EBE and BEB triblock copolymers were prepared and characterized. Microphase separation in the melt state was studied, and the results combined with those for EB and BEB copolymers reported previously. The microphase separation temperature (MST) was determined from the temperature dependence of SAXS. There was a large difference in MST between the diblock and triblock copolymers as expected from theory. The Flory‐Huggins parameter (χ) was independent of block architecture for all three series provided that the E block lengths in the EBE copolymers exceeded 65.
High-molar-mass poly[oxymethylene-oligo(oxyethylene)] (POMOE, oxymethylene-linked PEG400) was prepared by inclusion of a multifunctional alcohol in the polycondensation recipe. Approximate values of the critical concentration for gelation were determined. Branching in samples prepared at lower-than-critical concentrations was confirmed by comparison of molar masses determined by gel-permeation chromatography and static light scattering. Melt flow indices confirmed an increase in viscosity. Differential scanning calorimetry and dynamic mechanical thermal analysis were used to determine glass-transition and melting temperatures of the polymers and of mixtures of the polymers with lithium perchlorate. Conductivities of polymer-salt mixtures were measured. Comparison of results for branched and linear polymers indicated no significant difference in properties, including conductivity, apart from a decrease in melt flow index.
We report the results of a SANS study into the structure of the adsorbed layers formed at the interface in a dilute perfluorodecalinin-water emulsion by five short chain diblock copolymers of oxyethylene (OE) and oxybutylene (OB). The results are discussed in the context of the Marques-Joanny-Leibler scaling description of block copolymer adsorption from selective solvents. The volume fraction profiles are best described by parabolic and, to a lesser extent, Gaussian functional forms. On increasing the temperature the buoy segments of one copolymer were found to contract toward the surface, giving rise to profiles that were more block-like in accordance with the mean-field predictions of Wijmans and Zhulina.
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