ABSTRACT ZHANG, WENWEN. The Study of the Synthesis of a Water Soluble Antimicrobial Polymer. (Under the direction of Stephen Michielsen.) In this study we have tried to synthesize a water soluble antimicrobial polymer in order to produce an effective, reusable and skin friendly antimicrobial fabric while also lowering the production cost. The soluble polymer is a copolymer of acrylic acid, vinyl benzyl chloride, and 4-stryrene sulfonic acid. The antimicrobial agent, Rose Bengal, was expected to attach to the copolymer through a reaction with benzyl chloride, but it was found that this did not occur. Rather, a large amount of free dye was found at the completion of the reactions. To eliminate the free dye, the reaction conditions were adjusted. After testing several methods for quantitatively determining the amount of free dye in our samples, it was found that dialysis provided the best quantitation. The amount of free dye was measured at several points during the polymerization to understand the cause of residual free dye. We believe it is due to competition between –COOH groups on Rose Bengal and on acrylic acid. By modifying the polymerization conditions and the benzyl Rose Bengal monomer synthesis, water soluble and antimicrobial polymer was successfully polymerized with very little free dye remaining. This was accomplished by attaching Rose Bengal to vinyl benzyl chloride. Next this monomer was copolymerized with acrylic acid to enhance its water solubility. While the polymerization was occurring, the reaction mixture was added to an aqueous solution of 4-styrene sulfonic acid and the polymerization continued. © Copyright 2012 by Wenwen Zhang All Rights Reserved The Study of the Synthesis of a Water Soluble Antimicrobial Polymer by Wenwen Zhang A thesis submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Master of Science Textile Engineering Raleigh, North Carolina 2012 APPROVED BY: _______________________________ ______________________________ Dr. Stephen Michielsen Dr. David Hinks Committee Chair ________________________________ ________________________________ Dr. Melissa Pasquinelli Dr. Jan Genzer DEDICATION This thesis is dedicated to my parents and my advisor Dr. Stephen Michielsen ii BIOGRAPHY The author was born in Weifang, Shandong province, China in January 22th, 1989. She received the Shanghai Excellent Graduate award and received her Bachelor of Engineering in Textile Engineering (Textile Testing and Commerce) from Donghua University, China. In January, 2011, she joined the College of Textiles at North Carolina State University to pursue a Master of Science degree in Textile Engineering. She will continue onto her PhD degree in Fiber and Polymer Science in College of Textile, NC State. iii ACKNOWLEDGMENTS I appreciate Dr. Michielsen's help and encouragement throughout my research and life in the US. Without him, I would not be a master student in NC State. He guided me at every moment that I needed suggestions. He encouraged me to think and work by myself in order to get prepared for my PhD study. He offered me and my friends very nice help in my life when I needed his advice. He also taught me science knowledge and American English. I feel so lucky to be one of his students. I also acknowledge the members of my committee Dr. David Hinks, Dr. Melissa A. Pasquinelli, and Dr. Jan Genzer for their interest. I would like to thank Dr. Beck, Elton R. Lawrence and Brooke L. Kaznowski for their help during the study of vinyl benzyl Rose Bengal chemical structure. I would like to thank Jeff Kraus and Vicki Stocksdale for their help through my research. I would like to thank Jialong Shen and Joo Ram Kim for their help in conducting singlet oxygen production experiments and processing FTIR results, respectively. I would also like to thank College of Textiles’ staff, who helped me during my research. I wish to express my appreciation to Textile Engineering, Chemistry and Science department and LaamScience for funding this research. I thank my parents, brother and sister-in-law for their support throughout my life and during my study in the United States from overseas. I thank my friend Qian Jiang,Yuqiang Fu, Gabrielle Mineo and Elizabeth Phelps for their endless support throughout my study. iv TABLE OF CONTENTS LIST OF TABLES ................................................................................................................... ix LIST OF FIGURES ................................................................................................................. xi 1. INTRODUCTION ............................................................................................................. 1 2. LITERATURE REVIEW .................................................................................................. 3 2.1 Antimicrobial Fabric .................................................................................................. 3 2.1.1 Introduction ......................................................................................................... 3 2.1.2 Development ....................................................................................................... 3 2.2 Singlet oxygen ............................................................................................................ 4 2.2.1 Basic information ................................................................................................ 4 2.2.2 Biological Application ........................................................................................ 4 2.2.3 The production of singlet oxygen ....................................................................... 7 2.2.4 The test for singlet oxygen .................................................................................. 8 2.3 Rose Bengal.............................................................................................................. 10 2.3.1 Properties .......................................................................................................... 10 2.3.2 Test method- Beer-Lambert law ....................................................................... 11 2.4 Polymerization ......................................................................................................... 12 2.4.1 Introduction ....................................................................................................... 12 2.4.2 Redox Chain Copolymerization ........................................................................ 12 v 2.5 Surface Modification ................................................................................................ 13 2.5.1 Introduction ....................................................................................................... 13 2.5.2 Direct chemical treatment on fiber surface ....................................................... 14 2.5.3 Direct Polymerization on fiber surface ............................................................. 20 2.5.4 Chemical pretreatment plus polymerization ..................................................... 31 2.5.5 Plasma pretreatment plus polymerization ......................................................... 33 3. EXPERIMENTS .............................................................................................................. 36 3.1 Materials ................................................................................................................... 36 3.2 Polymerization Procedure ........................................................................................ 36 3.3 Synthesis of vinyl benzyl-Rose Bengal (VBRB) monomer ..................................... 37 3.4 Copolymerization ..................................................................................................... 37 3.4.1 Attaching Rose Bengal onto poly (acrylic acid-co-vinyl benzyl chloride-co- styrene sulfonic acid) ....................................................................................................... 38 3.4.2 Attaching Rose Bengal during copolymerization ............................................. 40 3.4.3 Polymerization of poly(acrylic acid-co-styrene sulfonic acid-co-vinyl benzyl chloride Rose Bengal) ..................................................................................................... 41 4. CHARACTERIZATION ................................................................................................. 44 4.1 Characterization of Final Product ........................................................................... 44 4.1.1 Free dye percentage evaluation ......................................................................... 44 vi 4.1.2 Solubility Test ................................................................................................... 49 4.1.3 Response to acidic and basic environment ....................................................... 49 4.1.4 Singlet Oxygen Production Rate Test ............................................................... 50 4.2 Characterization of Vinyl Benzyl Rose Bengal ....................................................... 52 4.2.1 High Performance Liquid chromatography (HPLC) ........................................ 52 4.2.2 Mass Spectrometry............................................................................................ 53 4.2.3 Fourier transform infrared spectroscopy (FTIR) .............................................. 54 4.2.4 Response to pH ................................................................................................