Characterization of Short Polypropylene Glycol Monoalkylethers and Design of Enzymatic Reaction Media
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Dissertation Characterization of short polypropylene glycol monoalkylethers and design of enzymatic reaction media Pierre Bauduin University of Regensburg At the Natural Sciences Faculty IV Chemistry & Pharmacy Mai 2005 Ph.D. Supervisor: Prof. Dr. Werner Kunz Adjudicators: Prof. Dr. Werner Kunz Prof. Dr. Barry W. Ninham Prof. Dr. Claudia Steinem Chair: Prof. Dr. Georg Schmeer Preface This thesis aims at the characterization of propyleneglycol monoalkylethers. It com- prises different studies ranging from phase diagram determination to enzymatic ac- tivity. For this reason this thesis was written so that each chapter can be read independently. Separate bibliographies are given at the end of each chapter. Each chapter layout follows the usual convention: Abstract, Introduction, Results and Discussion and Conclusion. The different studies led to publications which are already published, accepted or submitted, summarized in the following Table. Co- authors on the Ph.D. work in Regensburg are listed. A complete list of publications and a list of poster presentations, which were presented at international congresses, are also given at the end. i Preface Chapter Publication Bauduin, P.; Wattebled, L.; Schroedle, S.; Touraud, D.; Kunz, W. Tem- 2 perature dependence of industrial propylene glycol alkyl ether/water mix- tures. Journal of Molecular Liquids 2004 115(1), 23-28. Bauduin, P.; Wattebled, L.; Touraud, D.; Kunz, W. Hofmeister ion effects on the phase diagrams of water-propylene glycol propyl 3 ethers. Zeitschrift fuer Physikalische Chemie (Muenchen, Germany) 2004 218(6), 631-641. Bauduin, P.; Renoncourt, A.; Kopf, A.; Touraud, D.; Kunz, W. Uni- 4 fied concept of solubilization in water by hydrotropes and co-solvents. Langmuir (Submitted) 2005. Bauduin, P.; Basse, A.; Touraud, D.; Kunz, W. Effect of short non-ionic 5 amphiphiles derived from ethylene and propylene glycol alkyl ethers on the CMC of SDS. Colloids and Surfaces A (Accepted) 2004. Bauduin, P.; Touraud, D., Kunz, W. Design of low-toxic anionic temper- 6 ature sensitive microemulsions using short propyleneglycol alkylethers as co-surfactants. Langmuir (Submitted) 2005. Bauduin, P.; Nohmie, F.; Touraud, D.; Neueder, R.; Kunz, W.; Ninham, B.W. Hofmeister Specific-Ion Effects on Enzyme Activity and buffer pH: 7 Horseradish Peroxidase in citrate buffer. Journal of Molecular Liquids (Accepted) 2005. Bauduin, P.; Renoncourt, A.; Touraud, D.; Kunz, W.; Ninham, B. W. 7 Hofmeister effect on enzymatic catalysis and colloidal structures. Current Opinion in Colloid and Interface Science 2004 9(1,2), 43-47. Bauduin, P.; Touraud, D.; Kunz, W.; Ninham, B.W. The influence of 8 structure and composition of a reverse SDS microemulsion on enzymatic activities. Journal of Colloid Interface Science (Submitted) 2005. ii Acknowledgements The present work took place between October 2002 and May 2005 at the Department of Physical Chemistry for Natural Sciences at the University of Regensburg under the leadership of Prof. Dr. Werner Kunz. First and foremost, I would like to thank Prof. Dr. Werner Kunz not only for giving me the opportunity to do my Ph.D. in his lab but also for his unstinting support in countless ways both privately and professionnally. I would also like to thank Prof. Dr. Barry W. Ninham with whom I had the privilege to work during his stay in Regensburg. His kindness and his innovative way of seeing Science were of great help for me. Thanks to Prof. Dr. Jean-Marie Aubry for accepting me in his lab in May 2004, within the framework of an exchange between his laboratory in Lille and the laboratory of Regensburg, and for the always fruitful scientific discussions we had during this time and before that. I would like to thank all my research group-colleagues, for whom a single page of thanks would not suffice, for their kindness and technical support down these years. Special thanks to Didier Touraud for his constant support and his unique and unconventional way of approaching the Science. More personally, I would like to thank: Andreas G. who became a true friend dur- ing these last three years and tried to teach me the nice bavarian dialect (I´m afraid he did not succeed well but anyway...), Sigrid whose friendship and constant cheer- fulness contributed to my well-being in the lab 1, Alina, Astrid, Cristina, Andreas K., Chamsoudine, Nicolas and John for their friendship. Of course I would like to thank my family not only for putting me on earth, but also for coming to my assistance whenever I needed it. Without them I would never have become what I am today. Last but not least I want to particularly offer my heartfelt thanks to Audrey Renoncourt for her unvaluable support in the lab and in the every-day life. 1Sigrid: thank you so much for importing these delicious Dutch honey waffles in Bavaria and for bringing them into our lives! iii Acknowledgements iv Contents Preface i Acknowledgements iii Introduction 7 1 Overview of “glycol ethers” and of their industrial applications 9 1.1 Glycol ethers . 