Thermo-associative Behavior of Poly (4-Vinylpyridine)-g- poly(ethylene oxide) [p4vp-poe] Copolymers

Abstract

Poly(4-vinylpyridine) (P4VP) consists of organic macromolecules that do not dissolve in water. However, modifying these polymers by incorporating polyethylene oxide (PEO) side chains results in novel water-soluble copolymers. The attachment of PEO chains to the P4VP backbone significantly enhances its affinity for water. A distinctive feature of PEO is its decreasing solubility in water as temperature rises. In this study, we examine whether this thermal response is preserved in P4VP-PEO copolymers, leading to their thermoassociative behavior. Monomethyl polyethylene oxide (molecular weight: 6000 g/mol) undergoes functionalization via tosylation. The resulting tosylated PEO is then employed in the quaternization process of P4VP. The rheological properties of the synthesized P4VP-6000-Ts copolymer solutions are analyzed using viscometry. Initial findings suggest a promising thermoassociative system. The variation in reduced viscosity depends on polymer concentration, defining three key concentration regions: C < C*, C = C*, and C > C*.  At C*, the influence of temperature on reduced viscosity becomes evident. A sharp decline in viscosity is directly correlated with the self-association behavior of PEO chains at elevated temperatures.