Abstract
Poly(acrylic acid)-graft-poly(ethylene oxide) (PAA-g-PEO) in aqueous solutions shows one fast and one slow relaxation mode in dynamic light scattering (DLS), but the mixture of PAA and PEO (PAA/PEO) in aqueous solution only has a single fast mode. The effects of pH, polymer concentration, and salt concentration on these two modes have been investigated using laser light scattering (LLS), viscometry, and rheological measurements. Our results showed that the hydrogen bonding between carboxylic group and ether oxygen led to the formation of large complexes among PAA-g-PEO chains, which were absent between PAA and PEO chains in PAA/PEO aqueous solutions. The addition of formamide can break these interchain complexes because the hydrogen bonding between formamide and PAA segment is stronger than that between PEO and PAA segment. Thermodynamically speaking, the formation of hydrogen bonds among PAA-g-PEO chains leads to a less entropy loss than that between PAA and PEO chains in PAA/PEO aqueous solution, becaus...
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