9 1.2 Health effects . 11 1.3 Structures and properties of propylene glycol alkyl ethers (CnPOm) . 14 1.3.1 Structures . 14 1.3.2 Synthesis and isomer compositions . 14 1.3.3 Physical properties and comparisons to other solvents . 15 1.4 Propylene glycol alkyl ethers (CnPOm): efficient and low toxic indus- trial solvents . 17 1.4.1 Deinking of cables . 17 1.4.2 Degreasing of metal plates . 21 Bibliography 29 I Properties and characterization of CnPOm/water mixtures 31 2 Temperature dependence of propylene glycol alkyl ether/water mixtures 33 2.1 Introduction . 33 2.2 Materials and Methods . 34 2.2.1 Materials . 34 2.2.2 Phase diagram determination . 35 2.2.3 Surface tension measurements . 36 2.3 Results and Discussion . 36 2.3.1 Phase diagrams . 36 2.3.2 C3PO1/water system . 38 2.3.3 n-propyl CnPOm / water phase diagrams . 39 2.3.4 C3POm/water phase diagrams . 40 2.3.5 C4POm/water phase diagrams . 40 1 Contents 2.3.6 Comparison of the LCST values between the CnEOms and the CnPOms.............................. 41 2.4 Conclusion . 42 Bibliography 43 3 Hofmeister effects on propylene glycol propyl ethers 47 3.1 Introduction . 47 3.2 Experimental . 50 3.2.1 Materials . 50 3.2.2 Cloud point determination . 50 3.3 Results . 51 3.4 Discussion . 54 3.5 Conclusion . 57 Bibliography 59 4 Unified concept of solubilization in water by hydrotropes and co-solvents 63 4.1 Introduction . 63 4.2 Experimental . 65 4.2.1 Materials . 65 4.2.2 Solubilization experiments . 66 4.3 Modelling . 66 4.4 Results and Discussion . 66 4.4.1 Solubilization curves: comparison between hydrotrope, co- solvent and surfactant . 66 4.4.2 Aqueous solubilization in the water rich part: the hydrotropic behavior . 69 4.4.3 The ordering of the hydrotropes . 71 4.4.4 The extent of the hydrophobic part in hydrotrope molecules: a determining factor in the hydrotropic efficiency . 72 4.5 Conclusion . 75 Bibliography 77 II Co-surfactant properties of CnPOms 81 5 Effect of propyleneglycol monoalkylether on the CMC of SDS 83 5.1 Introduction . 83 5.2 Materials and Methods . 84 5.3 Results and Discussion . 86 5.4 Conclusion . 93 Bibliography 95 2 Contents 6 Propyleneglycol monoalkylethers as co-surfactants in the design of mi- croemulsions 97 6.1 Introduction . 97 6.2 Experimental Section . 99 6.2.1 Materials . 99 6.2.2 Phase diagrams determination . 99 6.2.3 Phase transition determination by increasing temperature . 100 6.3 Results and Discussion . 101 6.3.1 CnPOm as co-surfactant in the formation of microemulsions . 101 6.3.2 Temperature dependence of CnPOm/SDS based systems . 103 6.3.3 Design of an anionic monophasic temperature sensitive mi- croemulsion using C4PO3 as co-surfactant . 108 6.4 Conclusion . 111 Bibliography 113 III Enzymatic activity 119 7 Hofmeister Specific-Ion Effects on Enzyme Activity and Buffer pH 121 7.1 Introduction . 121 7.2 Materials and Methods . 122 7.2.1 Materials . 122 7.2.2 Determination of the ABTS kinetic constants . 123 7.3 Results . 123 7.3.1 pH variation of a 0.025M citrate buffer with salt concentration 123 7.3.2 KmABT S and VmaxABT S as a function of pH . 125 7.3.3 KmABT S and VmaxABT S as a function of salt concentration . 125 7.4 Discussion . 126 7.4.1 Can we trust our pH values? . 126 7.4.2 The catalytic constants KmABT S and VmaxABT S . 128 7.4.3 The catalytic efficiency (VmaxABT S /KmABT S) . 128 7.5 Conclusion . 131 7.6 Appendix . 131 Bibliography 135 8 Enzymatic activity in reverse SDS microemulsions 137 8.1 Introduction . 137 8.2 Materials and Methods . 140 8.2.1 Materials . 140 8.2.2 Conductivity Experiments . 140 8.2.3 Preparation of the Reaction Mixtures . 140 8.2.4 Determination of Enzyme Activity . 140 3 Contents 8.3 Results . 142 8.3.1 Phase diagrams of microemulsions . 142 8.3.2 Conductivity Measurements . 142 8.3.3 Preliminary Enzymatic Tests . 146 8.3.4 Dependence of the enzymatic activity on the alcohol carbon number for various buffer contents . 147 8.4 Discussion . 148 8.4.1 Phase Diagrams . 148 8.4.2 Conductivity measurements . 150 8.4.3 Preliminary Enzymatic Tests . 151 8.4.4 Microemulsions: the dependence of the enzymatic activity on the number of carbon atoms in the alcohols at different water contents . 152 8.5 Conclusion . 157 Bibliography 161 Conclusion 171 List of Figures 173 List of Tables 179 List of Publications 181 List of Poster Presentations in Congress 183 4 Introduction 5 The toxicological and environment matters associated with the massive use of chlorinated solvents as well as ethers derivated from ethylene glycol in degreasing process and cleaning formulations involved a regulatory review.