WWW.DISSERTATION.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Dissertations, online materials
 
<< HOME
CONTACTS



Pages:   || 2 | 3 | 4 | 5 |   ...   | 18 |

«RATIONAL DESIGN AND SYNTHESIS OF FUNCTIONAL POLYMERS WITH COMPLEX ARCHITECTURES BY LIVING/CONTROLLED POLYMERIZATION A Dissertation Presented to The ...»

-- [ Page 1 ] --

RATIONAL DESIGN AND SYNTHESIS OF FUNCTIONAL

POLYMERS WITH COMPLEX ARCHITECTURES BY

LIVING/CONTROLLED POLYMERIZATION

A Dissertation

Presented to

The Academic Faculty

by

Chaowei Feng

In Partial Fulfillment

of the Requirements for the Degree

Doctor of Philosophy in the

School of Materials Science and Engineering

Georgia Institute of Technology

May, 2015

COPYRIGHT© 2015 BY CHAOWEI FENG

RATIONAL DESIGN AND SYNTHESIS OF FUNCTIONAL

POLYMERS WITH COMPLEX ARCHITECTURES BY

LIVING/CONTROLLED POLYMERIZATION

Approved by:

Dr. Zhiqun Lin, Advisor Dr. John Reynolds School of Materials Science and School of Materials Science and Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Anselm C. Griffin Dr. Vladimir V Tsukruk School of Materials Science and Materials Science and Engineering Engineering Georgia Institute of Technology Georgia Institute of Technology Dr. Seth Marder School of Chemistry and Biochemistry Georgia Institute of Technology Date Approved: April 02, 2015 Dedicated to my loving family

ACKNOWLEDGEMENTS

I wish to thank my advisor Prof. Zhiqun Lin for his constant support, motivation, and generosity. His passion about science highly motivates me to conduct my research passionately through my Ph.D. He placed tremendous trust in me for generating ideas, solving problems, and accomplishing projects. I would also like to thank all my dissertation committees, Prof. Seth Marder, Prof. John Reynolds, Prof. Anselm Griffin, and Prof. Vladimir Tsukruk for their kind willingness to take part in my dissertation committee, and specially for providing me with valuable comments and feedbacks to guide me through my research and successfully achieve the thesis goal.

My PhD tenure has been a memorable one, only because of the congenial and supportive culture of the NanoFM research group. Particularly, I would like to thank Prof. Xinchang Pang and Dr. Lei Zhao for providing me with tremendous support and guidance on my research in the junior years. I would specially like to thank Yanjie He and Yijie Tao for being kind and supportive companions. I would also like to thank current and former NanoFM lab members, Prof. S. Li, Prof. Y. Yang, Prof. Y. Ren, Prof. H. Ma, Prof. R.

Wu, Prof. D. Yang, Prof. S. Wu, Dr. M. He, Dr. X. Xin, Dr. W. Han, Dr. M. Ye, Dr. Y.

Xu, Dr. S. Wannapop, C. Zhang, C. Wan, B. Li, J. Jung, C. Han, Y. Chen, X. Liu, B.

Jiang, J. Iocozzia, Young J.Yoon, A. Song, Z. Wang, J. Findley, D. Gottschalk, M.

Wang, H. Tang, H. Xu, D. Zheng, W. Liao, and N. Tipcompor for their constant help and support.

–  –  –

constant support, without whom I would not be here. Sincere gratitude goes to all my friends, Rui Ding, Liyi Li, Zhuo Li, Hongzhi Wang, Siyuan Zhang, Zhishuai Geng, Xin Dong, and Pan Zhang for their mental support over the years.

–  –  –

4 DESIGN AND SYNTHESIS OF SPHERICAL STAR BLOCK COPOLYMER

AS TEMPLATE TO DEVELOP UNIMOLECULAR CORE-SHELL AND

HOLLOW POLYMER NANOPARTICLES 55

–  –  –

5 ORGANO-SILICA HYBRID NANOPARTICLES AND NANOCAPSULES

FROM STAR POLYMERS WITH DIFFERENT ARCHITECTURES AS

UNIMOLECULAR NANOREACTORS 87

–  –  –

6.3.1. Synthesis of Cyclic Backbone Bearing Azide Functionalities 117 6.3.2. Synthesis of Conjugated Side Chains Capped with Ethynyl Group

–  –  –

Table 4.2: Structural parameters of polymer precursors and the prepared nanoparticles.

