Association properties of diblock copolymers of ethylene oxide and 1,2-butylene oxide in aqueous solution. Copolymers with oxyethylene-block lengths in the range 100-400 chain units
W. Mingvanish et al., Association properties of diblock copolymers of ethylene oxide and 1,2-butylene oxide in aqueous solution. Copolymers with oxyethylene-block lengths in the range 100-400 chain units, J PHYS CH B, 103(51), 1999, pp. 11269-11274
Copolymers E96B18, E184B18, E315B17, and E398B19 (E = oxyethylene unit, B =
oxybutylene unit) were synthesized and characterized by gel permeation chr
omatography (for distribution width) and C-13 NMR spectroscopy (for absolut
e molar mass and composition). Dynamic and static light scattering was used
to determine micellar properties in dilute aqueous solution at three tempe
ratures (25, 40, and 50 degrees C): that is, hydrodynamic radius and hydrod
ynamic expansion factor, mass-average molar mass, and thermodynamic expansi
on factor. At a given temperature, the values of the radii and expansion fa
ctors increased as E-block length was increased, whereas values of the mice
lle association number decreased. The tube-inversion method was used to def
ine the mobile-immobile (hard gel) phase boundary. At room temperature (20
degrees C), hard gels were formed in the concentration range 3.5-8 wt % cop
olymer depending on E-block length, the lowest value being for the copolyme
r with the longest E block (E398B19).