DOCSLIB.ORG

Inorganic Polyhedral Oligomeric Silsesquioxanes (Poss) Based Polymers Gunjan A, Gadodia University of Massachusetts Amherst, [email protected]

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Inorganic Polyhedral Oligomeric Silsesquioxanes (Poss) Based Polymers Gunjan A, Gadodia University of Massachusetts Amherst, Gunjangadodia@3Aassociate.Com University of Massachusetts Amherst ScholarWorks@UMass Amherst Open Access Dissertations 9-2009 Synthesis and Study of Hybrid Organic – Inorganic Polyhedral Oligomeric Silsesquioxanes (poss) Based Polymers Gunjan A, Gadodia University of Massachusetts Amherst, [email protected] Follow this and additional works at: https://scholarworks.umass.edu/open_access_dissertations Part of the Polymer Science Commons Recommended Citation Gadodia, Gunjan A,, "Synthesis and Study of Hybrid Organic – Inorganic Polyhedral Oligomeric Silsesquioxanes (poss) Based Polymers" (2009). Open Access Dissertations. 97. https://doi.org/10.7275/x6zc-t890 https://scholarworks.umass.edu/open_access_dissertations/97 This Open Access Dissertation is brought to you for free and open access by ScholarWorks@UMass Amherst. It has been accepted for inclusion in Open Access Dissertations by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact [email protected]. SYNTHESIS AND STUDY OF HYBRID ORGANIC – INORGANIC POLYHEDRAL OLIGOMERIC SILSESQUIOXANES (POSS) BASED POLYMERS A Dissertation Presented By GUNJAN A. GADODIA Submitted to the Graduate School of the University of Massachusetts Amherst in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY September 2009 Department of Polymer Science and Engineering © Copyright by Gunjan A. Gadodia 2009 All Rights Reserved SYNTHESIS AND STUDY OF HYBRID ORGANIC – INORGANIC POLYHEDRAL OLIGOMERIC SILSESQUIOXANES (POSS) BASED POLYMERS A Dissertation Presented By GUNJAN A. GADODIA Approved as to style and content by: ____________________________________ E. Bryan Coughlin, Chair ____________________________________ Alfred J. Crosby, Member ____________________________________ Anthony D. Dinsmore, Member ________________________________ Shaw Ling Hsu, Department Head Polymer Science and Engineering DEDICATION To my beloved family ACKNOWLEDGEMENTS I would like to express my sincerest gratitude to my advisor and mentor Prof E. Bryan Coughlin. The journey towards my PhD would not have been possible without this constant support and encouragement. I would also like to thank him for his patience and freedom he gave me to try new and different things. Working with him, I have become a more optimist person, and a better communicator. I would also like to thank Prof. Al Crosby and Prof Anthony Dinsmore for serving on my committee. I have learned a great deal through their insightful comments and constructive criticism. I would like to acknowledge a number of collaborators with whom I have worked Prof. Sam Gido, Eric Anderson, Wim De Jeu, Ling Yang, Jiayu Wang and Prof. Tom Russell. I have learnt a lot working with them. I would especially like to thank Prof. Sam Gido, even though he was not on my committee he has always been available for discussions. Further, I would like to thank all the faculty members of Polymer Science and Engineering Department. I would also like to thank Dr. Stephen Eyles, Dr. Greg Dabkowski, Dr. Weiguo Hu, Dr. Sekar Dhanasekaran and Jack Hirsh for keeping the facilities up and running, and helping me to run my experiments. I also need to thank the administrative staff especially Erin and Vivien for their fantastic job. I would like to thank the sixth floor students, and the many other students with whom I have worked or interacted. It’s truly a great experience working in the Polymer Science and Engineering department at University of Massachusetts Amherst. It has been wonderful working in the Coughlin group and I would like to thank all present and past Coughlin group members. Push helped me in my first year to settle in v the group. I have learnt a lot from Nui and Brad, my fellow hybrid group members. It has been fun working around Ranga, Rich, Chris, Liz, Katie, Tsung Han, Bon-Choel, Makoto and Tarik. I have found friends for life in Ying, Shilpi, Gregoire, Yoan and Sergio. Ying has been fantastic friend for last the past 5 years, we started together and she has been very helpful to me. Hopefully in the future we will stay in touch with each other. Shilpi has also been a great friend for more than just research, we have discussed India, politics, life etc. Gregoire has been a great friend and a mentor. When I started, I had no synthetic skills and knowledge, he