Network reorganization in cross-linked polymer/silica composites based on exchangeable dynamic covalent carbon–carbon bonds

• Published in: Polymer (Guilford) Vol. 177; pp. 10 - 18
• Main Authors: Kosuge, Takahiro, Aoki, Daisuke, Otsuka, Hideyuki
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 26.08.2019
• Subjects: Cross-linked polymers; Dynamic covalent chemistry; Electron paramagnetic resonance spectroscopy; Polymer reactions; Polymer/silica composites; Polymer/silica composites; Dynamic covalent chemistry; Electron paramagnetic resonance spectroscopy; Cross-linked polymers; Polymer reactions
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2019.05.046

Diarylbibenzofuranone (DABBF), which contains an exchangeable dynamic covalent carbon–carbon bond was introduced into the polymer or silica domains of two series of polymer/silica composites with a network structure in order to investigate the correlation between the structural reorganization and the location of the DABBF units in these polymer/silica composites. The thermally induced structural reorganization behavior of the two polymer/silica composites was investigated by optical microscopy, dynamic mechanical analysis, and variable-temperature electron paramagnetic resonance spectroscopy. The thus obtained results revealed that the cross-linked polymer/silica composites that contain DABBF units in the polymer domain exhibit network reorganization, and that the efficiency of the network reorganization increases with the molecular weight between the cross-linking points composed of silica domains. Conversely, the cross-linked composite that contains the DABBF units in the silica domains does not show a network reorganization, as the densely cross-linked silica structure prevents the bond exchange reactions of the DABBF units. In their entirety, these results clearly indicate that the incorporation of dynamic covalent linkages in the high mobile polymer domain of cross-linked polymers is advantageous for structural reorganization, which affords a new guiding principle for the design of dynamic-covalent-chemistry-based materials. [Display omitted] •A series of cross-linked polymer/silica composites were prepared.•The composites contain exchangeable dynamic covalent carbon–carbon bonds.•Thermal structural reorganization of the composites was investigated.•The reorganizability depends on the mobility of dynamic covalent linkages.