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Phase Behavior and Mechanical Properties of Mixed Poly(ethylene glycol) Mono‐Dodecyl Ether Aqueous Solutions
Author(s) -
Yamazaki Ritsuko,
Iizuka Kenichi,
Hiraoka Kazuyuki,
Nose Takuhei
Publication year - 2005
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200400325
Subject(s) - ethylene glycol , materials science , micelle , aqueous solution , phase (matter) , ether , elastic modulus , chemical engineering , polymer chemistry , chemistry , composite material , organic chemistry , engineering
Abstract Summary: The phase behavior and mechanical properties of mixed aqueous solutions of poly(ethylene glycol) mono‐dodecyl ether (C12E25) (the number of ethylene glycol units is about 25) and octa‐(ethylene glycol) mono‐dodecyl ether (C12E8) at 50 wt.‐% of the total concentration (C12E25 + C12E8) have been investigated by means of viscoelastic and thermal measurements and small‐angle X‐ray scattering. The phase behavior as a function of C12E25 composition ( ϕ C12E25 ) was divided into three regions. The C12E8‐rich gel region (0 < ϕ C12E25 < 0.4) showed a hexagonal liquid crystalline phase of cylindrical micelles. The C12E25‐rich gel region (0.8 < ϕ C12E25 < 1) included a body‐centered cubic phase of spherical micelles and the intermediate region (0.4 < ϕ C12E25 < 0.8) with fluidity included disordered one‐phase and two‐phase regions. The cylindrical hexagonal ordered structure was maintained against the incorporation of C12E25 over a wide range of ϕ C12E25 , while the cubic lattice structure easily became unstable on addition of C12E25. The C12E8‐rich gel solution had a lower elastic modulus with a relatively high loss modulus, while the gel in the C12E25‐rich region had a higher modulus and was more elastic with low values of the loss tangent. The stress‐strain curves observed showed that the C12E8 gel had no yield point but demonstrated a very broad peak with no steady flow in the experimental time range, while the C12E25 gel showed a yield point, followed by a steady plastic flow. The C12E25‐rich solution recovered its rheological properties which were distorted by pre‐shear deformation faster than the C12E8‐rich gel did. These findings are discussed in terms of differences in the ordered structure between the cylindrical and spherical micellar gels with mixed shorter and longer corona chains.SAXS profiles of C12E25‐C12E8 aqueous solutions.