Louisiana Tech University Louisiana Tech Digital Commons Doctoral Dissertations Graduate School Spring 2016 Manufacturing polyacrylonitrile nanowires and nanofibers for sensing and energy storage applications Juan Chen Follow this and additional works at: https://digitalcommons.latech.edu/dissertations Part of the Chemical Engineering Commons, and the Nanoscience and Nanotechnology Commons MANUFACTURING POLYACRYLONITRILE NANOWIRES AND NANOFIBERS FOR SENSING AND ENERGY STORAGE APPLICATIONS by Juan Chen, B.S., M.S. A Dissertation Presented in Partial Fulfillment of the Requirements of the Degree Doctor of Philosophy COLLEGE OF ENGINEERING AND SCIENCE LOUISIANA TECH UNIVERSITY May 2016 ProQuest Number: 10300723 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. ProQuest 10300723 Published by ProQuest LLC(2017). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. Microform Edition © ProQuest LLC. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 LOUISIANA TECH UNIVERSITY THE GRADUATE SCHOOL FEBRUARY 18,2016 Date We hereby recommend that the thesis prepared under our supervision by Juan Chen, B.S., M.S. ______________________________ ______________________ entitled MANUFACTURING POLYACRYLONITRILE NANOWIRES _________ AND NANOFIBERS FOR SENSING AND ENERGY__________________________ STORAGE APPLICATIONS______________________ ________________________ be accepted in partial fulfillment of the requirements for the Degree of Doctor of Philosophy in Engineering _______ _________________________________ Supervisor of Thesis Research Headin'DepartmentHeadin'Department Engineering Department Recomniendationpbncurred in: Advisory Committee Approved: Approved: G raduate SchoolDirector of Graduate Studies Graduate SchoolDirector Dean of the College GSForm 13 (8/ 10) ABSTRACT A novel flow guided assembly approach is presented to well align and accurately position nanowire arrays in pre-defined locations with high throughput and large scale manufacturing capability. In this approach, polyacrylonitrile (PAN)/N, N- dimethylformamide (DMF) solution is first filled in an array of microfluidic channels. Then a gas flow is introduced to blow out most solutions while pushing a little leftover against the channel wall to assemble into polymer nanowires. In this way, highly-ordered nanowires are conveniently aligned in the flow direction and patterned along both sides of the microchannels. In this study, we demonstrated this flow-guided assembly process by producing millimeter-long nanowires across 5 mm * 12 mm area in the same orientation and with basic “I-shape”, “T-shape”, and “cross” patterns. The assembled polymer nanowires were further converted to conductive carbon nanowires through a standard carbonization process. After integrated into electronic sensors, high sensitivity was found in model protein sensing tests. This new nanowire manufacturing approach is anticipated to open new doors to the fabrication of nanowire-based sensing systems and serve as the Good Manufacturing Practices (GMP) (a system for ensuring that products are consistently produced and controlled according to quality standards) for its simplicity, low cost, alignment reliability, and high throughput. By using the same polymer solution (polyacrylonitrile (PAN)/N, N- dimethylformamide (DMF) solution), a new, simple, and low-cost method has been iv developed in the production of porous composite nanofibers via a one-step foaming and electrospinning process. Sublimable aluminum acetylacetonate (AAC A) was dissolved into polyacrylonitrile (PAN)/N, N-dimethylformamide (DMF) solution as the foaming agent. Silicon nanoparticles were then added and the resulting suspension solution was further electrospun to produce PAN/silicon composite nanofibers. The PAN nanofibers were then foamed during a thermal stabilization treatment and further carbonized into carbon/silicon composite nanofibers. Such mesoporous composites nanofiber mats were explored as the anode material for lithium ion batteries. Within this composite of nanofiber electrode, carbon nanofibers serve as the conductive media, while silicon nanoparticles ensure high lithium ion capacity and electrical density. The inter-fiber macrovoids and intra-fiber mesopores provide the buffering space to accommodate the huge volume expansion and consequent stress in the composite anode during the alloying process to mitigate electrode pulverization. Its high surface-to-volume ratio helps facilitate lithium ion transport between electrolytes and the active materials. Our electrochemical tests demonstrated higher reversible