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The influence of structural constraints on the relaxation dynamics of three polyurea networks with a varying degree of crosslinking, has been studied by means of a thorough analysis of broadband dielectric spectroscopy measurements. Two different relaxation processes are observed, namely, a fast process involving the soft poly(propylene oxide) chains, and a slower and much broader process associated with the immediate surroundings of the hard crosslinkers. Microphase separation in soft and hard domains characterizes the systems in the presence of hydrogen bonding. In this case, different confinement conditions are explored by varying the soft chain length; overall, so called “adsorption” effects dominate. With respect to both cooperativity and the rearrangement energy threshold in fast relaxation, it is found that the enhancement of configurational constraints is similar to cooling, but only on qualitative …
Royal Society of Chemistry
Publication date: 
1 Jan 2018

Nerea Sebastián, Christophe Contal, Antoni Sánchez-Ferrer, Marco Pieruccini

Biblio References: 
Volume: 14 Issue: 38 Pages: 7839-7849
Soft matter