@misc{zharinova_waterblown_polyurethane_2016, 
author={Zharinova, E., Heuchel, M., Weigel, T., Gerber, D., Kratz, K., Lendlein, A.},
title={Water-Blown Polyurethane Foams Showing a Reversible Shape-Memory Effect},
year={2016},
howpublished = {journal article},
doi = {https://doi.org/10.3390/polym8120412},
abstract = {Water-blown polyurethane (PU) foams are of enormous technological interest as they are widely applied in various fields, i.e., consumer goods, medicine, automotive or aerospace industries. The discovery of the one-way shape-memory effect in PU foams provided a fresh impetus for extensive investigations on porous polymeric actuators over the past decades. High expansion ratios during the shape-recovery are of special interest when big volume changes are required, for example to fill an aneurysm during micro-invasive surgery or save space during transportation. However, the need to program the foams before each operation cycle could be a drawback impeding the entry of shape-memory polymeric (SMP) foams to our daily life. Here, we showed that a reversible shape-memory effect (rSME) is achievable for polyurethane water-blown semicrystalline foams. We selected commercially available crystallizable poly(ε-caprolactone)-diols of different molecular weight for foams synthesis, followed by investigations of morphology, thermal, thermomechanical and shape-memory properties of obtained compositions. Densities of synthesized foams varied from 110 to 180 kg∙m−3, while peak melting temperatures were composition-dependent and changed from 36 to 47 °C, while the melting temperature interval was around 15 K. All semicrystalline foams exhibited excellent one-way SME with shape-fixity ratios slightly above 100% and shape-recovery ratios from the second cycle of 99%. The composition with broad distribution of molecular weights of poly(ε-caprolactone)-diols exhibited an rSME of about 12% upon cyclic heating and cooling from Tlow = 10 °C and Thigh = 47 °C. We anticipate that our experimental study opens a field of systematic investigation of rSMEs in porous polymeric materials on macro and micro scale and extend the application of water-blown polyurethane foams to, e.g., protective covers with zero thermal expansion or even cushions adjustable to a certain body shape.},
note = {Online available at: \url{https://doi.org/10.3390/polym8120412} (DOI). Zharinova, E.; Heuchel, M.; Weigel, T.; Gerber, D.; Kratz, K.; Lendlein, A.: Water-Blown Polyurethane Foams Showing a Reversible Shape-Memory Effect. Polymers. 2016. vol. 8, no. 12, 412. DOI: 10.3390/polym8120412}}