Coalescence and Particle Self-assembly of Inkjet-printed Colloidal Drops A Thesis Submitted to the Faculty of Drexel University by Xin Yang in partial fulfillment of the requirements for the degree of Doctor of Philosophy December 2014 ii © Copyright 2014 Xin Yang. All Rights Reserved. iii Acknowledgements I would like to thank my advisor Prof. Ying Sun. During the last 3 years, she supports and guides me throughout the course of my Ph.D. research with her profound knowledge and experience. Her dedication and passion for researches greatly encourages me in pursuing my career goals. I greatly appreciate her contribution to my growth during my Ph.D. training. I would like to thank my parents, my girlfriend, my colleagues (Brandon, Charles, Dani, Gang, Dong-Ook, Han, Min, Nate, and Viral) and friends (Abraham, Mahamudur, Kewei, Patrick, Xiang, and Yontae). I greatly appreciate Prof. Nicholas Cernansky, Prof. Bakhtier Farouk, Prof. Adam Fontecchio, Prof. Frank Ji, Prof. Alan Lau, Prof. Christopher Li, Prof. Mathew McCarthy, and Prof. Hongseok (Moses) Noh for their critical assessments and positive suggestions during my candidacy exam, proposal and my defense. I also appreciate the financial supports of National Science Foundation (Grant CAREER-0968927 and CMMI-1200385). iv TABLE OF CONTENTS LIST OF TABLES ............................................................................................................ vii LIST OF FIGURES ......................................................................................................... viii CHAPTER 1 : INTRODUCTION ...................................................................................... 1 1.1 Background ............................................................................................................... 1 1.2 Literature reviews ...................................................................................................... 2 1.2.1 Inkjet printing systems........................................................................................ 2 1.2.2 Drop formation ................................................................................................... 3 1.2.3 Drop impact and spreading ................................................................................. 6 1.2.4 Drop evaporation and particle deposition ........................................................... 8 1.3 Objectives ................................................................................................................ 14 CHAPTER 2 : EXPERIMENTAL MTHODS .................................................................. 16 2.1. Materials preparation.............................................................................................. 17 2.2. Process control ....................................................................................................... 19 2.3. In-situ observation .................................................................................................. 20 2.3.1. Drop formation ................................................................................................ 21 2.3.2. Drop impact, spreading, and evaporation ........................................................ 21 2.3.3. Particle self-assembly ...................................................................................... 22 CHAPTER 3 : OSCILLATION AND RECOIL OF SINGLE AND CONSECUTIVELY PRINTED DROPLETS .................................................................................................... 23 3.1 Introduction ............................................................................................................. 23 3.2 Experimental method .............................................................................................. 27 3.3 Results and discussion ............................................................................................. 29 3.3.1 Spreading and oscillation of a single drop........................................................ 29 3.3.2 Coalescence, recoil, and oscillation of two consecutively printed drops ......... 35 3.3.3 Comparison between drop impact on a dry surface and on a pre-deposited sessile drop ................................................................................................................ 39 3.4 Conclusion ............................................................................................................... 44 CHAPTER 4 : COALESCENCE, EVAPORATION AND PARTICLE DEPOSITION OF CONSECUTIVELY PRINTED COLLOIDAL DROPS .................................................. 46 v 4.1 Introduction ............................................................................................................. 46 4.2 Experimental methods ............................................................................................. 49 4.3 Results and discussion ............................................................................................. 50 4.3.1 Drop coalescence .............................................................................................. 50 4.3.2 Drop evaporation and deposition morphology ................................................. 56 4.4 Conclusions ............................................................................................................. 65 CHAPTER 5 : COMPETITION BETWEEN RECEDING CONTACT LINE AND PARTICLE DEPOSITION IN DRYING COLLOIDAL DROP...................................... 67 5.1 Introduction ............................................................................................................. 67 5.2 Experimental methods ............................................................................................. 69 5.3 Theoretical analysis ................................................................................................. 70 5.3.1 Contact line receding velocity of an evaporating drop ..................................... 70 5.3.2 Particle deposition rate at contact line .............................................................. 72 5.3.3 Ring spacing of the multi-ring structure ........................................................... 73 5.4 Results and discussion ............................................................................................. 75 5.4.1. Deposition morphology transition in droplets ................................................. 75 5.4.2 Interfacial instability near the drop contact line ............................................... 79 5.4.3 Effect of particle size ........................................................................................ 83 5.4.4 Deposition morphology map ............................................................................ 84 5.5 Conclusion ............................................................................................................... 86 CHAPTER 6 : SELF-ASSEMBLY OF NANOPARTICLES IN EVAPORATING PARTICLE LADEN-DEMULSION DROPS .................................................................. 88 6.1 Introduction ............................................................................................................. 88 6.2 Experimental method .............................................................................................. 89 6.3 Results and discussion ............................................................................................. 91 6.4 Conclusions ............................................................................................................. 97 CHAPTER 7 : SELF-ASSEMBLY OF NANOPARTICLES DIRECTED BY NANOPOROUS TEMPLATES ....................................................................................... 99 7.1 Introduction ............................................................................................................. 99 7.2 Experimental methods ........................................................................................... 101 7.3 Results and discussion ........................................................................................... 101 vi 7.3.1 Effect of annealing conditions on electrical properties and particle deposition morphologies ........................................................................................................... 101 7.3.2 Directed particle self-assembly into nanomesh .............................................. 103 7.3.3 Fabrication of Ag nanotubes with AAO membrane ....................................... 106 7.3.4 Fabrication of Ag nanotube forest on substrates ............................................ 108 7.4 Conclusion ............................................................................................................. 118 CHAPTER 8 : IMPACT OF DROPLETS ON LIQUID-INFUSED POROUS SURFACES .................................................................................................................... 119 8.1 Introduction ........................................................................................................... 119 8.2 Experimental methods ........................................................................................... 120 8.3 Results and discussion ........................................................................................... 122 8.4 Conclusion ............................................................................................................. 130 CHAPTER 9 : CONCLUSIONS AND RECOMMENDATIONS ................................. 132 9.1 Conclusions ..........................................................................................................