really helped me get started. We have been good friend since then and hopefully we will stay in touch. I think I have spent most time of my graduate life working around Yoan and Sergio. It has been a great cultural experience working with them. I am sure I will miss all of them once I go back to India. There is a huge Indian Mafia at UMASS and they make a foreign country, 10,000 miles away from India, feel like home. My roommates and friends, present and past, Nilanjan, Gautam, Abhishek, Srikant, Neha, Swetha, Raja, Mayur, Suresh and many others have been like a family. Deepak and Ajay have been special friends and I have enjoyed conversations with them and learnt a lot from them. Keyur and Vishal my high school friends have been great support in US. My friends Shreenath, Gopal and Pushkar in India have also been very supportive. Finally I would like to dedicate this thesis to my parents, sister Neha and girlfriend Janavi. It was only because of them that I have managed to do a Ph.D. Without their incessant love, support and patience this journey would not have been possible. It has been very difficult living away from them for 5 years and I look forward to my life with them. Thank you all! vi ABSTRACT SYNTHESIS AND STUDY OF HYBRID ORGANIC-INORGANIC POLYHEDRAL OLIGOMERIC SILSESQUIOXANE (POSS) BASED POLYMERS SEPTEMBER 2009 GUNJAN A. GADODIA, B.TECH., UNIVERISTY OF MUMBAI, INDIA M.S., UNIVERISTY OF MASSACHUSETTS, AMHERST Ph.D., UNIVERISTY OF MASSACHUSETTS, AMHERST Directed by: Professor E. Bryan Coughlin Hybrid organic-inorganic materials represent a new class of materials having scientific and technological potential. In this thesis, Polyhedral Oligomeric Silsesquioxanes (POSS) are used as an inorganic building block which has been tethered to an organic polymer. POSS are silica precusors, having a well defined silsesquioxane cental core surrounded by an organic periphery which makes them compatible with monomers and possibly polymers. The objectives of this study are to (1) study the basic structures of POSS homopolymers, (2) to incorporate POSS building blocks by a bottom- up approach into polymer chains and study the resulting morphologies, and (3) to study the thin film behavior of POSS block copolymers. PMA and styryl POSS homopolymers of different peripheries were synthesized by ATRP and mass spectrometry studies were carried out by MALDI-TOF and ESI. PMA POSS chains undergo a number of fragmentations while styrly POSS chains have a vii relatively robust backbone. Poly(ethylene-butylene-b-MAPOSS), AB type copolymers and poly(MAPOSS-b-styrene-b-MAPOSS), ABA type copolymers were synthesized by a combination of anionic and ATRP polymerization. Spheres, inverse cylinders, lamellar and crystalline lamellar morphologies were observed for the poly(ethylene-butylene-b- MAPOSS) copolymers. In the poly(MAPOSS-b-styrene-b-MAPOSS) copolymers, cylindrical, lamellar and perforated lamellar morphologies were obtained. Beyond the interaction parameter (χ), total degree of polymerization (N) and volume fraction (f), the conformational asymmetry (ε) also plays an important role in determining the morphology of these block copolymer. Crystallization of the POSS phase and better thermal properties were observed in the both block copolymers. Thin film studies of poly(MAPOSS-b-styrene-b-MAPOSS) copolymers showed that the microdomains can be oriented either parallel or perpendicular to the substrate depending upon the film thickness, morphology and relative volume fractions of the connecting blocks. By removal of the organic phase, ordered mesoporous low dielectric constant silica films were obtained. These hybrid block copolymers are a potential candidate for nanopatterning applications. viii TABLE OF CONTENTS ACKNOWLEDGEMENTS.................................................................................................v ABSTRACT...................................................................................................................... vii LIST OF TABLES............................................................................................................ xii LIST OF FIGURES ......................................................................................................... xiv LIST OF SCHEMES..........................................................................................................xx LIST OF ABBREVIATIONS AND SYMBOLS ............................................................ xxi CHAPTER 1. INTRODUCTION ...................................................................................................1 1.1 Hybrid Organic – Inorganic Materials...............................................................1 1.2 Self – Assembly of Block Copolymers..............................................................5 1.3 Hybrid Organic - Inorganic Polymers Based on Polyhedral Oligomeric Silsesquioxanes (POSS).....................................................................................7 1.3.1 Synthesis and Properties of Polyhedral Oligomeric Silsesquioxanes (POSS)...............................................................................7 1.3.2 POSS as Fillers .................................................................................12
