Attempt toward 1D cross-linked thermoplastic elastomers:: Structure and mechanical properties of a new system

1D cross-linked thermoplastic elastomers could be an interesting class of materials, where the elastomer would be physically cross-linked by the self-association of functional groups forming long supramolecular chains. These materials could present both a high strength (due to the very large functionality of the cross-linking domains) and reversibility at room temperature (due to the intrinsic reversibility of the supramolecular chains). To obtain such materials, poly(dimethylsiloxane)s (PDMS) grafted with hydrogen bonding bis-ureas have been synthesized by modification of amino-functional PDMS. The materials obtained are physically cross-linked at room temperature by aggregation of strongly but reversibly self-associated bis-ureas. PDMS combining high bis-urea content and long polymer chains can undergo high strains and stresses at room temperature, but they can be processed at higher temperature. A wide control of the mechanical properties of the materials has been achieved by adjusting the structure of the polymer (molecular weight, grafting density, nature of the bis-urea). Although 3D cross-linking has been obtained instead of the aimed 1D cross-linking, new thermoplastic elastomers with easily tunable processing temperature and mechanical properties are presented.