68 Table 5.1: Structural parameters of star-like PTMSPMA homopolymer and the corresponding organo-silica hybrid nanoparticles (NPs). 94

–  –  –

Table 5.3: Structural parameters of star-like PS-b-PTMSPMA diblock copolymers and the corresponding organo-silica hybrid nanocapsules (NCs).

104

–  –  –

Figure 1.2: Proposed mechanism for a photoredox-mediated ATRP proceeding through an oxidative quenching pathway with alkyl halides (top) and the use of perylene as an organic photocatalyst for the polymerization of methyl methacrylate with alkyl bromide initiators (bottom) and a photograph of this polymerization being mediated by natural sunlight (bottom right).

3

–  –  –

Figure 1.8: Schematic representation of the basic approach for the formation of SCK’s.

Micellization of amphiphilic 2 is followed by crosslinking through the styrenyl side chains located in the peripheral aqueous layer to yield 1. 16 Figure 1.9: Temperature-responsive micellization of block copolymers comprised of DMA, AAL, and NIPAM and the reversible IPEC micelle formation. 16 Figure 1.10: Schematic illustration of the environment-sensitive stabilization of the PIC micelle through the formation of a disulfide bond in the core. 17

–  –  –





Figure 1.12: Unstained TEM images of calcium phosphate mineralized polymer nanostructures: (a) shell cross-linked PAA-b-PI micelles; (b) cross-linked PAA nanocages.

In both cases, the inorganic shell is ca. 10 nm thick. 20

–  –  –

Figure 1.15: Schematic of the preparation of hybrid nanospheres by the self-assembly of reactive diblock copolymers.

The light gray corona represents the PEO, the dark gray core is the PTMSPMA, and the black core is the hybrid sphere for the polyorganosiloxane from the gelation process. 24

–  –  –

Figure 1.17: Strategy for the synthesis of an organic/inorganic hybrid nanocapsule.

26 Figure 3.1: Guidelines for selection of appropriate RAFT agent for various monomers.48 Figure 4.1: 1H-NMR spectra of star-like homopolymer. (a) star-like PCL, (b) polymeric RAFT agent star-like trithiocarbonate-end-functionalized PCL (i.e., PCL-TC).

Figure 4.2: GPC traces of (a) star-like PCL with different molecular weights as summarized in Table S1, (b) star-like PCL-b-P(S-Cl) with different molecular weights as summarized in Table 1, (c) star-like PCL-b-P(S-Cl) before and after purification (i.

e., sample-c as an example). 66 Figure 4.3: UV-vis spectra for star-like PCL (black curve) and trithiocarbonate-endfunctionalized star-like PCL (i.e., PCL-TC; red curve). 69

–  –  –

Figure 4.6: AFM height image of partially crosslinked core-shell nanoparticles after exposing to UV irradiation for 20 min.

The close-up is shown as an inset. 72 Figure 4.7: FTIR spectra of star-like diblock copolymer template and polymer nanoparticles. (a) star-like PCL-b-P(S-N3) template, (b) core-shell nanoparticles, and (c) hollow nanoparticles. 72

–  –  –

Figure 4.9: AFM height images of star-like PCL-b-P(S-N3) diblock copolymer template.

(a) Top view, and (b) the corresponding 3D profile. 75

–  –  –

Figure 4.11: (a) TEM image of intermediately stained core-shell nanoparticles, and (b) the core and overall size distributions of nanoparticles for TEM image in (a).

(c) TEM image of heavily stained core-shell nanoparticles, and (d) size distribution of nanoparticles for TEM image in (c). 77

–  –  –

Figure 4.13: TEM image of nanocapsules after a long-term storage (heavily stained sample), showing aggregations of nanocapsules.