Load more

Recommended publications
  • Main-Chain Phosphorus-Containing Polymers for Therapeutic Applications
    molecules Review Main-Chain Phosphorus-Containing Polymers for Therapeutic Applications Paul Strasser and Ian Teasdale * Institute of Polymer Chemistry, Johannes Kepler University Linz (JKU), Altenberger Straße 69, A-4040 Linz, Austria; [email protected] * Correspondence: [email protected] Received: 13 March 2020; Accepted: 4 April 2020; Published: 8 April 2020 Abstract: Polymers in which phosphorus is an integral part of the main chain, including polyphosphazenes and polyphosphoesters, have been widely investigated in recent years for their potential in a number of therapeutic applications. Phosphorus, as the central feature of these polymers, endears the chemical functionalization, and in some cases (bio)degradability, to facilitate their use in such therapeutic formulations. Recent advances in the synthetic polymer chemistry have allowed for controlled synthesis methods in order to prepare the complex macromolecular structures required, alongside the control and reproducibility desired for such medical applications. While the main polymer families described herein, polyphosphazenes and polyphosphoesters and their analogues, as well as phosphorus-based dendrimers, have hitherto predominantly been investigated in isolation from one another, this review aims to highlight and bring together some of this research. In doing so, the focus is placed on the essential, and often mutual, design features and structure–property relationships that allow the preparation of such functional materials. The first part of the review details the relevant features of phosphorus-containing polymers in respect to their use in therapeutic applications, while the second part highlights some recent and innovative applications, offering insights into the most state-of-the-art research on phosphorus-based polymers in a therapeutic context.
    [Show full text]
  • Dielectric Properties of Poly(Enaminonitrile)S
    Polymer Journal, Vol. 32, No. 1, pp 57-61 (2000) Dielectric Properties of Poly(enaminonitrile)s Ji-Heung K1M,t Sang You! KIM,* James A. MOORE,** and James F. MASON*** Department ()f Chemical Engineering, Sungkyunkwan University, 300 Chunchun, Jangan, Suwon, Kyonggi 440-746, Korea * Department of Chemistry, Korea Advanced Institute of Science and Technology, 373-1 Kusung, Yusung, Taejon 305-701, Korea ** Department of Chemistry, Polymer Science and Engineering Program, Rensselaer Polytechnic Institute, Troy, NY 12180-3590, U.S.A. *** ATOCHEM N.A. King of Prussia, PA 19406--0018, U.S.A. (Received June 9, 1999) ABSTRACT: Poly(enaminonitrile)s (PEANs), a new class of thermally stable aromatic polymers, possess excellent thermal stability, good mechanical properties and are easily soluble in many organic solvents. Flexible, tough films can be cast from these solutions. These polymers undergo a 'curing' reaction at 300--350°C to insoluble, more dimensionally stable materials without evolution of volatile byproducts. We summarize here the dielectric data measured at a frequency of 100 kHz, 25°C for some PEANs, and discuss the results in relation to their structures. KEY WORDS Poly(enaminonitrile) / Dielectric Constant / Thermally Stable Polymer / Structure- Property / The production of thermally stable organic polymers reflects the alignment of dipoles and the net polariza­ has been the subject of many research efforts for the past tion of the molecules which is attributed to restricted 30 years because of the growing application of thermally movement of charges within the material. In an electric stable polymers in the fields of aerospace and elec­ field, positive charges move with the electric field and tronics.1 ·2 Most of thermally stable polymers synthesiz­ an equal number of negative charges move against it ed are aromatic, rigid-rod type polymers that have resulting in no net charge anywhere in the sample.
