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  • Morphology and Anisotropic Ionic Conductivity Properties of

    Poly(ethylene oxide)-Lithium Salt Holographic Polymer Dispersed

    Electrolyte Volume Gratings

    A Thesis

    Submitted to the Faculty

    of

    Drexel University

    by

    Derrick M Smith

    in partial fulfillment of the

    requirements for the degree

    of

    Master of Science in Materials Science and Engineering

    May 2011

  • Copyright 2011

    Derrick M Smith. All Rights Reserved

  • ii

    Dedication

    This work is dedicated to my family and friends, most specifically my fianc,

    Chelsea, and our friends at youth group. You guys have provided support, love

    and craziness to encourage me with everything through the broken laser days to

    the beautiful TEM micrograph imaging days.

  • iii

    Acknowledgements

    I would like to thank Dr. Christopher Li for his insightful comments and

    suggestions throughout this project, without whom this work would be much

    more scatterbrained.

    I would like to offer a special thanks to my committee members, Dr. Timothy

    Bunning and Dr. Yossef Elabd, for their time and helpful discussions.

    I would like to thank Yuesheng Ye from Dr. Elabds research group for his

    help running EIS with their 4-point probe electrode and helpful discussions on

    the results.

    I would like to thank the members of the Soft Matter Group, Dr. Michael

    Birnkrant, Russ Marron, Dr. Bin Dong, Eric Laird, Matthew Hood, Rebecca Chen,

    Shan Cheng, Wenda Wang, Tian Zhou and David Miller, with a special thanks to

    Dr. Bin Dong and Wenda Wang for hours of TEM imaging and Eric Laird for

    help with EIS.

    I also thank my fianc Chelsea for all her love and support.

  • iv

    Table of Contents

    Dedication ......................................................................................................................... ii

    Acknowledgements ........................................................................................................ iii

    List of Tables .................................................................................................................. viii

    List of Figures .................................................................................................................. ix

    Abstract ...................................................................................................................... xiv

    Chapter 1. Introduction ....................................................................................................1

    Chapter 2. Polymer Electrolytic Batteries ......................................................................5

    2.1 Lithium Based Systems.....................................................................................7

    2.2 Polymer Electrolyte Membranes .....................................................................9

    2.2.1 Obstacles in Polymer Battery Membranes ............................................11

    2.2.2 Current Technologies ...............................................................................12

    2.3 Materials Investigated for Polymer Batteries ..............................................13

    2.3.1 Ionic Conduction .......................................................................................14

    2.3.2 Copolymer Systems ..................................................................................18

    2.3.2.1 Glass Transition Dialing via Random Copolymers .........................18

    2.3.2.2 Volume Separation via Block Copolymers .......................................22

    2.3.3 Ceramic Fillers ...........................................................................................28

    2.3.4 Ionic liquids in Polymers Investigated ..................................................32

    2.5 Restrictions in Current Techniques ..............................................................39

    Chapter 3. Introduction to Hierarchical Nanostructures ..........................................40

  • v

    3.1 Photonic Crystals .............................................................................................42

    3.1.1 Theory .........................................................................................................44

    3.2 Nanofabrication Techniques ..........................................................................45

    3.3 Structure ...........................................................................................................48

    3.4 Holographic Lithography ..............................................................................49

    3.5 Holographic Polymer-Dispersed Photonic Crystals ..................................52

    3.6 Objectives of Dissertation ...............................................................................54

    Chapter 4. Methods and Materials ...............................................................................56

    4.1 Materials ...........................................................................................................56

    4.1.1 Photoinitiator and Monomers .................................................................56

    4.1.2 Homopolymer and Conducting Ions .....................................................57

    4.2 Method for Creating Volume Grating ..........................................................59

    4.3 Characterization ..............................................................................................62

    4.3.1 UV-Visible Transmission Spectroscopy .................................................63

    4.3.2 Electrochemical Impedance Spectroscopy ............................................64

    4.3.2.1 Bode, Phase and Nyquist plots ...........................................................64

    4.3.2.2 Point Probe ...........................................................................................69

    4.3.2.3 4 Point Probe .........................................................................................70

    4.3.3 Transmission Electron Microscopy ........................................................72

    4.3.4 Transmission Electron Microscopy Sample Preparation ....................73

    4.3.5 Optical Microscopy ...................................................................................74

    Chapter 5. Setup and Recipe Development ................................................................76

  • vi

    5.1 2-Point Electrode Setup ..................................................................................76

    5.1.1 4-Point Probe Validation ..........................................................................80

    5.1.2 Pure LiTFSI-PEO .......................................................................................82

    5.1.3 2-Point Probe Summary ...........................................................................83

    5.2 40% Weight LiTFSI ..........................................................................................84

    5.2.1 UV-Vis ........................................................................................................84

    5.2.2 Transmission Electron Microscopy ........................................................86

    5.2.3 Ionic Conductivity ....................................................................................88

    5.2.4 40% Weight LiTFSI Summary .................................................................97

    Chapter 6. 25% Weight LiTFSI in 400 Mw PEO .........................................................98

    6.1 Introduction .....................................................................................................98

    6.2 25% Weight LiTFSI UV-Vis ............................................................................98

    6.3 25% Weight Conductivity Data ...................................................................100

    6.3.1 Results .......................................................................................................101

    6.3.3 EIS Discussion .........................................................................................106

    6.3.3.1 Reflection Gratings .............................................................................106

    6.3.3.2 Transmission Gratings .......................................................................109

    6.3.4 Ionic Conductivity Plots .........................................................................110

    6.4 25% LiTSFI Summary ...................................................................................112

    Chapter 7. Structure and Morphology .......................................................................114

    7.1 Introduction ...................................................................................................114

    7.2 Transmission Electron Microscopy Micrographs .....................................114

  • vii

    7.3 Discussion .......................................................................................................117

    7.4 Structure Compared With Ionic Conductivity ..........................................122

    7.6 Summary ........................................................................................................126

    Chapter 8. Conclusions and Outlooks .......................................................................127

    8.1 Conclusions ............................................................

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