Molecular Design of Hairy Nanocrystals for Elastomeric Reinforcement

The size of β-sheet nanocrystals self-assembled from β-alanine trimers grafted on polyisobutylene rubber can be controlled and this nanocrystal size affects the morphology of the elastic matrix and thereby the material’s macroscopic elastic properties. The β-sheet crystal size is tailored by altering the density of hydrocarbon chains tethered at the nanocrystal surfaces. Results from TEM, Small Angle X-ray Scattering, and Small Angle Neutron Scattering characterizations of the morphology demonstrate that increasing the density of chain grafting at the crystalline nanodomain surface can sharply limit the nanodomain growth in the direction of hydrogen-bonding in the crystals. The nanocrystal size, in turn, impacts the gradient in chain stretching away from the crystal surface, and the macroscopic volume fraction of unperturbed chains.