L. Bromberg et M. Temchenko, Self-assembly in aqueous solutions of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide)-b-poly(vinyl alcohol), LANGMUIR, 15(25), 1999, pp. 8633-8639
A novel class of self-assembling amphiphilic polymers is introduced whereby
a Pluronic poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene ox
ide) (PEO-PPO-PEO) triblock copolymer is end-modified by poly(vinyl alcohol
) (PVA). The copolymer is temperature-sensitive in aqueous solutions due to
the temperature-dependent water solubility of PPO. The Pluronic-PVA copoly
mers show a dramatic temperature dependency of their aggregation. The attac
hment of PVA segments to the Pluronic molecule increases its critical aggre
gation temperature. At concentrations of 10% and higher and temperatures ab
ove 10-20 degrees C, the Pluronic-PVA aqueous solutions yield gels. The gel
ation and formation of large aggregates coincide, indicating that the gelat
ion is caused by the formation of aggregates with interpenetrating coronas.
A decline in the power law relaxation exponent of the light scattering is
observed upon gelation, which is due to the nonergodicity of the gels.