Tuning polymer properties of non-covalent crosslinked PDMS by varying supramolecular interaction strength

• Published in: Polymer chemistry Vol. 11; no. 16; pp. 2847 - 2854
• Main Authors: Lamers, Brigitte A. G, l czkowski, Marcin L, Wouters, Fabian, Engels, Tom A. P, Meijer, E. W, Palmans, Anja R. A
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 28.04.2020
• Subjects: Backbone; Benzene; Bond strength; Bonding strength; Brittle materials; Compressive strength; Covalence; Crosslinking; Elastomers; Hydrogen bonding; Hydrogen embrittlement; Material properties; Mechanical measurement; Networks; Polydimethylsiloxane; Polymer chemistry; Polymers; Pressure molding; Room temperature; Silicone resins; Solvation; Sustainable materials; Temperature dependence; Time dependence
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/d0py00139b

Non-covalently crosslinked polymeric networks are promising materials towards sustainable and recyclable plastics. Here, we present the post-functionalization of poly(dimethyl siloxane) (PDMS) with supramolecular moieties, attached as grafts to the PDMS backbone, to obtain recyclable PDMS networks. We select three different supramolecular motifs that differ in interaction strength and investigate how these differences affect the dynamic behavior of the networks. The introduction of dinitrohydrazones (hydz), which afford weak supramolecular interactions by π-stacking, resulted in a viscous material at room temperature. Stronger self-association was achieved by the introduction of benzene-1,3,5-carboxamides (BTAs) and ureidopyrimidinones (UPys), which self-assemble via triple and quadruple hydrogen bonding, respectively. This resulted in a thermoplastic elastomeric material for BTA-based PDMS and brittle materials for Upy-based PDMS. Time- and temperature-dependent mechanical measurements reveal that the dynamic nature of the supramolecular bonds becomes slower upon increasing the interaction strength. The polymers are fully recyclable by solvation or compression molding without the loss of material properties. Thereby, by using one linear PDMS backbone, we demonstrate how fundamentally different material properties are obtained by changing the supramolecular interaction strength and type of non-covalent crosslinks. These molecular insights broaden the scope and application of PDMS-based sustainable materials. Linear polydimethylsiloxane (PDMS) is crosslinked by supramolecular grafts to obtain materials with strikingly different mechanical properties by tuning the strength of the non-covalent interactions.