Andrew James Smith

Well‐defined diblock copolymer nanoparticles are prepared via reversible addition‐fragmentation chain transfer (RAFT) dispersion polymerization of 2‐hydroxyethyl methacrylate (HEMA) in a poly(α‐olefin) oil at 90°C using a poly(lauryl methacrylate) (PLMA) precursor. The PHEMA cores of these nanoparticles are subsequently swollen with up to 30% w/w aqueous 0.3 M HCl based on the PHEMA mass and then used as nanoreactors for the in situ synthesis of silica or titania using either tetraethyl orthosilicate (TEOS) or titanium tert ‐butoxide, respectively. The PLMA‐PHEMA nanoparticles are characterized by transmission electron microscopy, dynamic light scattering (DLS), and small‐angle x‐ray scattering (SAXS). The former technique indicates that core‐swelling leads to a subtle change in copolymer morphology from pseudo‐spherical to perfectly spherical nanoparticles. DLS and SAXS confirm the formation of near‐monodisperse nanoparticles of 92–117 nm diameter with colloidal stability being retained after the nanoreactor syntheses. For the silicified nanoparticles, time‐resolved turbidimetry and SAXS studies suggest a reaction timescale of around 50 min at 25°C. In this case, the final nanoparticle dispersion is highly transparent, whereas the corresponding titania‐loaded nanoparticles produce a highly turbid dispersion. Thermogravimetric analyses indicate silica and titania mass loadings of 17% and 21%, respectively. In both cases the inorganic phase is amorphous rather than crystalline.

Well‐defined diblock copolymer nanoparticles are prepared via reversible addition‐fragmentation chain transfer (RAFT) dispersion polymerization of 2‐hydroxyethyl methacrylate (HEMA) in a poly(α‐olefin) oil at 90°C using a poly(lauryl methacrylate) (PLMA) precursor. The PHEMA cores of these nanoparticles are subsequently swollen with up to 30% w/w aqueous 0.3 M HCl based on the PHEMA mass and then used as nanoreactors for the in situ synthesis of silica or titania using either tetraethyl orthosilicate (TEOS) or titanium tert ‐butoxide, respectively. The PLMA‐PHEMA nanoparticles are characterized by transmission electron microscopy, dynamic light scattering (DLS), and small‐angle x‐ray scattering (SAXS). The former technique indicates that core‐swelling leads to a subtle change in copolymer morphology from pseudo‐spherical to perfectly spherical nanoparticles. DLS and SAXS confirm the formation of near‐monodisperse nanoparticles of 92–117 nm diameter with colloidal stability being retained after the nanoreactor syntheses. For the silicified nanoparticles, time‐resolved turbidimetry and SAXS studies suggest a reaction timescale of around 50 min at 25°C. In this case, the final nanoparticle dispersion is highly transparent, whereas the corresponding titania‐loaded nanoparticles produce a highly turbid dispersion. Thermogravimetric analyses indicate silica and titania mass loadings of 17% and 21%, respectively. In both cases the inorganic phase is amorphous rather than crystalline.

LMWGs containing the tripeptide FFD motif show selective Li ⁺ responsiveness, forming entangled networks in the presence of Li ⁺ . This offers a simple supramolecular route to selective Li ⁺ uptake over competing monovalent cations.

Despite being the most abundant sustainable energy resource, solar energy still faces major challenges in efficient capture and long-term storage. Molecular Solar Thermal Energy Storage (MOST) systems address this issue by employing photoswitchable molecules that absorb sunlight and store energy through reversible isomerization, cyclization or other intramolecular rearrangements. Azobenzenes are attractive due to their well-characterized photoresponsive behavior; however, conventional systems are hindered by low energy density, limited energy storage duration, and a reliance on organic solvents. Here, we present the Micellar Solar Thermal Energy Storage system (MIST) approach based on micellar aggregates that operate effectively across aqueous dispersions and gel states. These systems exhibit progressively enhanced energy storage lifetimes with increasing degrees of self-assembly, while delivering competitive energy densities. The thermal stability arises from restricted molecular mobility within the self-assembled structures and is enhanced on gelation, extending the calculated thermal half-life of the cis isomer from 148 days in dimethyl sulfoxide (DMSO), to 233 days in water, and to 12.8 years in the gel state. Compared to previous azobenzene-based MOST systems, our MIST approach offers significantly extended energy storage durations and improved material processability, including water-compatible formulations and, macroscopic heat release in the gel state (up to 5.7 °C).

In situ TEM and synchrotron SAXS/WAXS show that FeCl₃ as a catalyst precursor results in considerably faster graphitization of cellulose than Fe(NO₃)₃.

Understanding the assembly of small molecules in aqueous media is crucial for the development of adaptive biomaterials. The mechanical properties of supramolecular networks, including stiffness and stress relaxation, play a key role in cellular spreading and can be tuned via formulation strategies or monomer design. Here, we demonstrate the modulation of supramolecular polymerization and cellular response of ureidopyrimidinone (UPy) monomers in water by tailoring the length of the alkyl spacer within the monomer structure. A library of four UPy derivatives with varying hydrophilic-hydrophobic balances was synthesized by using an optimized synthetic approach. The assembly behavior and dynamics of the supramolecular polymers were investigated both in solution and gel states using a wide range of techniques. The results revealed that the alkyl spacer length significantly affects the supramolecular polymer dynamics, kinetics, and stability. Monomers with 6 and 8 methylene units formed dynamic elongated structures, while those with 10 and 12 units yielded robust and stable bundled fibers. In the gel state, a physical cross-linker was required for gel formation. The gels formed by the monomers featuring 8 and 10 methylene units exhibited optimal mechanical properties, promoting the spreading of human normal dermal fibroblasts in both 2D and 3D cultures. These findings highlight the impact of the monomer architecture on the properties of UPy supramolecular systems, paving the way for the rational design of biomaterials with tunable properties.

