DOCSLIB.ORG

Caged Polyphosphazenes with a Visible‐

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read 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 in There is considerable demand for stimuli-responsive polymers various fields such as medicine, polymer science, cosmetics, that can undergo chemical or physical changes in response to and biology.[12] Coumarin derivatives can be readily synthesized triggers such as pH,[1] biomolecules,[2] temperature, oxidation,[3] and functionalized to red-shift the light absorption,[12] cage the and light.[4] Macromolecules which undergo triggered backbone desired molecule as protecting groups,[13] and/or to be incorpo- disassembly or degradation upon response to stimuli could be of rated on the polymer main chain as photoresponsive units.[14] particular importance for a range of future applications including It is also reported that coumarin photocages can be cleaved via sensory materials, lithography, and triggered release systems.[5] two-photon processes with near-infra-red irradiation.[15] In addi- One approach involves self-immolative polymers[6] which are tion, functionalized aliphatic polycarbonates,[16] photodegradable designed to undergo end-to-end disassembly upon a triggering hydrogels,[17] and drug delivery systems[18] based on coumarin event.[7] More recently, a small number of chain-shattering poly- derivatives have been developed. Furthermore, the ability of some mers have been described, a term used to describe polymers coumarin polyesters to undergo chain scission or crosslinking with multiple responsive cleavage sites along the backbone.[3b,8] upon certain wavelength irradiation has been demonstrated.[14,19] Among the investigated stimuli, light is notably attractive Herein, we present a novel approach to photodegradable due to its ability to exert spatial and temporal control over the polymers based on coumarin-functionalized polyphospha- zenes. Polyphosphazenes are unique due to their hydrolytically Dr. A. Iturmendi, D. Maderegger, Prof. I. Teasdale unstable backbone which can be tailored through the incorpo- Institute of Polymer Chemistry ration of different substituents.[20] Furthermore, the polyphosp- Johannes Kepler University Linz hazene degradation pathway is known to be acid-catalyzed,[21] a Altenberger Strasse 69, 4040 Linz, Austria E-mail: [email protected] process which can be intramolecular when acidic substituents [22] Dr. S. Theis are present on the polymer backbone. Hence we proposed Institute of Inorganic Chemistry that through functionalization of polyphosphazenes with a Johannes Kepler University Linz coumarin-caged amino acid as a pendant group along the back- Altenberger Strasse 69, 4040 Linz, Austria bone, the sensitivity of the polymers to hydrolysis would be Prof. U. Monkowius accelerated upon irradiation by effectively producing a macro- Linz School of Education molecular photoacid which could subsequently catalyze its own Johannes Kepler University Linz Altenberger Strasse 69, 4040 Linz, Austria degradation. The ORCID identification number(s) for the author(s) of this article First 7-(N,N-diethylamino)-4-(hydroxymethyl)coumarin 1 can be found under https://doi.org/10.1002/marc.201800377. (Figure S1, Supporting Information) was prepared according [15] © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, to literature procedures. After reaction with N-(tert-butox- Weinheim. This is an open access article under the terms of the Creative ycarbonyl)glycine (Boc-gly-OH) and deprotection, this gave Commons Attribution License, which permits use, distribution and re- the coumarin-caged glycine 3 (Figures S2 and S3, Supporting production in any medium, provided the original work is properly cited. Information).[23] Coumarin 1 was chosen as caging group as it DOI: 10.1002/marc.201800377 is expected to be photochemically active in the visible region Macromol. Rapid Commun. 