Yuchao Wu

Photoresponsive Hybrid Raspberry-Like Colloids Based on Cucurbit[8]uril Host–Guest Interactions†

Hybrid raspberry-like colloids (HRCs) were prepared by employing cucurbit[8]uril (CB[8]) as a supramolecular linker to assemble functional polymeric nanoparticles onto a silica core. The formed HRCs are photoresponsive and can be reversibly disassembled upon light irradiation. This facile supramolecular approach provides a platform for the synthesis of colloids with sophisticated structures and properties.

Interfacial assembly of dendritic microcapsules with host–guest chemistry

The self-assembly of nanoscale materials to form hierarchically ordered structures promises new opportunities in drug delivery, as well as magnetic materials and devices. Herein, we report a simple means to promote the self-assembly of two polymers with functional groups at a water-chloroform interface using microfluidic technology. Two polymeric layers can be assembled and disassembled at the droplet interface using the efficiency of cucurbit[8]uril (CB[8]) host-guest supramolecular chemistry. The microcapsules produced are extremely monodisperse in size and can encapsulate target molecules in a robust, well-defined manner. In addition, we exploit a dendritic copolymer architecture to trap a small hydrophilic molecule in the microcapsule skin as cargo. This demonstrates not only the ability to encapsulate small molecules but also the ability to orthogonally store both hydrophilic and hydrophobic cargos within a single microcapsule. The interfacially assembled supramolecular microcapsules can benefit from the diversity of polymeric materials, allowing for fine control over the microcapsule properties.

Microfluidic Droplet-Facilitated Hierarchical Assembly for Dual Cargo Loading and Synergistic Delivery

Bottom-up hierarchical assembly has emerged as an elaborate and energy-efficient strategy for the fabrication of smart materials. Herein, we present a hierarchical assembly process, whereby linear amphiphilic block copolymers are self-assembled into micelles, which in turn are accommodated at the interface of microfluidic droplets via cucurbit[8]uril-mediated host–guest chemistry to form supramolecular microcapsules. The monodisperse microcapsules can be used for simultaneous carriage of both organic (Nile Red) and aqueous-soluble (fluorescein isothiocyanate-dextran) cargo. Furthermore, the well-defined compartmentalized structure benefits from the dynamic nature of the supramolecular interaction and offers synergistic delivery of cargos with triggered release or through photocontrolled porosity. This demonstration of premeditated hierarchical assembly, where interactions from the molecular to microscale are designed, illustrates the power of this route toward accessing the next generation of functional materials and encapsulation strategies.

Bioinspired supramolecular fibers drawn from a multiphase self-assembled hydrogel

Significance Fiber materials have great impact on our daily lives, with their use ranging from textiles to functional reinforcements in composites. Although the manufacturing process of manmade fibers is potentially limited by extensive energy consumption, spiders can readily spin silk fibers at room temperature. Here, we report a class of material that is based on a self-assembled hydrogel constructed with dynamic host–guest cross-links between functional polymers. Supramolecular fibers can be drawn from this hydrogel at room temperature. The supramolecular fiber exhibits better tensile and damping properties than conventional regenerated fibers, such as viscose, artificial silks, and hair. Our approach offers a sustainable alternative to current fiber manufacturing strategies. Inspired by biological systems, we report 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. Functionalized polymer-grafted silica nanoparticles, a semicrystalline hydroxyethyl cellulose derivative, and cucurbit[8]uril 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. The remarkable damping performance of the hierarchically structured fibers is proposed to arise from the complex combination and interactions of “hard” and “soft” phases within the SPCH and its constituents. SPCH represents a class of hybrid supramolecular composites, opening a window into fiber technology through low-energy manufacturing.

Supracolloidal Architectures Self-Assembled in Microdroplets.

We demonstrate a novel method for the formation of a library of structured colloidal assemblies by exploiting the supramolecular heteroternary host-guest interaction between cucurbit[8]uril (CB[8]) and methyl viologen- and naphthalene-functionalised particles. The approach is dependent upon compartmentalisation in microdroplets generated by a microfluidic platform. Though the distribution of colloidal particles encapsulated within each microdroplet followed a Poisson distribution, tuning the concentration of the initial colloidal particle suspensions provided some level of control over the structure of the formed colloidal assemblies. This ability to direct the assembly of complementarily-functionalised colloids through a supramolecular interaction, without the need for complex modification of the colloidal surface or external stimuli, presents an exciting new approach towards the design of structured colloidal materials with the potential to produce many challenging structures.

Hybrid organic-inorganic supramolecular hydrogel reinforced with CePO4 nanowires

We report a method to enhance the stiffness in the rheological yield strain of cucurbit[8]uril (CB[8])-based hydrogels by introducing inorganic nanowires (NWs) into the supramolecular networks. The supramolecular hydrogel is comprised of methylviologen-functionalised poly(vinyl alcohol) (PVA-MV), hydroxyethyl cellulose with naphthyl moieties (HEC-Np) and CB[8] macrocyclic hosts. 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 PVA-MV/HEC-Np 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.

Cucurbit[8]uril‐Regulated Colloidal Dispersions Exhibiting Photocontrolled Rheological Behavior

In situ photocontrol over shear-thickening of condensed colloidal dispersions is of paramount importance in a wide range of applications including process technology and photorheological fluids. Its development and practicability, however, are hampered by the lack of well-designed photoresponsive systems. Here, a colloidal suspension whose rheological behavior is readily switchable between shear-thinning and shear-thickening using an external light stimulus is reported. This smart colloidal solution contains hybrid raspberry-like colloids prepared by employing cucurbit[8]uril as a supramolecular linker to assemble functional Fe3 O4 nanoparticles onto a silica core. The formed raspberry colloids are photoresponsive and can be reversibly disassembled under UV irradiation.

Correction: Hybrid organic–inorganic supramolecular hydrogel reinforced with CePO4 nanowires

Correction for ‘Hybrid organic–inorganic supramolecular hydrogel reinforced with CePO4 nanowires’ by Chenyan Liu et al., Polym. Chem., 2016, 7, 6485–6489.

Research data supporting [Mining 2:2 Complexes from 1:1 Stoichiometry: Formation of Cucurbit[8]urilDiarylviologen Quaternary Complexes Favored by Electron-Donating Substituents]

NMR, ITC, Mass, CCS calculation, and UV-Vis data to support the demonstration of 2:2 binding mode of CB[8]-diarylviologen complexes

Research data supporting “Surface-bound cucurbit[8]uril catenanes on magnetic nanoparticles exhibiting molecular recognition”

NMR of MV-SIlane and MV-silane@CB[8], ITC of MV-silane@CB[8], MS of three peptide sequences.