Role of Labile Cross-Links in the Behavior of Water-Soluble Polymers

Abstract

The labile crosslinks (herein called "liaisons"), involving noncovalent and/or reversible covalent interactions, that arise between polymer chains when they come into contact, play an important part in the solution behavior of water-soluble polymers. Three cases are discussed in this paper: (1) a simple homopolymer alone in solution, where intrachain liaisons are the so-called "long-range interactions" which influence the conformational size of the molecule; (2) copolymers with a minor content of a comonomer unit which associates by hydrophobic or other interactions, where the application of liaison theory to two types of hydrophobically-associating copolymers -poly(vinyl acetate-co-vinyl alcohol), and alkyl-substituted hydroxyethylcellulose -leads to the establishment of a scale of free energies of hydrophobic-bonding between alkyl chains which is linear with chain length for the range n = 1 to 16; (3) cosolute-binding systems, where extra liaisons may arise from associations between the bound cosolute molecules.The aim of this paper is to show how the behavior of water-soluble polymers -especially their conformational size, their precipitability and phase-separation behavior, and their rheology -is affected by the labile crosslinks that arise between their chains when they come into contact. For convenience and brevity, these labile crosslinks will be called liaisons throughout the rest of the paper. Characteristics of LiaisonsA liaison is taken to be formed wherever there is a contact either between two distantly-connected parts of the same polymer chain ("intrachain") or between parts of two different polymer chains

Thermoresponsive isopropylacrylamide-vinylpyrrolidone copolymer by radiation polymerization

“…The variation of the equilibrium swelling change in the equilibrium water content by the temperature) was observed with the poly(NVP) ratio by the medium temperature is given in Fig- The cloud point measurements with the aqueous poly(NVP) solutions also gave theta temperature values above the boiling point of water. 31,32 Therefore, the observed thermoresponsive behavior poly(NVP) gel in Figure 1 was also supported by the related literature. In the light of the findings in Figure 1, it is normally expected that the gel which will be produced by the copolymerization of NIPAM and NVP will possibly have higher equilibrium water contents at low temperatures relative to that of the poly(NIPAM) gel due to its NVP-based structure and will possibly exhibit a sharper equilibrium swelling content change by the temperature relative to poly(NVP) due to its NIPAM-based structure.…”

Electrochemical, spectroscopic, and thermal studies on interactions of linear poly(acrylic acid) with uranyl ions in aqueous solutions

“…Poly(acrylic acid) (PAA) is a polyelectrolyte containing hydrophilic carboxyl groups in every repeating unit. The presence of carboxylate ions along the polymeric chain ensures the possibility of forming polycomplexes with positively charged moieties and metal ions, the latter being coordinated to one or more COO − groups 6, 7. The stability of these polycomplexes depends on various factors, such as the polycomplex preparation conditions, the structure of the polymer and/or low‐molecular‐weight species, the concentrations of the components, the temperature, the nature of the solvent, and the pH.…”

Factors affecting the complexation of polyacrylic acid with uranyl ions in aqueous solutions: A luminescence study

“…Poly(acrylic acid) (PAA) is the simplest analog of weak polyelectrolytes, which can be used as flocculant in water treatment 6, 7. Various types of small molecules such as metal ions are complexed to PAA and its derivatives containing hydrophilic carboxyl groups 8. On the other hand, PAA is used as the water‐soluble chelating polymer because many comparable data on binding properties of PAA have been published in literature.…”