79 Figure 4.14: Morphologies of hollow polymer nanoparticles. (a) and (c) AFM height images of hollow nanoparticles and core-shell nanoparticles (i.e., prior to degradation of PCL core; fully crosslinked), respectively. (b) Cross-sectional profiles of hollow and core-shell nanoparticles obtained from the corresponding AFM height images in (a) and (c), respectively (i.e., straight lines across nanoparticles in (a) and (c)). (d) TEM image of hollow nanoparticles after staining. (e) Schematic illustration of the transition from core-shell nanocapsule (left) to collapsed hollow nanoparticles (right) on substrate after degradation of PCL blocks. 81

Figure 4.15: Structure of Os-atom containing dye: osmapentalyne. 82

xii Figure 4.16: Encapsulation and release of dyes. (a) UV-Vis spectra of core-shell nanoparticles loaded with two different dyes (i.e., RhB with an absorption maximum of 559 nm (red dash curve) and osmapentalyne with an absorption maximum of 424 nm (black curve)). (b) TEM image of nanoparticles loaded with osmapentalyne. (c) Fluorescence spectra of partially crosslinked nanoparticles loaded with RhB in chloroform, and (d) florescence intensity at the emission of 572 nm as a function of time, showing different release rates of RhB from nanoparticles of different crosslinking density in THF and CHCl3 (i.e., partially crosslinked nanoparticles in CHCl3 (black squares), fully crosslinked nanoparticles in CHCl3 (red circles), and partially crosslinked nanoparticles in THF (blue triangles)). The curves are used for guidance. 84

–  –  –

Figure 5.4: TEM characterizations of organo-silica hybrid nanoparticles and nanocapsules.

(a) Hybrid nanoparticles crafted from sample-1 (i.e., star-like PTMSPMA) with smaller molecular weight; the average diameter of nanoparticle, Dave = 13 ± 2 nm. (b) Hybrid nanoparticles created from sample-2 (i.e., star-like PTMSPMA) with larger molecular weight; the average diameter of nanoparticle, Dave = 38 ± 4 nm. (c) Hybrid nanocapsules produced from sample-a (i.e. star-like PS-b-PTMSPMA) with larger molecular weight of the outer PTMSPMA block; the average diameter of nanocapsule, Dave = 71 ± 5 nm. (d) Hybrid nanocapsules yielded from sample-d, with smaller molecular weight of the outer PTMSPMA block; the average diameter of nanocapsule, Dave = 28 ± 5 nm. 99 Figure 5.5: Size distributions of hybrid nanoparticles and nanocapsules obtained from the TEM image analysis. The average diameters of nanoparticles or nanocapsules are summarized in Table 5.1 and Table 5.3, respectively. (a) Organo-silica hybrid nanoparticles crafted from sample-1 (i.e. star-like PTMSPMA with smaller molecular weight). (b) Organo-silica hybrid nanoparticles crafted from sample-2 (i.e. star-like PTMSPMA with larger molecular weight). (c) Organosilica hybrid nanocapsules created from sample-a (i.e. star-like PS-bPTMSPMA with larger molecular weight of outer PTMSPMA block). (d) Organo-silica hybrid nanocapsules created from sample-d (i.e. star-like PS-bPTMSPMA with smaller molecular weight of outer PTMSPMA block). 100

–  –  –

Significant progress has been made in the field of living/controlled polymerizations over the past decades. The advance in living/controlled polymerizations has enabled the design and tailoring of structurally well-defined macromolecules with complex architectures. Polymers with complex molecular architectures often exhibit properties that are distinct from their linear counterparts. This dissertation aims to exploit the unique properties of rationally designed complex polymer structures to address the challenges related to the preparation of polymeric and hybrid nanostructures, as well as to explore and fundamentally understand the morphology or properties of new macromolecular architecture.

