Supramolecular polymer networks are non-covalently crosslinked soft materials that exhibit unique mechanical features such as self-healing, high toughness and stretchability. Previous studies have focused on optimising such properties using fast-dissociative crosslinks (i.e. for aqueous system, k d > 10 s -1 ). Herein, we describe non-covalent crosslinkers with slow, tuneable dissociation kinetics (k d < 1 s -1 ) that enable high compressibility to supramolecular polymer networks. The resultant glass-like supramolecular networks have compressive strengths up to 100 MPa with no fracture, even when compressed at 93% strain over 12 cycles of compression and relaxation. Notably, these networks show a fast, room-temperature self-recovery (< 120 s), which may be useful for the design of high-performance soft materials. Retarding the dissociation kinetics of non-covalent crosslinks through structural control enables access of such glass-like supramolecular materials, holding significant promise in applications including soft robotics, tissue engineering and wearable bioelectronics.Supramolecular polymer networks (SPNs) are a class of soft materials composed of linear polymers transiently crosslinked through non-covalent interactions. 1, 2 On account of the dynamic nature of these crosslinks, they can serve as sacrificial bonds to dissipate applied energy, thus imparting SPNs with remarkable material properties including high toughness, 3 enhanced damping capacity, 4 extreme stretchability, 5-7 rapid self-healing 8-10 , and reversible mouldability. 11 These superior material properties have lead to the use of SPNs as repairable electrodes, 12, 13 artificial skins, 14,15 and drug-delivery devices 16,17 . Although promising strides have been made, the material requirements for some demanding applications have not yet been met. A major limitation of SPNs is achieving extreme compressibility with ultra-high compressive strength and complete self-recovery on short time scales.Comparing covalently to non-covalently crosslinked polymers, the dissociation kinetics for dynamic networks plays a critical role in the material design and mechanical properties of the SPNs. 1 Craig and co-workers revealed that it is in fact crosslink dynamics, rather than equilibrium thermodynamics, that are paramount in determining the material properties (e.g. viscoelasticity) of SPNs. 18,19 They reported that slower dissociation kinetics resulted in more intact crosslinks within a transient network under an applied force, leading to a higher complex modulus. Holten-Anderson et al. further demonstrated control over hierarchical polymer mechanics through tuning the relative ratio of two kinetically-distinct metal-ligand crosslinks, which allowed for decoupling of the material mechanics from crosslink structure. 20 These pioneering reports established the basis for understanding the relationship between crosslink kinetics and SPN material properties.

1:2 Choline chloride:urea and 1:1 choline chloride:oxalic acid deep eutectic solvents (DES) are compared at 338 K using liquid-phase neutron diffraction with H/D isotopic substitution to obtain differential neutron scattering cross sections and fitting of models to the experimental data using Empirical Potential Structure Refinement (EPSR). In comparison to the previously reported study of choline chloride:urea at 303 K, we observed significant weakening and lengthening of choline-OH•••Cland choline-OH•••hydrogen-bond acceptor correlations.

Interactive materials are at the forefront of current materials research with few examples in the literature. Researchers are inspired by nature to develop materials that can modulate and adapt their behavior in accordance with their surroundings. Stimuli‐responsive systems have been developed over the past decades which, although often described as “smart,” lack the ability to act autonomously. Nevertheless, these systems attract attention on account of the resultant materials' ability to change their properties in a predicable manner. These materials find application in a plethora of areas including drug delivery, artificial muscles, etc. Stimuli‐responsive materials are serving as the precursors for next‐generation interactive materials. Interest in these systems has resulted in a library of well‐developed chemical motifs; however, there is a fundamental gap between stimuli‐responsive and interactive materials. In this perspective, current state‐of‐the‐art stimuli‐responsive materials are outlined with a specific emphasis on aqueous macroscopic interactive materials. Compartmentalization, critical for achieving interactivity, relies on hydrophobic, hydrophilic, supramolecular, and ionic interactions, which are commonly present in aqueous systems and enable complex self‐assembly processes. Relevant examples of aqueous interactive materials that do exist are given, and design principles to realize the next generation of materials with embedded autonomous function are suggested.

ARTICLEThis journal is © The Royal Society of Chemistry 2013 J. Name., 2013

Phenyl-perfluorophenyl polar−π interactions have been revisited for the design and fabrication of functional supramolecular systems. The relatively weak associative interactions (ΔG ≈ −1.0 kcal/mol) have limited their use in aqueous selfassembly to date. Herein, we propose a strategy to strengthen phenyl-perfluorophenyl polar−π interactions by encapsulation within a synthetic host, thus increasing the binding affinity to ΔG= −15.5 kcal/mol upon formation of heteroternary complexes through social self-sorting. These heteroternary complexes were used as dynamic, yet strong, cross-linkers in the fabrication of supramolecular gels, which exhibited excellent viscoelasticity, stretchability, self-recovery, self-healing, and energy dissipation. This work unveils a general approach to exploit host-enhanced polar−π interactions in the design of robust aqueous supramolecular systems.

The liquid structure of pyridine-acetic acid mixtures have been investigated using neutron scattering at various mole fractions of acetic acid, χHOAc = 0.33, 0.50, and 0.67 and compared to the structures of neat pyridine and acetic acid. Data has been modelled using empirical potential structure refinement (EPSR) with a 'free proton' reference model, which has no prejudicial weighting towards either the existence of molecular or ionised species. Analysis of the neutron scattering results shows the existence of hydrogen-bonded acetic acid chains with pyridine inclusions, rather than the formation of an ionic liquid by proton transfer.

Supramolecular chemistry utilizing the macrocyclic hosts cyclodextrins (CDs) and cucurbit[n]urils (CB[n]s) is traditionally performed in aqueous media; however, their solubility is typically poor, especially for the family of CB[n]s. Through derivatization of these macrocycles their solubility can be augmented to enable enhanced solubility in water and in some organic solvents. The increase in solubility of these derivatized macrocycles allows for their use in a wider range of chemical environments and giving rise to myriad potential applications. The dissolution of parent CDs (α-, β- and γ-) and CB[n]s (n=6-8) in deep eutectic solvents (DES) is reported, showing dramatic enhanced solubility of the larger species in both families, CB[7] and CB[8] as well as β- and γ-CD, respectively. Furthermore, the host-guest properties are maintained in this new solvation medium.

Nature controls the assembly of complex architectures through self-limiting processes, however few artificial strategies to mimic these processes have been reported to date. Here, we demonstrate a system comprised of two types of nanocrystals (NCs), where the self-limiting assembly of one NC component controls the aggregation of the other. Our strategy uses semiconducting InP/ZnS core-shell NCs (3 nm) as effective assembly-modulators and functional nanoparticle surfactants in cucurbit[n]uril-triggered aggregation of AuNCs (5-60 nm)