    [Show full text]
  • Impact of the Pendant Group on the Chain Conformation and Bulk Properties of Norbornene Imide-Based Polymers † § ‡ § † ‡ Bret M
    Article Cite This: Macromolecules XXXX, XXX, XXX−XXX pubs.acs.org/Macromolecules Impact of the Pendant Group on the Chain Conformation and Bulk Properties of Norbornene Imide-Based Polymers † § ‡ § † ‡ Bret M. Boyle, , Ozge Heinz, , Garret M. Miyake,*, and Yifu Ding*, † Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, United States ‡ Department of Mechanical Engineering, University of Colorado, Boulder, Colorado 80309, United States *S Supporting Information ABSTRACT: Three series of well-defined norbornene imide-based polymers with different pendant groups were synthesized to investigate the effect of the pendant group on the polymer conformation in solution and bulk melt properties. Each of these three series was examined by analyzing the polymers’ bulk z-average 8 (UTC). radius of gyration via static light scattering and the polymers’ melt viscoelastic properties via oscillatory measurements and differential scanning calorimetry. Sterically bulky pendant wedge groups modestly increase the rodlike conformation of the norbornene- imide polymer, however, the inherent rigidity of the polymer main- chain can still be observed with less bulky substituents. In stark contrast, the different side groups significantly impacted the bulk o legitimately share published articles. viscoelastic and thermal properties. By increasing the pendant group size, the chain diameter of the polymer increases and lowers the entanglement modulus. Finally, as the wedge pendant group size increases, the segmental relaxation time and the fragility index of these norbornene-based polymers are decreased. ■ INTRODUCTION groups extending away from the backbone that contain one or Bottlebrush polymers are molecules containing densely spaced more branch points in which another generation of branches begins. Often, these dendronized polymers can be directly polymeric side chains grafted onto a central backbone.
    [Show full text]
  • Advances in Polycarbodiimide Chemistry
    Polymer 52 (2011) 1693e1710 Contents lists available at ScienceDirect Polymer journal homepage: www.elsevier.com/locate/polymer Feature Article Advances in polycarbodiimide chemistry Justin G. Kennemur, Bruce M. Novak* Department of Chemistry, North Carolina State University, USA article info abstract Article history: Over the last 15 years, large strides have been taken with regards to synthesis, catalysis, structural Received 21 December 2010 control, and functional application of polycarbodiimides (polyguanidines); a unique class of helical Received in revised form macromolecules that are derived from the polymerization of carbodiimide monomers using transition 13 February 2011 metal catalysis. This manuscript will provide a summary of the synthesis and characterization studies in Accepted 18 February 2011 addition to the large variety of properties discovered for these systems and potential applications Available online 3 March 2011 associated with these properties. In large part, it is the chiral helical backbone coupled with synthetically selective pendant groups which has allowed creation of polycarbodiimides spanning a large range of Keywords: Helical polymer potential applications. Such applications include cooperative chiral materials, liquid crystalline materials, Chiral polymer optical sensors and display materials, tunable polarizers, sites for asymmetric catalysis, and recyclable Polycarbodiimide polymers. Manipulation of the two pendant groups that span away from the amidine backbone repeat Polyguanidine unit has allowed solubility of these polymers in solvents ranging from cyclohexane to water, maximizing Asymmetric Catalysis the potential application of these polymers in various media. Liquid Crystals Ó 2011 Elsevier Ltd. All rights reserved. Chiro-optical Materials 1. Introduction further specificity will require their full description as non-linear or helical polycarbodiimides.
