Relaxation Processes of Poly(tert-butyl acrylate) Chemically Confined via Hydrogen Bonds

In this work, tailored copolymers of tert-butyl acrylate and acrylic acid (AA) with an ABA type structure were systematically analyzed via dynamic-mechanical analysis with regard to their relaxations, in which the main focus was put on a chemical confinement (cc) mode caused by hydrogen bonds. Four different relaxation modes were detected, whereupon two modes seem to depend on the length of the inner B-block and one on the length of the outer A-blocks. One mode below room temperature could be identified as a secondary relaxation which belongs to the B-block and is most likely induced by a cc. A softening of the polymer corresponding to the glass transition is found near to room temperature and surprisingly shifts to lower temperatures with increasing chain length of the B-block. A second softening of the ABA type copolymers is caused by the AA containing A-blocks and was found at higher temperatures.