AIBN) as the initiator to afford water-soluble cationic polyelectrolytes (CPE) having a five-membered cyclic structure on the polymeric backbone. The CPE on acidic hydrolysis of the pendent ester groups gave the corresponding cationic acid salts (CAS), which, on treatment with sodium hydroxide, were converted to polybetaines (PB) and anionic polyelectrolytes (APE), as well as polymers PB/APE containing various proportions of zwitterionic (PB) and anionic fractions (APE) in the polymer chain. The solution properties of the CPE, APE, and PB/APE systems containing varying amounts of the hydrophobic monomers in the range 0 -4 mol % were investigated by viscometric techniques. Treating the pH-responsive CAS polymers 4 with different equivalents of NaOH varied the zwitterionic and anionic charge densities in the polymer chain. It was found that the PB/APE polymer with a ratio of 33 : 67 for the zwitterionic and anionic fractions in the polymer chain, respectively, gave the highest viscosity value. The polymers showed that concentration (C* HA ) of around 1 g/dL was required for the manifestation of significant hydrophobic associations.

Structures and Synthesis of Zwitterionic Polymers

“…In fact, it seems that nearly the full spectrum of polymerizable groups suited for radical polymerization has been used to make polyzwitterions in the past, including not only styrenes, vinylpyridines, vinylimidazoles or vinylesters [124], but also rather uncommon polymerizable groups such as dienoic acids [123,124,[131][132][133][134][135][136][137][138][139], vinylcyclopropanes [124,134] or isocyanides [69], and cyclopolymerizing species such as diallylammonium [64,87,88,124,134,[140][141][142][143][144][145][146][147][148][149][150][151][152][153] and closely related divinyl monomers [93,94]. Moreover, a number of monomers confined exclusively to (often alternating) radical copolymerization, such as vinylethers [124,134], fumarates and maleates [124,134,[154][155][156], isobutylenes [157] and ...…”

“…This has resulted in a continuous interest in zwitterionic diallylammonium carboxy-, phosphono-and sulfobetaines (cf. Figure 16, P-68 and P-69) [64,87,88,124,134,[140][141][142][143][144][145][146][147][148][149][150][151][152][153]431,433].…”

“…As the polymerizability of allyl monomers is often low, it has been often improved by alternating copolymerization with sulfur dioxide, SO 2 [134,141,[144][145][146][147]150,153,174,[434][435][436]. Though this approach provides a non-hydrolyzable all-carbon linker between the zwitterionic site and the polymer chain, it is somewhat ambiguous, as the aliphatic polysulfone backbone produced is sensitive to thermal stress and strongly basic conditions by itself.…”

Preparation, characterization and application of zwitterionic polymers and membranes: current developments and perspective

“…For zwitterionic organic polymers, one important characteristic is the solution property of polyelectrolyte or anti‐polyelectrolyte behavior, which mainly depends on such influencing factors as the pH values of the polyelectrolyte solution, the composition of the zwitterionic polymer and the presence or absence of inorganic salts 2, 13. Typically, the solution property of zwitterionic organic polymers is determined by measuring the viscosity of the zwitterionic polymer solutions, which mainly characterizes the inter‐ or intramolecular interactions of zwitterionic polymers 65, 66. When the viscosity of a polymer solution increases with an increase in salt concentration, this type of zwitterionic polymer is considered to exhibit polyelectrolyte behavior.…”

Synthesis, viscosity behavior, and interactions with a surfactant of some amphiphilic copolymers of diallyldimethylammonium chloride and diallyldodecyl‐ or diallyloctadecyl‐ammonium chloride

“…The discovery of the polymerization of N,N ‐diallyl quaternary ammonium salts 1 by Butler and Ingley21, 22 via an intra‐ and intermolecular chain propagation through a five‐membered cyclic structure and subsequently, their copolymerization with sulfur dioxide23 led to the synthesis of an array of linear water‐soluble cationic polyelectrolytes (CPE)24 2 and 3 of tremendous scientific and technological interest. There are reports25–31 that describe the synthesis of associating ionic copolymers prepared by Butler's polymerization technique. Previous kinetic studies32 have indicated that a monomer concentration of 50–65 wt % is required to obtain polymers with high conversion, high molecular weight, and low residual double bonds.…”