    [Show full text]
  • Caged Polyphosphazenes with a Visible‐
    COMMUNICATION Photocleavable Polymers www.mrc-journal.de Coumarin-Caged Polyphosphazenes with a Visible-Light Driven On-Demand Degradation Aitziber Iturmendi, Sabrina Theis, Dominik Maderegger, Uwe Monkowius, and Ian Teasdale* desired response. Consequently, several Polymers that, upon photochemical activation with visible light, undergo photo-responsive polymers have been pre- rapid degradation to small molecules are described. Through functionaliza- pared that have great promise in diverse tion of a polyphosphazene backbone with pendant coumarin groups sensitive applications such as drug delivery, porous membranes, and film patterning.[4b,9] to light, polymers which are stable in the dark could be prepared. Upon irra- Macromole cules that undergo photo- diation, cleavage of the coumarin moieties exposes carboxylic acid moieties chemical backbone degradation are also along the polymer backbone. The subsequent macromolecular photoacid is of significant interest.[10] Most reported found to catalyze the rapid hydrolytic degradation of the polyphosphazene photo-cleavable systems require ultraviolet backbone. Water-soluble and non-water-soluble polymers are reported, which (UV) light to achieve cleavage, which can due to their sensitivity toward light in the visible region could be significant be a drawback especially in biomedical environments due to low penetration and as photocleavable materials in biological applications. biocompatibility, hence a shift to longer wavelengths is required.[11] Coumarin and its analogs are widely employed
    [Show full text]
  • Polymer Science and Technology
    POLYMER SCIENCE AND TECHNOLOGY Robert O. Ebewele Department of Chemical Engineering University of Benin Benin City, Nigeria CRC Press Boca Raton New York Copyright 2000 by CRC Press LLC 8939-frame-discl Page 1 Monday, April 3, 2006 2:40 PM Library of Congress Cataloging-in-Publication Data Ebewele, Robert Oboigbaotor. Polymer science and technology / Robert O. Ebewele. p. cm. Includes bibliographical references (p. - ) and index. ISBN 0-8493-8939-9 (alk. paper) 1. Polymerization. 2. Polymers. I. Title. TP156.P6E24 1996 668.9--dc20 95-32995 CIP This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage or retrieval system, without prior permission in writing from the publisher. The consent of CRC Press LLC does not extend to copying for general distribution, for promotion, for creating new works, or for resale. Specific permission must be obtained in writing from CRC Press LLC for such copying. Direct all inquiries to CRC Press LLC, 2000 N.W. Corporate Blvd., Boca Raton, Florida 33431. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation, without intent to infringe.
    [Show full text]
  • Design, Synthesis and Characterization of Conjugated Polymers for Photovoltaics and Electrochromics
    THESIS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Design, Synthesis and Characterization of Conjugated Polymers for Photovoltaics and Electrochromics KIM BINI Department of Chemistry and Chemical Engineering CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2018 Design, Synthesis and Characterization of Conjugated Polymers for Photovoltaics and Electrochromics Kim Bini ISBN 978-91-7597-834-5 © Kim Bini, 2018. Doktorsavhandlingar vid Chalmers tekniska högskola Ny serie nr 4515 ISSN 0346-718X Division of Applied Chemistry Department of Chemistry and Chemical Engineering Chalmers University of Technology SE-412 96 Gothenburg Sweden Telephone + 46 (0)31-772 1000 Cover: An series of photos of the electrochromic transition of the polymer PIDTT from red/pink and absorbing to faint blue transmissive, along with schematic polymer structure and arbitrary CIE 1931 color coordinate system transition. Chalmers Reproservice Gothenburg, Sweden 2018 Design, Synthesis and Characterization of Conjugated Polymers for Photovoltaics and Electrochromics Kim Bini Department of Chemistry and Chemical Engineering Chalmers University of Technology Abstract With the invention of organic electronics, a new class of materials needed to be explored and suitable applications found. The use as semiconductors in many different devices has been explored, where photovoltaics, light-emitting diodes and field-effect transistors have been prominent. For most applications the organic semiconductors have some advantages when compared to their inorganic counterpart, such as molecular design variability, solution processing and flexible mechanical properties. These advantages are quickly making organic semiconductors an interesting alternative in a wide variety of fields. Organic photovoltaics (OPV) have developed rapidly the last decade and is currently close to being commercially viable for niche applications.
