Extraordinary swelling behavior of poly(AMPS) organogel in solvent/DMSO binary mixed media

Abstract

The present article deals with super-swelling behavior of crosslinked homopolymer of 2-acrylamido-2-methylpropane sulfonic acid, poly(AMPS), in binary mixtures of dimethyl sulfoxide (DMSO) and various polar solvents including water, mono-, and polyhydric alcohols, and amide solvents such as N-methyl pyrrolidone. Extraordinary phase transition sequences including a new unusual swelling phenomenon, referred to as ''overentrant'' swelling, was observed for this polymeric organogel in the solvent/DMSO mixtures. The swelling behaviors were preliminarily explained based on the major interactions involved in the solvation process and dielectric constant of the swelling media. It was established that the ''overentrant'' region of the swelling profiles was progressed with the increase of dielectric constant of the mixed solvent media. The overentrant region was disappeared with partial replacement of AMPS units with acrylic acid. This was taken as an additional practical evidence for a major role of the sulfonic acid as the main interactive group involved in the solvation process. The unusual phase transitions were also explained via a semiquantitative approach based on the Gutmann's acceptor number and donor number values to emphasis on the key effect of dissociation degree of the sulfonic acid group (as a function of the solvent type and composition) on the swelling behaviors.

Effects of swelling on the viscoelastic properties of polyester films made from glycerol and glutaric acid

“…They are composed of amorphous and crystalline regions that cannot dissolve but swell in the presence of solvents because of their network structure. They can be engineered to respond to changes in solvent composition,5–7 pH,8 temperature,9 and salt concentrations10 by changing their molecular composition or altering their polarity or ionic properties through functionalization.…”

“…It is well known that water is important to many medical applications. DMSO is a nontoxic, highly polar organic fluid that is used in anti‐inflammatory, anticancer, and antioxidant therapies 5, 6, 28, 29. Alcohols such as methanol and ethanol have been extensively studied for the production of polymer gels that require high alcohol contents,26 whereas solvents of lower polarity such as hexane and THF show the potential for polymer gels to be used in applications that involve the recovery of organic solvent and oils 20…”

Preparation and gel properties of poly(ether ether ketone) with pendent sulfonimide groups

“…Many researchers have disclosed that different associations of m DMSO– n H 2 O ( m = 1 and 2 and n = 1–3). B‐SPEEK is a polar macromolecule with a high potential of solvation in polar solvents . Among the polymer–solvent interactions engaged here, those involved with the sulfonic acid groups were major.…”

“…Without water, the sulfonyl imide groups from the polymer chains tended to interact with the sulfonyl groups in DMSO via hydrogen bonding and polar interaction to form stable gel networks. A very significant ionic interaction was sulfonate–sulfonate ionic repulsive forces between the polymer chains, which led to the gel network expansion . When water molecules were added to the system, they tended to replace the sulfonimide groups from the polymer chains in the gel; this led to the precipitation of B‐PEEK and the shrinkage of the gel.…”

Swelling behavior and characterization of alcohol-specific superabsorbing gels based on acrylic acid and allyl tetrasodium thiacalix[4]arene tetrasulfonate

“…Although glycerol possesses more hydroxyl group functionality, the reduced swelling capacity can be attributed to its higher viscosity (934 versus 16.03 cP), which limits the solvent diffusion into the polymer particles [25].…”