Blocked Shape Memory Effect in Negative Poisson's Ratio Polymer Metamaterials

Katarzyna Boba, Matteo Bianchi, Greg McCombe, Ruben Gatt, Anselm C. Griffin, Robert M. Richardson, Fabrizio Scarpa*, Ian Hamerton, Joseph N. Grima

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

37 Citations (Scopus)
493 Downloads (Pure)


We describe a new class of negative Poisson's ratio (NPR) open cell PU-PE foams produced by blocking the shape memory effect in the polymer. Contrary to classical NPR open cell thermoset and thermoplastic foams that return to their auxetic phase after reheating (and therefore limit their use in technological applications), this new class of cellular solids has a permanent negative Poisson's ratio behavior, generated through multiple shape memory (mSM) treatments that lead to a fixity of the topology of the cell foam. The mSM-NPR foams have Poisson's ratio values similar to the auxetic foams prior their return to the conventional phase, but compressive stress-strain curves similar to the ones of conventional foams. The results show that by manipulating the shape memory effect in polymer microstructures it is possible to obtain new classes of materials with unusual deformation mechanisms.

Original languageEnglish
Pages (from-to)20319-20328
Number of pages10
JournalACS Applied Materials and Interfaces
Issue number31
Early online date26 Jul 2016
Publication statusPublished - 10 Aug 2016


  • foam
  • metamaterial
  • negative Poisson's ratio
  • polyurethane
  • shape memory


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