Macroscopic
supramolecular assembly (MSA) is a new concept of supramolecular
science with an emphasis on noncovalent interactions between macroscopic
building blocks with sizes exceeding 10 Îźm. Owing to a similar
noncovalently interactive nature with the phenomena of bioadhesion,
self-healing, etc. and flexible features in tailoring and designing
modular building blocks, MSA has been developed as a simplified model
to interpret interfacial phenomena and a facile method to fabricate
supramolecular materials. However, at this early stage, MSA has always
been limited to hydrogel materials, which provide flowability for
high molecular mobility to the interfacial binding. The extension
to a wide range of materials for MSA is desired. Herein, we have developed
a strategy of adjusting intrinsic properties (e.g., elastic modulus)
of nonhydrogel materials to realize MSA, which could broaden the material
choices of MSA. Using the widely used elastomer of polyÂ(dimethylsiloxane)
(PDMS) as building blocks, we have demonstrated the elastic-modulus-dependent
MSA of PDMS based on the host/guest molecular recognition between
supramolecular groups of β-cyclodextrin and adamantane. In the
varied elastic modulus range of 0.38 to 3.84 MPa, we obtained the
trend of the MSA probability decreasing from 100% at 0.38 MPa to 0%
at 3.84 MPa. Meanwhile, in situ measurements of interactive forces
between PDMS building blocks have supported the observed assembly
phenomena. The underlying reasons are interpreted with the low-modulus
flexible surfaces favoring for high molecular mobility to achieve
interactions between multiple sites at the interface based on the
theory of multivalency. Taken together, we have demonstrated the feasibility
of directly adjusting the modulus of bulk materials to realize MSA
of nonhydrogel materials, which may provide clues to the fast wet
adhesion and new solutions to the additive manufacture of elastomer
materials.