ABC Heterotelechelic Associative Polyelectrolytes. Rheological Behavior in Aqueous Media

Abstract

A polystyrene-poly(sodium acrylate)-poly(n-butyl methacrylate) (PS-PANa-PnBMA) ABC triblock copolymer was synthesized by sequential anionic polymerization and modification of the poly-(tert-butyl acrylate) middle block by selective hydrolysis and neutralization to its ionic functions. Because of the fact that both outer hydrophobic blocks are very short comparable to the middle one, this polymer can be viewed as a "heterotelechelic" polyelectrolyte. The rheological behavior of the PS-PANa-PnBMA aqueous solutions was explored by steady state and oscillatory shear flow measurements. Dilute solutions (c < 1 wt %) exhibit very high viscosity, showing that these kinds of polymers can be used as effective thickeners. This behavior is attributed to the formation of a transient network constituted from PS and/ or PnBMA physical cross-links interconnected by stretched polyelectrolyte chains. An unusual observation is that the viscosity of the system seems to be invariant over a wide temperature range. Finally, the differences between heterotelechelic and telehelic polyelectrolytes of the type PS-PANa-PS are also discussed.

Rheology of Block Polyelectrolyte Solutions and Gels: A Review

“…The PS blocks were quite short, 23 monomer units, and the structures formed in solution appeared to be at equilibrium despite the experimental temperature below the glass transition temperature, T g , of PS. 23 G′ and G′′ were found to be approximately independent of ω for c g 0.4 wt %, indicating that the PS-PANa-PS was an elastic gel. Decreasing the degree of ionization of the PAA block (i.e., using a more acidic solution) decreased the storage modulus, but the solution remained a gel with G′ independent of ω.…”

“…When the polyelectrolyte midblock is highly charged, the formation of loops is unfavorable, and more bridges are formed between micelles, creating large aggregates. 23,24 These larger structures bring about interesting rheological behavior, including gel formation at very low polymer concentrations.…”

“…An as example, poly-(sodium acrylate), PANa, the sodium salt of PAA, was used in a PS-PANa-PS block polyelectrolyte studied by Tsitsilianis et al 22, 23 The pH of the solutions was not reported; however, the PAA was neutralized with NaOH, making the pH dependent on polymer concentration. The PS blocks were quite short, 23 monomer units, and the structures formed in solution appeared to be at equilibrium despite the experimental temperature below the glass transition temperature, T g , of PS.…”

Stimuli responsive associative polyampholytes based on ABCBA pentablock terpolymer architecture

“…Charged associative polymers (also named telechelic polyelectrolytes) have attracted attention in the recent years due to the benefits gained by the presence of electrostatic interactions (beyond the hydrophobic) that influence remarkably the association phenomena as well as the rheological behavior [8][9][10][11][12][13][14][15]. Moreover, these associative polymers can be designed to respond to external stimulus like pH [15][16][17], temperature and ionic strength [18] when weak polyelectrolyte chains are used as the main hydrophilic part of the polymer.…”

Hydrophobically Modified Poly(acrylic acid) Using 3‐Pentadecylcyclohexylamine: Synthesis and Rheology

“…[16] Recently, synthetic and rheological studies on poly(sodium acrylate) end-capped with short polystyrene and poly(butyl methacrylate) blocks have been reported. [17][18][19] In the present paper we report on the design and synthesis of a new hydrophobic compound viz. 3-pentadecylcyclohexylamine from renewable resource materials such as cashew nut shell liquid (CNSL) and demonstrate the synthesis of novel HMPs using this hydrophobic compound.…”