High-Strength, Healable, Supramolecular Polymer Nanocomposites

Abstract

A supramolecular polymer blend, formed via π-π interactions between a π-electron rich pyrenyl end-capped oligomer and a chain-folding oligomer containing pairs of π-electron poor naphthalene-diimide (NDI) units, has been reinforced with cellulose nanocrystals (CNCs) to afford a healable nanocomposite material. Nanocomposites with varying weight percentage of CNCs (from 1.25 to 20.0 wt %) within the healable supramolecular polymeric matrix have been prepared via solvent casting followed by compression molding, and their mechanical properties and healing behavior have been evaluated. It is found that homogeneously dispersed films can be formed with CNCs at less than 10 wt %. Above 10 wt % CNC heterogeneous nanocomposites were obtained. All the nanocomposites formed could be rehealed upon exposure to elevated temperatures although, for the homogeneous films, it was found that the healing rate was reduced with increasing CNC content. The best combination of healing efficiency and mechanical properties was obtained with the 7.5 wt % CNC nanocomposite which exhibited a tensile modulus enhanced by as much as a factor of 20 over the matrix material alone and could be fully rehealed at 85 °C within 30 min. Thus it is demonstrated that supramolecular nanocomposites can afford greatly enhanced mechanical properties relative to the unreinforced polymer, while still allowing efficient thermal healing.

Nano-building block based-hybrid organic–inorganic copolymers with self-healing properties

“…[28][29][30] In our sample, the ionic bonds at the hybrid interface are more labile and have the ability to be broken and reformed compared with all the covalent bonds of the main chain; the re-distribution of the ionic bonds is likely the major reason for the observed behavior. To highlight the dynamic nature of the cross-link nodes, a piece of material made of n-BuA copolymerized with 6 wt% of [(BuSn) 12 (Fig.…”

Hybrid materials based on polyethylene and MCM-41 microparticles functionalized with silanes: Catalytic aspects of in situ polymerization, crystalline features and mechanical properties

“…Examples in literature exhibit significant improvements in mechanical, electrical, biocidal and thermal properties [1][2][3][4][5][6][7], which are difficult to be achieved using conventional fillers [8,9]. An aspect of significant impact, mainly in weight and cost, is the low reinforcement loadings required (typically inferior to 8 wt.%) to attain a noteworthy enhancement in properties.…”

Healable supramolecular polymer solids

“…Fox et al investigated this issue by combining a previously studied supramolecular  stacking polymer system (vide supra) [101], composed of a telechelic building block end-capped with π-electron rich pyrenyl end-groups ( Figure 12, LPD-2) and a second oligomer comprising π-electron poor naphthalene-diimide groups ( Figure 11, FPA-2) with cellulose nanocrystals (CNCs) [107]. CNCs, which can be extracted by acid hydrolysis from virtually all cellulosic biomaterials, are rod-like particles with a width of 5-20 nm and a length of 100-5000 nm [108,109].…”

“…In the rubbery regime (20 °C), the tensile storage modulus increased the ureidopyrimidone (UPy) motif [113]. Building on the  bonded supramolecular polymers introduced by Fox et al [107],…”