Benzophenone-based materials remain widely used as photoinitiators for ultraviolet light-induced free radical polymerizations. Traditionally, polymerization is spatially controlled using top-down techniques such as photomasks, which produce well-defined polymeric films. In contrast, we present an alternative method for controlling polymerization by employing supramolecular materials to localize the photoinitiator. This approach uses benzophenone-functionalized dipeptides that are specifically tuned to enable supramolecular gel noodle formation, which act as structural templates. We show that polymerization of acrylate monomers around the gel noodles can increase the Young's modulus by up to 2 orders of magnitude and produce mechanically robust structures that can be handled. The self-assembly of the supramolecular photoinitiators is also explored using viscosity and SAXS measurements, providing an understanding of why only 4BPAcFF successfully forms gel noodles. Our method offers a simple yet effective technique for localizing polymerization, enabling fine-tuning of mechanical properties and the fabrication of intricate designs such as hollow-core structures.

Atmospheric aerosol hygroscopicity and reactivity play key roles in determining the aerosol’s fate and are strongly affected by its composition and physical properties. Fatty acids are surfactants commonly found in organic aerosol emissions. They form a wide range of different nanostructures dependent on water content and mixture composition. We follow nano-structural changes in mixtures frequently found in urban organic aerosol emissions, i.e. linoleic acid (LOA), oleic acid (OA), sodium oleate and fructose, during humidity change and exposure to the atmospheric oxidant ozone. Small-Angle X-ray Scattering (SAXS) was employed (Milsom et al., 2024) to derive the hygroscopicity of each nanostructure by measuring time- and humidity-resolved changes in nano-structural parameters. We found that hygroscopicity is directly linked to the specific nanostructure. Reaction with ozone revealed a clear nanostructure-reactivity trend, with notable differences between the individual nanostructures investigated. Simultaneous Raman microscopy complementing the SAXS studies revealed the persistence of oleic acid even after extensive oxidation. Our findings demonstrate that self-assembly of fatty acid nanostructures can significantly impact water uptake and chemical reactivity, thus directly affecting the atmospheric lifetime of these materials.Another focus of our studies are one-molecule thin layers of LOA and their behaviours when exposed to ozone in multi-component films at the air–water interface (Woden et al., 2024). LOA’s two double bonds allow for ozone-initiated autoxidation, a radical self-oxidation process, as well as traditional ozonolysis. Neutron reflectometry was employed to follow the kinetics of these films in real time in a temperature-controlled environment. We oxidised deuterated LOA (d-LOA) as a monolayer, and in mixed two-component films with either oleic acid (h-OA) or its methyl ester, methyl oleate (h-MO), at room temperature and atmospherically more realistic temperatures of 3 ± 1 °C. We found that the temperature change did not notably affect the reaction rate which was similar to that of pure OA. Kinetic multi-layer modelling using our Multilayer-Py package showed that neither temperature change nor introduction of co-deposited film components alongside d-LOA consistently affected oxidation rates, but the deviation from a single process decay behaviour (indicative of autoxidation) at 98 ppb is clearest for pure d-LOA, weaker for h-MO mixtures and weakest for h-OA mixtures. As atmospheric surfactants will be present in complex, multi-component mixtures, it is important to understand the reasons for these different behaviours even in two-component mixtures of closely related species. Our work demonstrates that it is essential to employ atmospherically realistic ozone levels as well as multi-component mixtures to understand LOA behaviour at low O3 in the atmosphere. Residue formation may be affected by the temperature change, potentially impacting on the persistence of the organic character at the surface of aqueous droplets. Our findings could have impacts on both urban air quality (e.g. protecting harmful urban emissions from atmospheric degradation and therefore enabling their long-range transport), and climate (e.g. affecting cloud formation), with implications for human health and wellbeing.Milsom et al., Atmos. Chem. Phys., 2024, 24, 13571–13586, DOI: 10.5194/acp-24-13571-2024, 2024.Woden et al., Faraday Discuss., 2024, DOI: 10.1039/D4FD00167B.

Benzophenone-based materials remain widely used as photoinitiators for ultraviolet light-induced free radical polymerizations. Traditionally, polymerization is spatially controlled using top-down techniques such as photomasks, which produce well-defined polymeric films. In contrast, we present an alternative method for controlling polymerization by employing supramolecular materials to localize the photoinitiator. This approach uses benzophenone-functionalized dipeptides that are specifically tuned to enable supramolecular gel noodle formation, which act as structural templates. We show that polymerization of acrylate monomers around the noodles can increase the Young’s modulus by up to two orders of magnitude and produce mechanically robust structures that can be handled. The self-assembly of the supramolecular photoinitiators is also explored using viscosity and SAXS measurements, providing an understanding of why only 4BPAcFF successfully form gel noodles. Our method offers a simple yet effective technique for localizing polymerisation, enabling fine-tuning of mechanical properties and the fabrication of intricate designs such as hollow-core structures.