The studies presented in this dissertation addressed the challenges (e.g., poor size uniformity, limited accessible compositions) in the formation of polymeric or hybrid nanostructured materials based on the self-assembled polymer micelle approach via rational design of complex spherical star polymer architectures with tailor-made compositions and functionalities through living/controlled polymerizations, as well as investigated the morphology and self-assembly behavior of a newly designed cyclic brush copolymer grafted with P3HT as the side chains. Specifically, the uniqueness of

this study can be summarized through the following novel and critical findings:

1. Uniform core-shell polymer nanoparticles can be formed by photo-crosslinking the shell layer of a monodisperse core-shell star block copolymer with azide moieties attached in the shell block. The dimensions of nanoparticles including the core size and the overall diameter are governed by the molecular weights of constituent blocks (i.e.

inner and shell block) in the core-shell star diblock copolymer template.

–  –  –

produced by etching the degradable inner core of the unimolecular shell-crosslinked nanoparticles.

3. Organo-silica hybrid nanostructures can be crafted if the sol-gel chemistry of trimethylsilyl groups attached to the star polymer templates is employed as the crosslinking mechanism. Nanoparticles were yielded when the trimethylsilyl groups were incorporated in the inner block of star polymers, while nanocapsules with an interior cavity were produced when trimethylsilyl moieties were integrated in the shell block.

4. The novel cyclic brush copolymer composed of PEG as the backbone and P3HT as the side chains self-assembled into an interesting and unique macro-ring morphology in selective solvent.

The novel and robust star macromolecular templating strategy developed in this study will open the access to a wide range of structurally and functionally well-defined polymeric and hybrid nanostructured materials with tailor-made compositions and shapes. The findings presented in the work will provide fundamental insights or practical strategies for rational design of polymers with complex macromolecular architectures via living/controlled polymerizations.

–  –  –



Pages:   || 2 | 3 | 4 | 5 |   ...   | 18 |


Similar works:

«Uncertainty, Reward, and Attention in the Bayesian Brain. Louise Whiteley Dissertation submitted for the degree of doctor of philosophy of the university of london Gatsby computational neuroscience unit university college london 1 Declaration I, Louise Emma Whiteley, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the thesis. 17th September 2008 2 Abstract The ‘Bayesian Coding...»

«Molecular Modeling of Polymer Free Volume Distribution A Dissertation Presented to The Academic Faculty by Derrick B. Callander In Partial Fulfillment Of the Requirements for the Degree Doctor of Philosophy in Chemical and Biomolecular Engineering Georgia Institute of Technology December 2005 Copyright © Derrick B. Callander 2005 Molecular Modeling of Polymer Free Volume Distribution Approved by: Dr. Peter J. Ludovice, Advisor Dr. William J. Koros School of Chemical and Biomolecular School of...»

«Murderous Visions of Relativity In the Novels Das Parfum and Oceano mare Mattia Marino by BEYOND MOURNING Social rites attempt to fill in the bodily gaps left by death. The aesthetic rituals of the novels Das Parfum (1985) by Patrick Süskind and Oceano mare (1993) by Alessandro Baricco come to terms with death in representations of murder which convey a relativist conception of being as presence, based on creative and critical dissent from the social resentment revolving around the dualist...»

«TRUTH, REPENTANCE AND NABOTH’S VINEYARD: TOWARDS RECONCILIATION IN AOTEAROA NEW ZEALAND ALISTAIR REESE BTh; BA (Hons); MA (Hons) WOLFSON COLLEGE UNIVERSITY OF CAMBRIDGE 2007 This dissertation is submitted for the degree of Master of Philosophy 1 Table of Contents 1. Introduction 1 2. The Gospel Imperative of Reconciliation 6 3. Missions and Māori 20 4. The Land and the Loss of ‘Naboth’s Vineyard’ 37 5. The Restoration of ‘Naboth’s Vineyard’? The Search for Reconciliation in...»

