Mixed solutions of hydrophobically modified graft and block copolymers

• Phase separation temperatures and viscosities of dilute and semidilute aqueous mixtures of hydrophobically modified graft and block copolymers have been studied. The graft copolymer was hydrophobically modified ethyl(hydroxyethyl)cellulose (HM-EHEC), and the block copolymers were hydrophobically modified poly(ethylene glycol) (HM-PEG) with diblock (DB) or triblock (TB) structures, i.e., modified at one or both ends, respectively. For comparison, viscosity measurements were made also on mixtures of TB with HM-HEC, and on systems where one of the polymers was unmodified (i.e. HM-EHEC/PEG or TB/EHEC). All results indicate mixed hydrophobic associations between graft and block copolymers. Moderate viscosity enhancements were found on addition of HM-PEG to HM-EHEC, and the effects were larger for TB than for DB. The viscosity changes were quite sensitive to the concentration of HM-EHEC. (C) 2004 Elsevier B.V. All rights reserved.

Ämnesord

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

Nyckelord

Hydrophobically modified copolymers

Graft copolymer

Block copolymer

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