Conformational transition in poly[4-(1,1,3,3-tetramethylbutyl)phenyl methacrylate] and poly(4-tert-butylphenyl methacrylate) in dilute solutions |
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Authors: | Carmen Sarabia Deodato Radic Ligia Gargallo |
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Affiliation: | Departamento de Fisico Química – Instituto Ciencias Químicas Pontificia Universidad Católica de Chile, Casilla 114-D, Santiago — Chile |
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Abstract: | Temperature dependence of viscosity data and refractive index increment was investigated on two polymers: poly[4-(1,1,3,3-tetramethylbutyl)phenyl methacrylate] ( 1a ) and poly(4-tert-butylphenyl methacrylate) ( 1b ) in dilute solution. A discontinuity in intrinsic viscosity was observed over a narrow temperature range. From this behaviour it was possible to visualize sharp changes of unperturbed dimensions (Kθ) and thermodynamic parameters (B). This phenomenon can be accounted for by assuming conformational changes of the chain in the chosen solvent in a specific temperature range. These changes can be also observed by discontinuities in refractive index increments dn/dc. In the case of 1b the conformational change disappears on addition of a polar solvent (CHCl3). |
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