    [Show full text]
  • Polymer Chemistry
    Polymer Chemistry Mohammad Jafarzadeh Faculty of Chemistry, Razi University Polymer Science and Technology By Robert O. Ebewele, CRC Press, 2000 1 3. Chemical Bonding and Polymer Structure I. INTRODUCTION 8939/ch03/frame Page 60 Monday, April 3, 2006 2:42 PM In organic chemistry, the physical state of a homologous series (alkane series with the general formula [CnH2n+2]) changes as the molecular size increases. By moving from the low- to the high-molecular-weight end of the molecular spectrum, the physical60 states change progressively from the gaseous statePOLYMERthrough SCIENCEliquids AND TECHNOLOGYof increasing viscosity (decreasing volatility) to low melting solids and ultimately terminate in high- strength solids. Table 3.1 Change of State with Molecular Size for the Alkane [CnH2n+2] Series No. of Carbon Atoms Molecular State 1Methane — boiling point –162°C 2–4 Natural gas — liquefiable 5–10 Gasoline, diesel fuel — highly volatile, low viscosity liquid 10–102 Oil, grease — nonvolatile, high viscosity liquid 3 102–10 Wax — low melting solid 3 6 10 –10 Solid — high strength 2 on the other hand (with large electron affinity), can achieve a stable electronic configuration by gaining an extra electron. The loss of an electron by sodium results in a positively charged sodium ion, while the gain of an extra electron by the chlorine atom results in a negatively charged chloride ion: Na+ Cl→ Na+ + Cl− (Str. 1) The bonding force in sodium chloride is a result of the electrostatic attraction between the two ions. Ionic bonds are not common features in polymeric materials. However, divalent ions are known to act as cross-links between carboxyl groups in natural resins.
    [Show full text]
  • Synthesis of N-Alkyl Methacrylate Polymers with Pendant Carbazole Moieties and Their Derivatives
    JOURNAL OF ORIGINAL ARTICLE WWW.POLYMERCHEMISTRY.ORG POLYMER SCIENCE Synthesis of n-Alkyl Methacrylate Polymers with Pendant Carbazole Moieties and Their Derivatives Yuriy Bandera,1,2 Tucker M. McFarlane,1,2,3 Mary K. Burdette,1,2 Marek Jurca,1,2 Oleksandr Klep,1,2 Stephen H. Foulger 1,2,4 1Center for Optical Materials Science and Engineering Technologies, Advanced Materials Research Laboratories, Clemson University, 91 Technology Drive, Anderson, South Carolina 29625 2Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 3Sonoco Institute of Packaging Design and Graphics at Clemson University, Clemson University, Clemson, South Carolina 29634 4Department of Bioengineering, Clemson University, Clemson, South Carolina 29634 Correspondence to: S. H. Foulger (E-mail: [email protected]) Received 3 October 2018; Accepted 6 November 2018; published online 3 December 2018 DOI: 10.1002/pola.29285 ABSTRACT: New methacrylate monomers with carbazole moie- their effect on the energy profile, thermal, dielectric, and ties as pendant groups were synthesized by multistep synthe- photophysical properties when compared to the parent poly- ses starting from carbazoles with biphenyl substituents in the mer poly(2-(9H-carbazol-9-yl)ethyl methacrylate). According to aromatic ring. The corresponding polymers were prepared the obtained results, these compounds may be well suited for using a free-radical polymerization. The novel polymers memory resistor devices. © 2018 Wiley Periodicals, Inc. contain N-alkylated
    [Show full text]
  • Vertical Orientation of Liquid Crystal on Polystyrene Substituted with N-Alkylbenzoate-P-Oxymethyl Pendant Group As a Liquid Crystal Precursor
    polymers Article Vertical Orientation of Liquid Crystal on Polystyrene Substituted with n-Alkylbenzoate-p-oxymethyl Pendant Group as a Liquid Crystal Precursor Kyutae Seo and Hyo Kang * BK-21 Four Graduate Program, Department of Chemical Engineering, Dong-A University, 37 Nakdong-Daero 550 Beon-gil, Saha-gu, Busan 49315, Korea; [email protected] * Correspondence: [email protected]; Tel.: +82-51-200-7720; Fax: +82-51-200-7728 Abstract: We synthesized a series of polystyrene derivatives modified with precursors of liquid crystal (LC) molecules via polymer modification reactions. Thereafter, the orientation of the LC molecules on the polymer films, which possess part of the corresponding LC molecular structure, was investigated systematically. The precursors and the corresponding derivatives used in this study include ethyl-p-hydroxybenzoate (homopolymer P2BO and copolymer P2BO#, where # indicates the molar fraction of ethylbenzoate-p-oxymethyl in the side chain (# = 20, 40, 60, and 80)), n-butyl- p-hydroxybenzoate (P4BO), n-hexyl-p-hydroxybenzoate (P6BO), and n-octyl-p-hydroxybenzoate (P8BO). A stable and uniform vertical orientation of LC molecules was observed in LC cells fabricated with P2BO#, with 40 mol% or more ethylbenzoate-p-oxymethyl side groups. In addition, the LC molecules were oriented vertically in LC cells fabricated with homopolymers of P2BO, P4BO, P6BO, and P8BO. The water contact angle on the polymer films can be associated with the vertical orientation Citation: Seo, K.; Kang, H. Vertical of the LC molecules in the LC cells fabricated with the polymer films. For example, vertical LC ◦ Orientation of Liquid Crystal on orientation was observed when the water contact angle of the polymer films was greater than ~86 .
