Abstract:The specific isobaric heat capacities of poly (methylmethacrylates) (PMMA) having various tacticities were measured by the DSC method within a broad range of temperatures including the glass transition. Glasses with uniform thermal history were used in the measurements and the data were treated by employing a procedure which provided the "thermodynamic" Tg independent of the experimental conditions. The semiquantitative validity of Boyer's empirical relation Tg• Ac~ = const, was confirmed; also it was found that within the limits of experimental accuracy the cp, g values at 298 K and c~,z values at 400 K are independent of the tacticity of the sample.Using the data thus measured and linearized equations representing the dependence of Tg on the content of iso-, syndio-and heterotriads, the Tg values of pure isotactic PMMA and pure syndiotactic PMMA were found to be respectively 315 K and 397 K.
A systematic study of complexation reactions of sulfonated polystyrene ionomers containing up to 5 molar percent of polar chain units with various oil-soluble surfactants is carried out in low-polarity organic solvents. Dipole-dipole attractions of the components lead to the formation of complexes characterized by limiting compositions and an unusual polymer-colloidal morphology of joint clusters and/or micelles. The limiting compositions (cp) for the complexes formed between ionomers and surfactant of the same charge (bis(2-ethylhexy1)suIfosuccinate sodium salt), or nonionic surfactants (primarily aliphatic amines) are equal to 15-30 surfactant molecules per one ionomer salt/acid group on average, with cp depending on the hydrophilic-lypophilic balance of the components, the initial aggregation state of surfactant and the nature of low-polarity solvent. lonomersurfactant complexation is accompanied by disruption of self-contacts of ionomer salt/acid groups, leading to "unfastening" and expansion of the ionomer coils in dilute solution. The "driving force" of the ionomersurfactant complexation and the structure of the resultant complexes are discussed.
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