capacity and better capacity retention with this porous carbon/silicon composite nanofiber anode when compared with that made of nonporous composite nanofibers and CNF alone with similar treatments. APPROVAL FOR SCHOLARLY DISSEMINATION The author grants to the Prescott Memorial Library of Louisiana Tech University the right to reproduce, by appropriate methods, upon request, any or all portions of this Dissertation. It is understood that “proper request” consists of the agreement, on the part of the requesting party, that said reproduction is for his personal use and that subsequent reproduction will not occur without written approval of the author of this Dissertation. Further, any portions of the Dissertation used in books, papers, and other works must be appropriately referenced to this Dissertation. Finally, the author of this Dissertation reserves the right to publish freely, in the literature, at any time, any or all portions of this Dissertation. Author GS Form 14 (8/10) DEDICATION This dissertation is dedicated to my family who has supported me during the past seven years of living and study in US. vi TABLE OF CONTENTS ABSTRACT............................................................................. iii DEDICATION.............................................................................................................. vi LIST OF TABLES .................... x LIST OF FIGURES...................... xi ACKNOWLEDGMENTS..................................................... xiv CHAPTER 1 INTRODUCTION............... 1 1.1 Motivation ..................................................................................... 1 1.2 Objective... ........................................... 3 1.3 Outline ............................ 4 CHAPTER 2 LITERATURE REVIEW............................. 5 2.1 Current Status in Nanowire Sensor.... ............................................. 5 2.1.1 Nanowires Synthetic Method ....................... 7 2.1.2 Nanowire Alignment Method .......................................................... 7 2.1.2.1 Blown Bubble Film Method ....................... 8 2.1.2.2 Contact Printing Methods ........................ 9 2.1.2.3 Differential Roll Printing (DRP) ......... ...9 2.1.2.4 Micro Contact Printing ............................... 10 2.1.2.5 Langmuir-Blodgett (LB) Assembly ........ 12 2.1.3 Gas Blow/ Flow Guided Assembly ............................. 14 2.1.3.1 Alignment on Patterned Substrates ........ 16 2.1.3.2 Self Assembly of ID Nanostructures ........................................ ............18 vii 2.1.3.3 Solvent Evaporation Technique .............................. 20 2.2 Current Status of Electrospun Anode Material for Lithium Ion Batteries ........ 24 2.2.1 Principles of LIB ...........................................................................................26 2.2.2 New Anode Materials of LIB ....................................................................... 27 2.2.2.1 Carbon Based LIB Anode ......................................................................29 2.2.2.2 Si Nanowires Based Anode ...................................................................30 2.2.2.3 Si Nanoparticles Based Anode ..................................................... 32 2.2.2.4 Core-shell Si NWs ................................... 32 2.2.2.5 Hollow Si Nanostructures .......................................................33 2.2.2.6 Hollow Si Nanostructure with Clamping .............................................. 34 2 2 2 .1 Silicon/Carbon Nanofiber Composite Anode ........................................ 35 2.2.3 Electrospinning .................. 36 2.2.4 Other Methods for Improving LIB Properties ...................................... 37 2.2.5 Improve Electrochemical Performance by Adding Binder Materials ......... 38 CHAPTER 3 FLOW GUIDED ASSEMBLY CARBON NANOWIRE SENSOR 40 3.1 Introduction ................................. 40 3.2 Experiment Methods ......................... 42 3.2.1 Chemicals................................................................. 42 3.2.2 Polymer Solution Preparation ............ 42 3.2.3 Microfluidic Channel Template Fabrication of PAN Nanowire ..................42 3.2.4 Gas Blowing-based Flow-Guided Assembly Process ..................................44 3.2.5 Carbon Nanowire Production by Carbonation ........................... 45 3.2.6 Carbon Nanowire Sensor Testing ...................... ....45 3.3 Results and Discussion .............................................................................. 45 3.3.1 Characterizations of Nanowires.