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Temperature-sensitive behaviour of poly(glycidol)-b-poly(N-isopropylacrylamide) block copolymers

Temperature-sensitive poly(glycidol)-b-poly(N-isopropylacrylamide) block copolymers (PGl55PNIPAAmy) were synthesised and their aqueous solutions investigated by different methods including differential scanning calorimetry (DSC), UV-VIS spectroscopy as well as dynamic and static light scattering. The cloud point temperature (T c) depended on the composition of the investigated block copolymers and increased with decreasing length of the PNIPAAm block in PGl55PNIPAAmy copolymers. In contrast, the enthalpy of phase separation of PNIPAAm segments measured by DSC decreased with decreasing length of the PNIPAAm block in the polymer. These findings can be correlated with the behaviour of homo-PNIPAAm with similar molecular weights indicating that the influence of PGl on the local environment and phase separation of PNIPAAm chains is similar to the influence observed for PNIPAAm chains bearing different low molecular weight end group. Using DLS measurement, it was shown that the aggregation process depended on the PGl/PNIPAAm block ratio. If the PGl/PNIPAAm ratio was low, stable core-shell aggregates were formed. In contrast, the tendency to formation of large unstable, loose aggregates was observed for copolymers with high PGl/PNIPAAm ratio.

Authors:   Sebastian Mendrek, Aleksandra Mendrek, Hans-Juergen Adler, Andrzej Dworak, Dirk Kuckling
Journal:   Colloid & Polymer Science
Year:   2010
DOI:   10.1007/s00396-010-2203-0
Publication date:   11-Mar-2010
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