Impact of nanoreactor anisotropy and confinement on chemical reactions

• Grant number: 24/04742-6
• Support Opportunities: Regular Research Grants
• Start date: November 01, 2024
• End date: October 31, 2028
• Field of knowledge: Physical Sciences and Mathematics - Chemistry - Physical-Chemistry
• Principal Investigator: Edvaldo Sabadini
• Grantee: Edvaldo Sabadini
• Principal researcher abroad: Viviane Lütz Bueno
• Institution abroad: Paul Scherrer Institute (PSI), Switzerland
• Host Institution: Instituto de Química (IQ). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

Efficient and fast chemical reactions are crucial for the production of expensive drugs, cosmetics, fragrances, and other high-end chemicals, hence the proper determination of the reaction yield is essential for cost control. Nanoreactors can host chemical reactions generating physical conditions at the nanoscale that allow difficult processes to take place with minimal energy expenditure, improving the efficiency. While microemulsions have been used as nanoreactors for decades, there has been a notable lack of research exploring how anisotropic confined nanoreactors can influence the rate, yield, and selectivity of chemical reactions compared to bulk and isotropic nanoconfinement conditions. This lack of exploration may be hindering our ability to find even more efficient reactions or new nanofabrication methods. Here, we propose a systematic empiric route to test such conditions. As nanoreactors, we select reverse wormlike micelles, which are ternary systems, composed of organic solvent, amphiphilic molecules and water. The ratio of water to amphiphilic molecules defines the micellar shape, length, and diameter, and consequently the dimensions of their water channels, where reactions can occur. These soft thermodynamic structures enable fine-control over confinement and anisotropy, being ideal model systems for this project. To quantify the impact of nanoreactor morphology on chemical reactions, we propose to monitor the product formation and yield of precipitation, redox and photo-polymerization reactions. The selection of rather simple model systems will enable us to focus on the mechanistic aspects of the reactions, and to provide a set of empiric guidelines for their control. We aim to compare these reactions in unconfined bulk conditions, within reverse spherical micelles under isotropic confinement, and within reverse wormlike micelles under anisotropic confinement. Furthermore, we will apply laminar flow fields to the anisotropic nanoreactors, and simultaneously probe alterations in reaction yield and product quality, which might happen due to the alignment of reverse wormlike micelles under flow. The key metrics of this project are the precise measurement of nanoreactor dimensions and reaction yield, as well as the characterization of the obtained products. We will quantify those parameters by in situ scattering and rheological experiments, while monitoring the micellization process and product formation in the nanoreactor in a well-controlled microfluidic chip. By combining the advantages of X-rays and neutrons as radiation sources, we will provide local, quantitative, and time-dependent information about the structural development of confined anisotropic nanoreactors, and characterize the reaction products within them, without external influences. This methodology does not require extracting the products from the nanoreactors, and simplifies their characterization and yield measurement, being an elegant strategy to answer our research question in a direct way. If proven feasible, anisotropic reactions under confinement could generate higher yield and be faster, improving large-scale industrial processes and having direct applications in nanotechnology, biophysics, catalysis, and nanofabrication of sensors and microelectronics. (AU)