Dr. Josep Puigmarti Luis

Senior Scientist

Josep

Journal

Sevim, S.; Sorrenti, A.; Franco, C.; Furukawa, S.; Pané, S.; deMello, A. J. Self-assembled materials and supramolecular chemistry within microfluidic environments: From common thermodynamic states to non-equilibrium structures. Chemical Society Reviews 2018, 47, 3788–3803

Self-assembly processes are crucial in the bottom-up fabrication of hierarchical supramolecular structures and advanced functional materials. Their control has traditionally relied on encoded building blocks bearing suitable moieties for recognition and interaction, while targeting the thermodynamic equilibrium state. On the other hand, nature founds the creation of hierarchical organized materials with surprisingly complex biological functions on the ultimate control of reaction diffusion processes. Indeed, under non-equilibrium conditions (kinetic control), the spatio-temporal command of chemical gradients and reactant mixing during self-assembly (e.g. creation of non-uniform chemical environments) can strongly affect the outcome of self-assembly process (i.e. the materials prepared), thus enabling an ultimate control over materials properties and functions. In this tutorial review, we will show how the unique microscale physical conditions offered by microfluidic technologies, in the first place mixing only based on reagent diffusion, can advantageously be used to control the self-assembly of materials, and of supramolecular aggregates in solution, making possible the isolation of intermediate states, unprecedented non-equilibrium structures, as well as the emergence of novel functions. In particular, the selected examples will confirm that microfluidic devices are a valuable toolbox technology to unveil, understand and steer self-assembly pathways to a desired structure and/or property/function, as well as advanced processing tools for device fabrication and integration.

Pérez del Pino, A.; González-Campo, A.; Giraldo, S.; Peral, J.; György, E.; Logofatu, C.; deMello, A. J.; Puigmartí-Luis, J. Synthesis of graphene-based photocatalysts for water splitting by laser-induced doping with ionic liquids. Carbon 2018, 130, 48–58

The synthesis of metal-free graphene-based photocatalysts has received great attention recently due to their expected contributions to the development of solar-based hydrogen generation via water-splitting in a low cost and ecological manner. In this work, a new method for the generation of nitrogen-doped graphene-based powder employing an alternative solution to commonly used toxic and hazardous organic solvents is presented. The procedure involves ultraviolet pulsed laser irradiation of graphene oxide (GO) flakes dispersed in 1-butyl-3-methylimidazolium [bmim]-based ionic liquids using both chloride and acetate anions. The structural and compositional analysis using transmission electron mi- croscopy, X-ray photoelectron and infrared spectroscopy indicate that the irradiated GO becomes partially reduced and doped with graphitic, pyrrolic and pyridinic nitrogen species. Interestingly, the relative content of the nitrogen functionalities is controlled by the anion in the ionic liquid and its concentration, with the obtained graphene-based powders showing higher photocatalytic activity than GO. Furthermore, a remarkable synergistic effect is observed for GO-[bmim]-acetate powder (acting as co-catalyst) in combination with anatase TiO2 nanoparticles. The presented method opens new research avenues for the cost-effective mass production of graphene-based photocatalysts for water splitting applications.

Abrishamkar, A.; Rodríguez-San-Miguel, D.; Rodríguez Navarro, J. A.; Rodriguez-Trujillo, R.; Amabilino, D. B.; Mas-Ballesté, R.; Zamora, F.; deMello, A. J.; Puigmarti-Luis, J. Microfluidic-based Synthesis of Covalent Organic Frameworks (COFs): A Tool for Continuous Production of COF Fibers and Direct Printing on a Surface. Journal of Visualized Experiments 2017

Covalent Organic Frameworks (COFs) are a class of porous covalent materials which are frequently synthesized as unprocessable crystalline powders. The first COF was reported in 2005 with much effort centered on the establishment of new synthetic routes for its preparation.To date, most available synthetic methods for COF synthesis are based on bulk mixing under solvothermal conditions. Therefore, there is increasing interest in developing systematic protocols for COF synthesis that provide for fine control over reaction conditions and improve COF processability on surfaces, which is essential for their use in practical applications. Herein, we present a novel microfluidic-based method for COF synthesis where the reaction between two constituent building blocks, 1,3,5-benzenetricarbaldehyde (BTCA) and 1,3,5-tris(4- aminophenyl)benzene (TAPB), takes place under controlled diffusion conditions and at room temperature. Using such an approach yields sponge-like, crystalline fibers of a COF material, hereafter called MF-COF. The mechanical properties of MF-COF and the dynamic nature of the approach allow the continuous production of MF-COF fibers and their direct printing onto surfaces. The general method opens new potential applications requiring advanced printing of 2D or 3D COF structures on flexible or rigid surfaces.

