2D transition metal carbides and nitrides (MXenes), a class of emerging nanomaterials with intriguing properties, have attracted significant attention in recent years. However, owing to the highly hydrophilic nature of MXene nanosheets, assembly strategies of MXene at liquid–liquid interfaces have been very limited and challenging. Herein, through the cooperative assembly of MXene and amine‐functionalized polyhedral oligomeric silsesquioxane at the oil–water interface, we report the formation, assembly, and jamming of a new type MXene‐based Janus‐like nanoparticle surfactants, termed MXene‐surfactants (MXSs), which can significantly enhance the interfacial activity of MXene nanosheets. More importantly, this simple assembly strategy opens a new platform for the fabrication of functional MXene assemblies from mesoscale (e.g., structured liquids) to macroscale (e.g., aerogels), that can be used for a range of applications, including nanocomposites, electronic devices, and all‐liquid microfluidic devices.

Nanoparticle surfactants (NPSs) assembled at the oil−water interface can significantly lower the interfacial tension and be used to structure liquids. However, to realize the three-dimensional printing of one liquid in another, high-viscosity liquids, for example, silicone oil, have been generally used. Here, we present a simple, low-cost approach to print water in low-viscosity toluene by using a new type of polyelectrolyte surfactant, sodium carboxymethyl cellulose surfactant (CMCS), that forms and assembles at the oil−water interface. The interfacial activity of CMCSs can be enhanced by tuning parameters, such as pH and concentration, and the incorporation of a rigid ligand affords excellent mechanical strength to the resultant assemblies. With CMCS jammed at the interface, liquids can be easily printed or molded to the desired shapes, with biocompatible walls that can be used to encapsulate and adsorb active materials. This study opens a new pathway to generate complex, all-liquid devices with a myriad of potential applications in biology, catalysis, and chemical separation.

Using host−guest molecular recognition at the oil−water interface, a new type of photoresponsive nanoparticle surfactant (NPS) was designed and prepared to structure liquids. With the help of a polymeric surfactant, the interfacial host−guest interactions can be significantly enhanced, leading to the rapid formation and assembly of a NP monolayer and offering sufficient binding energy to hold the NPs in a jammed state. The assembly of the NPSs can be reversibly manipulated via a photoswitchable jamming-to-unjamming transition, endowing the interface as well as the macroscopic assemblies with responsiveness to the external trigger (photons). This study for the first time opens a pathway for the construction of multiresponsive, structured all-liquid systems by introducing host−guest chemistry, showing promising potential applications in encapsulation, delivery systems, and unique microfluidic devices.

Using host−guest chemistries in a biphasic system, a novel supramolecular nanoparticle surfactant (s-NPS) with redox-responsiveness is presented to structure liquids. The in situ assembly/jamming and disassembly/unjamming of s-NPSs at the oil−water interface are reversibly controlled by a switchable redox process, imparting a nanoscale redox-responsiveness, affecting the assemblies on all length scales. "Smart" all-liquid constructs including structured emulsions and programmable liquid devices are easily prepared, showing promising applications in responsive delivery, release, and reaction systems.

The influence of physical confinement on the crystallization of poly­(ethylene oxide) (PEO) has received much attention in past years. Here, rather than constraining the crystallization of the polymer by a physical or geometric boundaries, the influence of the constraints imposed by the chain architecture on the crystallization of the PEO was investigated, where the PEO chains were anchored to a poly­(norbornene) (PNB) backbone. In this brush or comb-type polymer, the crystallizable polymer PEO are side chains comprising the bristles of the brush while the PNB comprises the spine. The brush or comb-type polymers were synthesized by the ring-opening metathesis polymerization (ROMP) of a NB-modified macromonomer. Here, the crystallizable PEO is anchored to the PNB backbone, placing constraints on the PEO during crystallization and annealing. The crystalline morphologies, crystallization kinetics, melting behavior, and crystal structure of the resultant polymers were investigated by polarized optical microscopy (POM), different scanning calorimetry (DSC), and X-ray scattering. Constraining the PEO to the PNB backbone was found to significantly influence the mobility of PEO chains, the degree of crystallinity, the crystal thickness and the equilibrium melting point. Increasing the molecular weight of the PEO or annealing at higher temperature alleviates this constraint to some extent. In addition to crystallization, the influence of annealing on the morphology was also investigated.