Design of auxetic polymer self-assemblies

Alternating copolymers having a double-arrow-like "hard" block and a spring-like "soft" segment have been designed which can in principle self-assembly into two-dimensional supramolecular networks. Molecular-mechanics calculations show that such self-assemblies can be auxetic when the lengths of the block and the segment are carefully chosen, with one metastable supermolecule having one of its six Poisson ratios as negatively large as -11.86. The underlying principle of designing such auxetic self-assembly of copolymers with specified architecture is also given as are the deciding factors such as the packing geometry and the associated lattice energy in achieving the auxeticity. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.