    [Show full text]
  • Signature Redacted Signature of Author
    Synthetic Polypeptide-Based Hydrogel Systems for Biomaterials by Mackenzie Marie Martin B.A. Chemistry, Mathematics Washington & Jefferson College, 2012 Submitted to the Department of Chemistry in Partial Fulfillment of the Requirements for the Degree of ARCVES MASSACHUSETTS IN E Master of Science in Chemistry OF TECHNOLOGY at the JUN 3 0 2014 Massachusetts Institute of Technology June 2014 JE3RARIES , 2014 Massachusetts Institute of Technology All Rights Reserved Signature redacted Signature of Author ... '4 Mackenzie M. Martin MIT Department of Chemistry May 14, 2014 Signature redacted Certified by............ Paula T. Hammond David H. Koch Professor in Engineering Thesis Advisor Accepted by............... Signature redacted ....... Robert-W-.Fi....eld...... Robert W. Field Chairman, Departmental Committee on Graduate Students Synthetic Polypeptide-Based Hydrogel Systems for Biomaterials by Mackenzie Marie Martin Submitted to the Department of Chemistry on May 14, 2014 in partial fulfillment of the requirements for the degree of Master of Science in Chemistry Abstract Hydrogels formed from synthetic polypeptides generated by ring opening polymerization (ROP) of a-amino acid N-carboxyanhydrides (NCAs) present a robust material for modeling the interaction between extracellular matrix (ECM) properties and cellular phenomena. The unique properties of the polypeptide backbone allow it to fold into secondary structures and the ability to modify the side chain presents the opportunity to display chemical functionalities that dictate cellular signaling. The ability to induce cells to form tissue is a chemical and engineering challenge due to the fact that cells need physical support in the form of a 3D scaffold with both chemical and mechanical signals. The Hammond group previously reported the combination of synthetic polypeptides with modified side chains available for click chemistry at quantitative grafting efficiencies.
    [Show full text]
  • Aromatic Polyamide Nonporous Membranes for Gas Separation Application
    e-Polymers 2021; 21: 108–130 Review Article Debaditya Bera#, Rimpa Chatterjee#, and Susanta Banerjee* Aromatic polyamide nonporous membranes for gas separation application https://doi.org/10.1515/epoly-2021-0016 received November 12, 2020; accepted January 10, 2021 1 Introduction Abstract: Polymer membrane-based gas separation is a High-performance polymeric materials exhibit several superior economical and energy-efficient separation tech- exciting properties, such as high thermal stability, che- nique over other conventional separation methods. Over mical resistance, low flammability, and excellent mechani- the years, different classes of polymers are investigated for cal properties, that make them useful for advanced tech- their membrane-basedapplications.Theneedtosearchfor nologies. Wholly aromatic polyamides (PAs) are a class of - new polymers for membrane based applications has been high-performance polymers that find applications in dif- a continuous research challenge. Aromatic polyamides ferent cutting-edge technologies, particularly in aerospace ( ) - PAs , a type of high performance materials, are known and military applications. Nevertheless, very high glass - for their high thermal and mechanical stability and excel transition temperatures of PAs, mostly above their thermal fi - lent lm forming ability. However, their insolubility and decomposition temperatures, and their low solubility in ffi - processing di culty impede their growth in membrane organic solvents resulted in processing difficulties and based applications. In this review, we will focus on the restricted many of their applications. Consequently, basic - - PAs that are investigated for membrane based gas separa and applied research is directed to enhance their proces- tions applications. We will also address the polymer sability and solubility and widen the possibility of their design principal and its effects on the polymer solubility industrial applications (1–5).
    [Show full text]