Abstract
Optical trapping enables the real-time manipulation and observation of morphological evolution of individual particles during reaction chemistry. Here, optical trapping was used in combination with Raman spectroscopy to conduct airborne assembly and kinetic experiments. Micro-droplets of alkoxysilane were levitated in air prior to undergoing either acid- or base-catalyzed sol–gel reaction chemistry to form silica particles. The evolution of the reaction was monitored in real-time; Raman and Mie spectroscopies confirmed the in situ formation of silica particles from alkoxysilane droplets as the product of successive hydrolysis and condensation reactions, with faster reaction kinetics in acid catalysis. Hydrolysis and condensation were accompanied by a reduction in droplet volume and silica formation. Two airborne particles undergoing solidification could be assembled into unique 3D structures such as dumb-bell shapes by manipulating a controlled collision. Our results provide a pipeline combining spectroscopy with optical microscopy and nanoscale FIB–SEM imaging to enable chemical and structural insights, with the opportunity to apply this methodology to probe structure formation during reactive inkjet printing.
Original language | English |
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Pages (from-to) | 11699–11706 |
Number of pages | 8 |
Journal | ACS Applied Nano Materials |
Volume | 5 |
Issue number | 8 |
Early online date | 17 Aug 2022 |
DOIs | |
Publication status | Published - 26 Aug 2022 |
Bibliographical note
Acknowledgments:This study was made possible thanks to funding from the Medical Research Council (grant number MR/N013913/1), the Engineering and Physical Sciences Research Council (grant number EP/M023877/1), and the Science and Technology Facilities Council─Central Laser Facility─for access to equipment funded under app. no.: 16130023. We would like to thank Royal Holloway, University of London, and STFC for funding Connor Barker’s PhD studies. We would like to thank Dr Ali Gholinia for his help with performing the FIB–SEM imaging and Professor Yasuaki Tokudome for his informative comments and suggestions on the discussion. Raw data requests to the authors for analysis are encouraged.