Clemson University TigerPrints All Dissertations Dissertations 12-2007 Ultrahydrophobic Surface Modification of Polymeric Fibers and Inorganic Substrates Karthik Ramaratnam Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_dissertations Part of the Materials Science and Engineering Commons Recommended Citation Ramaratnam, Karthik, "Ultrahydrophobic Surface Modification of Polymeric Fibers and Inorganic Substrates" (2007). All Dissertations. 147. https://tigerprints.clemson.edu/all_dissertations/147 This Dissertation is brought to you for free and open access by the Dissertations at TigerPrints. It has been accepted for inclusion in All Dissertations by an authorized administrator of TigerPrints. For more information, please contact [email protected]. ULTRAHYDROPHOBIC SURFACE MODIFICATION OF POLYMERIC FIBERS AND INORGANIC SUBSTRATES A Dissertation Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Materials Science and Engineering by Karthik Ramaratnam December 2007 Accepted by: Dr. Igor A. Luzinov, Committee Chair Dr. Gary C. Lickfield Dr. Philip J. Brown Dr. Jian Luo Dr. Douglas E. Hirt ABSTRACT The wettability of a solid surface is a very important property, and is governed by both the chemical composition and the geometrical microstructure of the surface. Wettability and repellency are important properties of solid surfaces from both fundamental and practical aspects. The wettability of the solid surface is a characteristic property of materials and strongly depends on both the surface energy and the surface roughness. These properties may be approached by mimicking hydrophobic structures created by nature on lotus leaf surface. The lotus effect is based on surface roughness caused by different microstructures together with the hydrophobic properties of the epicuticular wax. The present study investigates the basic principles involved in the fabrication of lotus-like materials on both fibrous and inorganic substrates utilizing the two essential requirements, surface roughness and hydrophobicity. The surface roughness was created either by a porous or a bumpy profile while the hydrophobicity was achieved by grafting a non-fluorinated hydrophobic polymer. For the porous profiles, polymer blend systems showing phase separation were utilized whereas the bumpy profiles were achieved using nanoparticles such as calcium carbonate, silver, or silica particles. In the last part of the research, functionalization of silica nanoparticles was investigated and the development of a universal modification step to obtain the ultrahydrophobic property is reported. In this approach, the adsorption of the polymer and the nanoparticles to fibers has been optimized and the self-cleaning effect of these fabrics modified with silica nanoparticles has also been demonstrated. ii DEDICATION I would like to thank my parents and brothers for their constant support and encouragement till date. I would like to dedicate this work to my maternal grandparents, particularly my late grandfather who kept asking me about my graduation, for which I never had a straight-forward answer. iii ACKNOWLEDGEMENTS First and foremost, I would like to thank my advisor Dr. Igor Luzinov, for providing me this wonderful opportunity without which none of this would have been possible. He was an excellent supervisor, a great teacher and above all a very reasonable, humorous and a wonderful person. He never left me stranded during the course of my stay here and have always given me a helping hand when I needed his support the most. I sincerely express my gratitude to him, who can be nothing less than simply being the best. I would like to thank my committee members Dr. Philip J. Brown, Dr. Gary. C. Lickfield, Dr. Jian Luo and Dr. Douglas E. Hirt for their guidance, suggestions and encouragement. I would like to specially thank Dr. Lickfield for his assistance in reviewing this dissertation. I greatly appreciate all of my committee members for their time and effort spent in guiding me through my research work. I would also like to acknowledge Dr. Konstantin Kornev for his advice and guidance. As a member of Dr. Luzinov’s group, no one can by-pass Dr. Viktor Z. Klep, research professor in the group. I was able to ask him any question, scientific and non- scientific, and he always had a very good answer. I would like to specially thank him for all the guidance, help and suggestions provided. He is in many ways similar to Dr. Luzinov, and all the kind words mentioned above in the first paragraph apply to him as well. I would also like to thank my current and past group members for maintaining a great work atmosphere at the lab: Dr. Swaminatha Iyer, Dr. Bogdan Zdyrko, Dr. Yong Liu, Mrs. Olha Hoy and her husband Mr. Taras Andrukh, Mr. Suraj Sharma, Mr. iv Oleksandr Burtovyy, Dr. Volodymyr Tsyalkovsky, Dr. Ruslan Burtovyy and Mr. Zhenqing Li. This was a great group with very good people. I would like to thank Ms. Kimberly Ivey, Ms. Robbie Nicholson and Mr. James W. Lowe for their assistance during the course of my research work and the staff at the EM lab for their help with microscopy. I would also like to specially thank Ms. Barbara J. Ramirez, Director of the writing center and Class of 1941 studio for student communication, for her invaluable time and assistance in technical writing with some part of my dissertation. I also acknowledge Mr. Robert Teague for his help with LabView support. I am also grateful to all my friends, past and present roommates for the wonderful times spent together. I would also like to thank all the hard-working under-graduate and summer students, who worked with me in my research work: Jonathan Malphrus, Romain Epherre, Lex Nunnery, Jamie Hodges, David Longfield, Aussemon Ramezani, Wasim Kabir, and Ben Thompson. Last but not the least, I would like to thank the School of Materials Science and Engineering, Clemson University for this memorable experience. The education here will have a great impact going forward and I will cherish this moment forever. v TABLE OF CONTENTS Page TITLE PAGE....................................................................................................................i ABSTRACT.....................................................................................................................ii DEDICATION................................................................................................................iii ACKNOWLEDGEMENTS............................................................................................iv LIST OF FIGURES .......................................................................................................vii LIST OF TABLES........................................................................................................xiii CHAPTER 1: Introduction ..............................................................................................1 CHAPTER 2: Literature Review .....................................................................................7 CHAPTER 3: Experimental...........................................................................................46 CHAPTER 4: Wettability of Ultrathin Porous Hydrophobic Polymer Films Prepared from Phase Separated Polymer Blend Systems.......................60 CHAPTER 5: Two-step Approach using Calcium Carbonate Nanoparticles ...............96 CHAPTER 6: Surface Morphology of Cross-linked Triblock Copolymer Films .......122 CHAPTER 7: Multi-step Approach using Silver and Silica Nanoparticles ................147 CHAPTER 8: Functionalized Silica Nanoparticles Approach ....................................178 CHAPTER 9: Summary...............................................................................................220 CHAPTER 10: Appendix ............................................................................................228 vi LIST OF FIGURES Figure Page 2.1 Boundary between hydrophobicity and hydrophilicity represented IF using the plot of ∆Gsws , water contact angle as a function of the Lewis base parameter.........................................................................................10 2.2 Water structure and reactivity at biomaterials surfaces representing the BECB limit , that acts as a transition between the hydrophilic and hydrophobic surfaces .........................................................................................11 2.3 Schematic of a liquid placed on a solid with a definite contact angle ...............13 2.4 Wenzel contact angle mode ...............................................................................16 2.5 Cassie-Baxter contact angle mode.....................................................................16 2.6 Surface modification with polymers: physisorption, grafting to and grafting from approach ......................................................................................20 2.7 Chemical structures of polysiloxanes ................................................................26 2.8 SEM images of lotus leaf and its positive PDMS replica and a schematic illustration of the nano-casting of the leaf .........................................................29 2.9 Schematic representation of the heat and pressure driven nano-imprint pattern transfer process for nano-fabrication .....................................................30 2.10 FE-SEM and TEM images of BCH-LA films ...................................................32