FREDDY BOSCÁN EMULSION POLYMERIZATION OF SUPERHYDROPHOBIC MONOMERS EMULSION POLYMERIZATION OF SUPERHYDROPHOBIC MONOMERS FREDDY BOSCÁN Chemical Engineering Group University of Basque Country (UPV/EHU) Donostia- San Sebastian (2017) (c)2017 FREDDY ENRIQUE BOSCAN GUERRA TABLE OF CONTENTS CHAPTER I. INTRODUCTION AND OBJECTIVES ............................. 1 1.1. Introduction ............................................................................... 3 1.2. Emulsion Polymerization .......................................................... 5 1.3. Water-borne Polymerization of Superhydrophobic Monomers 16 1.3.1. Miniemulsion Polymerization ............................................ 18 1.3.1.1. Miniemulsification by High-Shear Devices ................... 19 1.3.1.2 Miniemulsification by Phase Inversion ......................... 21 1.3.1.3 Polymerization of Phase-Inverted Miniemulsions ......... 28 1.3.2. Cyclodextrins as Transport Catalysts ............................... 34 1.3.3. Emulsifier Combination in Emulsion Polymerization ........ 37 1.3.4. Other Methods ................................................................. 41 1.3.5. Challenges at an Industrial Scale ..................................... 44 1.4. Objective ................................................................................ 49 1.5. Outline of the thesis ................................................................ 50 1.6. References ............................................................................. 51 CHAPTER II. EMULSIFIER COMBINATION IN EMULSION POLYMERIZATION .................................................................. 67 2.1. Introduction ............................................................................. 69 2.2. Experimental .......................................................................... 72 2.2.1. Materials........................................................................... 72 2.2.2. Synthesis of Polymer Dispersions .................................... 74 2.2.3. Characterization of Polymer Dispersions ......................... 78 2.3. LMA Homopolymerization ...................................................... 84 2.3.1. Batch Polymerizations...................................................... 85 2.3.2. Semi-batch Polymerizations ............................................. 88 2.4. LMA/BA/MMA Copolymerizations .......................................... 92 2.4.1. Film Properties ............................................................... 103 2.5. LMA/IBA Copolymerizations ................................................. 105 2.5.1. Effect of the Number of Particles ................................... 111 2.6. Polymerization Mechanism .................................................. 119 2.6.1. Micellar solubilization vs Droplet stabilization ................ 120 2.6.2. Monomer transport by collisions .................................... 125 2.6.3. Effect of the number of colliding species ........................ 130 2.7. Optimization of Emulsifier Content ....................................... 135 2.8. Conclusions .......................................................................... 143 2.9. References ........................................................................... 146 CHAPTER III. MINIEMULSIFICATION BY PHASE INVERSION TEMPERATURE .....................................................................149 3.1. Introduction .......................................................................... 151 3.2. Experimental ........................................................................ 156 3.2.1. Materials ........................................................................ 156 3.2.2. Miniemulsification by PIT ............................................... 157 3.2.3. Polymerization of the Miniemulsions .............................. 159 3.2.4. Characterization of Miniemulsions and Latexes ............. 160 3.3. Emulsifier Selection .............................................................. 162 3.4. Variables Affecting the PIT ................................................... 167 3.4.1. Effect of the Total Emulsifier Content on the PIT ........... 168 3.4.2. Effect of the Emulsifier HLB on the PIT .......................... 170 3.5. Stability of the Miniemulsions Prepared by PIT .................... 172 3.6. Polymerization of LMA Miniemulsions .................................. 178 3.7. Copolymerization of LMA/IBA by PIT ................................... 187 3.8. Conclusions .......................................................................... 189 3.9. References ........................................................................... 191 CHAPTER IV. PERFORMANCE OF WATER-BORNE COATINGS CONTAINING SUPERHYDROPHOBIC MONOMERS ....................... 197 4.1. Introduction ........................................................................... 199 4.2. Experimental – Polymer Latexes .......................................... 207 4.2.1. Materials......................................................................... 207 4.2.2. Synthesis of the LMA/IBA/PFA latex by EC ................... 208 4.2.3. Synthesis of the LMA/IBA/PFA latex by PIT ................... 209 4.2.4. Synthesis of the LMA/IBA/PFA latex by MP ................... 211 4.2.5. Synthesis of the BA/MMA/MAA latex by EP ................... 212 4.2.6. Characterization of the Polymer Films ........................... 213 4.3. Performance of the Latexes ................................................. 215 4.4. Experimental – Water-borne coatings .................................. 221 4.4.1. Materials......................................................................... 221 4.4.2. Synthesis of the LMA/IBA/MAA Latexes by EC .............. 222 4.4.3. Synthesis of the LMA/IBA Latexes by PIT ...................... 223 4.4.4. Formulation of the Water-borne Coatings ...................... 224 4.4.5. Evaluation of the Water-borne Coatings ........................ 226 4.5. Performance of the Water-borne Coatings ........................... 229 4.6. Conclusions .......................................................................... 239 4.7. References ........................................................................... 241 CHAPTER V. CONCLUSIONS .................................................. 245 ACKNOWLEDGMENTS ........................................................... 253 RESUMEN Y CONCLUSIONES ................................................. 260 Chapter I. INTRODUCTION AND OBJECTIVES 1.1. Introduction ............................................................................... 3 1.2. Emulsion Polymerization .......................................................... 5 1.3. Water-borne Polymerization of Superhydrophobic Monomers 16 1.3.1. Miniemulsion Polymerization ............................................ 18 1.3.1.1. Miniemulsification by High-Shear Devices ................... 19 1.3.1.2 Miniemulsification by Phase Inversion ......................... 21 1.3.1.3 Polymerization of Phase-Inverted Miniemulsions ......... 28 1.3.2. Cyclodextrins as Transport Catalysts ............................... 34 1.3.3. Emulsifier Combination in Emulsion Polymerization ........ 37 1.3.4. Other Methods ................................................................. 41 1.3.5. Challenges at an Industrial Scale ..................................... 44 1.4. Objective ................................................................................ 49 1.5. Outline of the thesis ................................................................ 50 1.6. References ............................................................................. 51 Chapter I 2 Introduction and Objectives 1.1. INTRODUCTION It is difficult to overstate how essential water is to most of the living organisms of this planet, and humankind is no exception. However, while water and life are generally associated, the relation between water and most human-made materials and structures is not synergistic from an industrial point of view, ultimately leading to elevated operation and maintenance costs.[1,2] Among the most notable victims are the construction and manufacturing industries, both of them producing materials ubiquitous to daily life in the 21st century. Taking this into account, it should come as no surprise that water resistance is one of the most important features of a protective coating, and finding ways to create coatings that can satisfy this and other performance properties expected from today’s materials has been a prevalent subject of academic and industrial research since a few decades.[3,4] Within this research, it is possible to identify two general ideas: i) the modification of the surface of an otherwise conventional coating in order to provide hierarchical roughness and severely decrease wetting;[5-13] and ii) the use of materials with enhanced hydrophobicity, mainly during the synthesis of the binder that will eventually make up the final coating.[3,11,14-19] Most contributions tend to follow the first approach when looking towards obtaining “superhydrophobic” surfaces; a term that has been coined for surfaces whose water contact angles are above 3 Chapter I 150º, and whose objective is to mimic structures found in nature such as the surfaces of lotus leaves or cicada wings.[20] However, it is inherently difficult to implement this technology in a widespread range of products manufactured in large quantities due to the prohibitively expensive post-application surface modification. The second approach,