«DESIGN OF FAULT TOLERANT CONTROL SYSTEMS by Benjamin Erik Walker A dissertation submitted to the faculty of The University of North Carolina at Charlotte in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Electrical Engineering Charlotte 2012 Approved by: Dr. Bharat Joshi Dr. Yogendra Kakad Dr. James Conrad Dr. Mehdi Miri Dr. Edgar Munday ii ©2012 Benjamin Erik Walker ALL RIGHTS RESERVED iii ABSTRACT BENJAMIN ERIK WALKER. Design of fault tolerant control...»

«Behavioral Correlates of Hippocampal Neural Sequences Anoopum S. Gupta CMU-RI-TR-11-36 Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Robotics The Robotics Institute School of Computer Science Carnegie Mellon University Pittsburgh, Pennsylvania 15213 September 2011 Thesis Committee David S. Touretzky (Chair) Tai Sing Lee Reid Simmons George Stetten A. David Redish, University of Minnesota Copyright c 2011 by Anoopum S. Gupta. All rights reserved....»

«NEURONAL MECHANISM OF INCREASED MOTIVATION FOR OPERANT ETHANOL SELF-ADMINISTRATION CAUSED BY INTERMITTENT ETHANOL BINGE EXPOSURES By ZHIMIN LI A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2008 1 © 2008 Zhimin Li 2 To my parents: Shiqiao Li and Hongji Tian and my husband Yushi Qiu 3 ACKNOWLEDGMENTS First, I would like to express my sincere thanks to my mentor,...»

«AN ASIAN INDIAN DIETARY ACCULTURATION MEASURE: INSTRUMENT DEVELOPMENT AND VALIDATION By Sumathi Venkatesh A DISSERTATION Submitted to Michigan State University in partial fulfillment of the requirements for the degree of Human Nutrition – Doctor of Philosophy ABSTRACT AN ASIAN INDIAN DIETARY ACCULTURATION MEASURE: INSTRUMENT DEVELOPMENT AND VALIDATION By Sumathi Venkatesh Background: Asian Indian adults in the U.S. (~1% of the total population) have a high prevalence of type 2 diabetes...»

«TEXTUAL PROJECTIONS: THE EMERGENCE OF A POSTCOLONIAL AMERICAN GOTHIC By ROBERT C. SCHACHEL A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2006 Copyright 2006 by Robert C. Schachel To my father ACKNOWLEDGMENTS I thank my committee chair and mentor, Dr. David Leverenz, for all of his encouragement, support, insight, and academic guidance over the past eleven years....»

«COMBINED EXPERIMENTAL/THEORETICAL APPROACH TOWARD THE DEVELOPMENT OF CARBON TOLERANT ELECTROCATALYSTS FOR SOLID OXIDE FUEL CELL ANODES by Eranda Nikolla A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Chemical Engineering) in The University of Michigan Doctoral Committee: Assistant Professor Suljo Linic, Co-chair Professor Johannes W. Schwank, Co-chair Professor Erdogan Gulari Professor John W. Halloran Professor Phillip E. Savage ©...»

«CONDITION MONITORING OF ELECTROLYTIC CAPACITORS FOR POWER ELECTRONICS APPLICATIONS A Dissertation Presented to The Academic Faculty by Afroz M. Imam In Partial Fulfillment Of the Requirements for the Degree Doctor of Philosophy in the School of Electrical and Computer Engineering Georgia Institute of Technology May, 2007 CONDITION MONITORING OF ELECTROLYTIC CAPACITORS FOR POWER ELECTRONICS APPLICATIONS Approved by: Prof. Ronald G. Harley, Advisor Prof. Deepak M. Divan, Co-advisor School of...»

«Necessity in Kant; Subjective and Objective DAVID T. LARSON University of Kansas Kant suggests that his contribution to philosophy is analogous to the contribution of Copernicus to astronomy—each involves the revolutionary reorientation of a discipline. Kant describes his revolution as the move from taking objects to be determinative of knowledge to taking knowledge to be determinative of objects. This revolution should be seen in its proper context; it is Kant's response to such philosophers...»





 
<<  HOME   |    CONTACTS
2016 www.dissertation.xlibx.info - Dissertations, online materials

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.