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CB[n]-hybrid materials
1
We reported a class of microcapsules prepared in a single step using a microdroplet platform, combining the advantages of microfluidic drop-lets and supramolecular host-guest chemistry with quantitative loading efficiency. The ability of CB[8] to act as a supramolecular “handcuff” was exploited by modifying gold nanoparticles (AuNPs) and water-soluble copolymers with complementary functionalities, thereby achieving a controlled dispersion of AuNPs in a polymer network held together by CB[8].
2
Inspired by biological systems, we reported a supramolecular polymer–colloidal hydrogel (SPCH) composed of 98 wt % water that can be readily drawn into uniform
(∼6-μm thick) “supramolecular fibers” at room temperature. Functionalised polymer-grafted silica nanoparticles, a semicrystalline hydroxyethyl cellulose derivative, and CB[8] undergo aqueous self-assembly at multiple length scales to form the SPCH facilitated by host–guest interactions at the molecular level and nanofibril formation at colloidal-length scale. The fibers exhibit a unique combination of stiffness and high damping capacity (60–70%), the latter exceeding that of even biological silks and cellulose-based viscose rayon.
3
Nanocomposite hydrogels were prepared by combining polymer brush-modified ‘hard’ cellulose nanocrystals (CNC) and ‘soft’ polymeric domains, and bound together by cucurbit[8]uril (CB[8]) supramolecular crosslinks, which allow for dynamic host–guest interactions. The resulting supramolecular nanocomposite hydrogels combine three important criteria: high storage modulus (G′ > 10 kPa), rapid sol–gel transition (<6 s), and rapid self-healing even upon aging for several months, as driven by balanced colloidal reinforcement as well as the selectivity and dynamics of the CB[8]. This combination of properties for stiff and self-healing hydrogel materials offers new approaches for the formation of advanced dynamic materials from renewable sources.
4
We enhanced the stiffness of CB[8]-based hydrogels by introducing inorganic nanowires (NWs) into the supramolecular networks. The gel structure can be effectively enhanced by the framework supporting effects of cerous phosphate NWs and additional hydrogen bonding interactions between the NWs and the guest functionalised polymers. The high aspect ratio NWs serve as a “skeleton” for the network providing extra physical crosslinks, resulting in a single continuous phase hybrid supramolecular network with improved strength, presenting a general approach to reinforce soft materials
5
Although Graphene (GR)-based polymer nanocomposites can be manufactured at a large scale, processing limitations result in poor control over the homogeneity of hydrophobic GR sheets in the matrices. Such processes often result in difficulties controlling stability and avoiding aggregation, therefore eliminating benefits that might have otherwise arisen from the nanoscopic dimensions of GR. We utilised CB[8]-mediated host–guest chemistry to obtain supramolecular hydrogels consisting of uniformly distributed GR and guest-functionalised macromolecules. The resultant GR hydrogels show superior bioelectrical properties over identical systems produced without CB[8].
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