Enhancing the scalability of crystallization-driven self-assembly using flow reactors

Anisotropic materials have garnered significant attention due to their potential applications in cargo delivery, surface modification, and composite reinforcement. Crystallization-driven self-assembly (CDSA) is a practical way to access anisotropic structures, such as 2D platelets. Living CDSA, where platelets are formed by using seed particles, allows the platelet size to be well controlled. Nonetheless, the current method of platelet preparation is restricted to low concentrations and small scales, resulting in inefficient production, which hampers its potential for commercial applications. To address this limitation, continuous flow reactors were employed to improve the production efficiency. Flow platforms ensure consistent product quality by maintaining the same parameters throughout the process, circumventing batch-to-batch variations and discrepancies observed during scale-up. In this study, we present the first demonstration of living CDSA performed within flow reactors. A continuous flow system was established, and the epitaxial growth of platelets was initially conducted to study the influence of flow parameters such as temperature, residence time, and flow rate on the morphology of platelets. Comparison of different epitaxial growth manners of seeds and platelets was made when using seeds to perform living CDSA. Size-controllable platelets from seeds can be obtained from a series flow system by easily tuning flow rates. Additionally, uniform platelets were continuously collected, exhibiting improved size and dispersity compared to those obtained in batch reactions

Seeing is believing: in-situ visualising dynamic evolution in CO2 electrolysis

CO2 reduction reaction (CO2RR), as a promising carbon-neutral strategy, enables the production of valuable chemicals and fuels from greenhouse gas. Despite tremendous efforts in developing CO2RR catalysts to improve activity, selectivity, and stability, mechanisms behind the catalytic performance, however, are still under-explored due largely to limited characterisation capability. In this review, advances of in-situ imaging technologies for studying CO2RR have been overviewed. These technologies emerge as powerful tools to track the transformation of catalyst materials over real-time and space, under CO2RR operating conditions. The review discusses emerging opportunities in the direction of combined in-situ characterisation techniques as well as machine learning to aid further discovery of structure-function relationships in CO2RR

2D Hierarchical Microbarcodes with Expanded Storage Capacity for Optical Multiplex and Information Encryption

The design of nanosegregated fluorescent tags/barcodes by geometrical patterning with precise dimensions and hierarchies could integrate multilevel optical information within one carrier and enhance microsized barcoding techniques for ultrahigh-density optical data storage and encryption. However, precise control of the spatial distribution in micro/nanosized matrices intrinsically limits the accessible barcoding applications in terms of material design and construction. Here, crystallization forces are leveraged to enable a rapid, programmable molecular packing and rapid epitaxial growth of fluorescent units in 2D via crystallization-driven self-assembly. The fluorescence encoding density, scalability, information storage capacity, and decoding techniques of the robust 2D polymeric barcoding platform are explored systematically. These results provide both a theoretical and an experimental foundation for expanding the fluorescence storage capacity, which is a longstanding challenge in state-of-the-art microbarcoding techniques and establish a generalized and adaptable coding platform for high-throughput analysis and optical multiplexing

Precise design and surface modification of poly(ε-caprolactone)-based 2D assemblies

This thesis investigates the precise design of poly(ε-caprolactone)-based 2D assemblies and their selective surface modification. Chapter One provides a broad introduction of the research, discussing the importance of achieving morphology and size control over nanostructures, polymerisation techniques, self-assembly methods, and surface modification approaches. Chapter Two demonstrates a controlled fabrication approach of uniform poly(ɛ-caprolactone)-based 2D assemblies utilizing seeded epitaxial crystallisation methods. Exquisite control over the multiblock co-micelles in morphology and dimensions was achieved by altering the amount of added unimers. Moreover, fluorescent labelling was achieved by polymer modification with fluorophores, providing a platform for future applications such as fluorescent imaging or biocompatible and biodegradable carriers. Chapter Three reports a facile method for the preparation of poly(ε-caprolactone)-based platelets via crystallisation-driven self-assembly (CDSA), in which the height can be finely tuned by in situ photo-RAFT polymerisation. Furthermore, a fluorescent monomer could be synthesised and polymerised on the surface of such platelets allowing confocal microscopic imaging. More importantly, the prepared 2D platelet micelles could be selectively functionalised on the surface with different monomers through selective photo RAFT polymerisation, achieving spatial control over the platelet height. Such strategy has opened the possibility of highly controlled surface functionalisation for soft materials, providing potential applications in material science and polymer chemistry. Chapter Four summarises the research presented in Chapter Two and Three, providing key conclusions as well as discussing the scope for future directions in this area of research

In situ characterisation for nanoscale structure-performance studies in electrocatalysis

Recently, electrocatalytic reactions involving oxygen, nitrogen, water, and carbon dioxide have been developed to substitute conventional chemical processes, with the aim of producing clean energy, fuels and chemicals. A deepened understanding of catalyst structures, active sites and reaction mechanisms plays a critical role in improving the performance of these reactions. To this end, in situ/operando characterisations can be used to visualise the dynamic evolution of nanoscale materials and reaction intermediates under electrolysis conditions, thus enhancing our understanding of heterogeneous electrocatalytic reactions. In this review, we summarise the state-of-the-art in situ characterisation techniques used in electrocatalysis. We categorise them into three sections based on different working principles: microscopy, spectroscopy, and other characterisation techniques. The capacities and limits of the in situ characterisation techniques are discussed in each section to highlight the present-day horizons and guide further advances in the field, primarily aiming at the users of these techniques. Finally, we look at challenges and possible strategies for further development of in situ techniques.</p

Real-time label-free imaging of living crystallization-driven self-assembly

The living crystallization-driven self-assembly (CDSA) of semicrystalline block copolymers is a powerful method for the bottom-up construction of uniform polymer microstructures with complex hierarchies. Improving our ability to engineer such complex particles demands a better understanding of precisely how to control the self-assembly process. Here, we apply interferometric scattering microscopy (iSCAT) to deliver real-time observation of individual poly(caprolactone)-based platelet growth. This label-free method enables us to map the role of key reaction parameters on platelet growth rate, size, and morphology. Furthermore, iSCAT provides a contrast mechanism for studying multi-layer platelets, offering new insights into the distribution of polymer compositions within a single platelet