Rubio-Martinez, M.; Imaz, I.; Domingo, N.; Abrishamkar, A.; Mayor, T. S.; Rossi, R. M.; Carbonell, C.; deMello, A. J.; Amabilino, D. B.; Maspoch, D.; Puigmartí-Luis, J. Freezing the Nonclassical Crystal Growth of a Coordination Polymer Using Controlled Dynamic Gradients. Advanced Materials 2016, 28, 8150–8155

Manually engineered self-assembled structures have for many years been investigated under equilibrium conditions so that their most stable forms are reached, until recently. There has been a growing interest in obtaining and studying non-equilibrium self-assembled structures. The primary reason for this is that non-equilibrium structures (which are typically formed transiently under a constant influx of energy) can offer a broad number of intriguing opportunities in the development of novel materials and systems with advanced functionalities. For example, transient and/or steady-state self-assembled structures generated far from equilibrium are the basis of many sophisticated functions observed in living systems, e.g. DNA replication and/or cell division. Nonetheless, the controlled synthesis and study of intermediate, self-assembled structures is still a major challenge, which currently limits advancements in materials development and technology. Herein we show for first time a methodology that can be efficiently used to synthesize, isolate and study out-of-equilibrium crystal structures employing controlled and diffusion limited microfluidic environments. Unlike studies conducted with conventional mixing procedures in a flask, we prove experimentally and with numerical simulations that microfluidic technologies can undoubtedly fine-tune reaction times and reagents concentration profiles; factors that enable obtaining out of-equilibrium self-assembled crystal forms.

David Rodríguez-San-Miguel* & Afshin Abrishamkar*, Jorge A R Navarro, Romen Rodriguez-Trujillo, David B Amabilino, Ruben Mas-Balleste, Felix Zamora, Josep Puigmarti-Luis. Crystalline Fibres of a Covalent Organic Framework through bottom-up Microfluidic Synthesis. Chemical Communications, 2016, 52, 9212-9215. (*:equal contribution.)

A microfluidic chip has been used to prepare fibres of a porous polymer with high structural order, setting a precedent for the generation of a wide variety of materials using this reagent mixing approach that provides unique materials not accessible easily through bulk processes. The reaction between 1,3,5-tris(4-aminophenyl)benzene and 1,3,5-benzenetricarbaldehyde in acetic acid under continuous microfluidic flow conditions leads to the formation of a higly crystalline and porous covalent organic framework (hereafter named as MF-COF-1), consisting of fibrilar micro-structures, which have a mechanical stability that allows for a direct drawing of objects on a surface.

Abrishamkar, A.; Paradinas, M.; Bailo, E.; Rodriguez-Trujillo, R.; Pfattner, R.; Rossi, R. M.; Ocal, C.; deMello, A. J.; Amabilino, D. B.; Puigmartí-Luis, J. Microfluidic Pneumatic Cages: A novel approach for in-chip crystal trapping, manipulation and controlled chemical treatment. Journal of Visualized Experiments 2016

The precise localization and controlled chemical treatment of structures on a surface are significant challenges for common laboratory technologies. Herein, we introduce a microfluidic-based technology, employing a double-layer microfluidic device, which can trap and localize in situ and ex situ synthesized structures on microfluidic channel surfaces. Crucially, we show how such a device can be used to conduct controlled chemical reactions onto on-chip trapped structures and we demonstrate how the synthetic pathway of a crystalline molecular material and its positioning inside a microfluidic channel can be precisely modified with this technology. This approach provides new opportunities for the controlled assembly of structures on surface and for their subsequent treatment.