2018, 39, 1800377 1800377 (1 of 6) © 2018 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.advancedsciencenews.com www.mrc-journal.de Figure 1. a) Photocleavage reaction of the coumarin-caged glycine 3. b) Change of the emission spectra of 3 in MeOH/H2O (4:1) solution upon irra- diation with HBO lamp (100 W, cut-off filter at 395 nm, conc. 10−7 mol L−1). (— before irradiation; …5 min irradiation; ¨10 min irradiation; •15 min 1 −1 1 irradiation; -- 25 min irradiation). c) H NMR analysis of the photocleavage of 3 in MeOD/D2O (4:1) solution (conc. 0.082 mol L ). Entire H NMR spectra are shown in Figure S5, Supporting Information. due to the electron-donating diethylamino group.[24] The chlorine atoms were substituted with either Jeffamine M-1000, kinetics of the elementary photochemical reaction of 3 has been a polyether monoamine, or glycine ethyl ester to obtain pol- investigated recently by flash-photolysis[23] but not under steady ymer P1 and polymer P2, respectively. illumination. Hence, we first investigated the photo-cleavage Polymer P1 was synthetized using Jeffamine M-1000 as the reaction of compound 3 upon irradiation (100 W, ≥395 nm) second substituent to give a water-soluble polymer. M-1000 in MeOH/H2O (4:1) solution. UV–vis spectroscopy (Figure S4, was also chosen to ensure that the hybrid polymer remained Supporting Information) showed a decrease in absorption hydrolytically stable in the timeframe of the photochemical intensity and shifted to lower wavelength (from 382 to 377 nm) reactions[21] and hence to be able to induce a photochemical after irradiation, indicative of the decaging of the glycine moiety degradation without significant interference from undesired (Figure 1a). Interestingly, an increase in intensity and slight hydrolytic degradation. The polymer was purified by dialysis hypsochromic shift (from 478 to 473 nm) was observed in the in the dark and characterized by 1H and 31P NMR spectros- emission spectra upon irradiation (Figure 1b). This ceased after copy (Figure S6, Supporting Information), size exclusion chro- approximately 25 min irradiation, indicating completion of the matography (SEC) in DMF containing 10 mM LiBr (Figure S7, 1 −1 photosolvolysis reaction. H NMR spectroscopy (Figure 1c) also Supporting Information, Mn,GPC = 149 000 g mol , and confirmed the nature of the photocleavage reaction, albeit with Mw/Mn = 1.03, measured using multidetector calibration) and a lower reaction rate due to the higher concentration required dynamic light scattering (DLS) (Figure S8, Supporting Informa- −7 −1 −1 −1 (10 mol L vs 0.082 mol L ). tion, d = 12.25 nm ± 0.38 nm in H2O at 1 mg mL ). According Our approach was to extend this photodecaging phenom- to 1H and 31P NMR spectroscopy complete backbone substi- enon to “cage” a hydrolytically unstable glycine-substituted tution in a ratio of nearly 34:66 (coumarin derivative:M-1000) phosphazene moiety through incorporation of the coumarin- could be observed with no additional peaks in the 31P NMR caged glycine onto a polyphosphazene backbone. Polydichlo- corresponding to partially substituted phosphorous atoms. rophosphazene was first prepared via phosphine-mediated UV–vis spectroscopy (Figure S9, Supporting Information) polymerization of trichlorophosphoranimine[25] (Scheme 1, showed the loading to be approximately 14 wt%, which corre- see Supporting Information for detailed procedure). First, the sponds roughly to 35:65 ratio, coumarin derivative to M-1000 coumarin-cage 3 was added in order to substitute the majority substituents. of chlorine atoms. For related amino acid esters, it is known The polymer was irradiated (100 W, ≥395 nm) in aqueous that monosubstitution at the phosphorus atom is strongly solution to investigate its photochemical properties. The photo- favored due to the higher reactivity of Cl2PN in comparison reaction was followed by UV–vis (Figure 2a) and fluorescence to ClRPN,[26] therefore, we expect a distribution of the cou- spectroscopy (Figure 2b). In the UV–vis spectra, one prominent marin groups along the backbone. Thereafter, the remaining long wavelength absorption band with a maximum at 386 nm Macromol. Rapid Commun. 2018, 39, 1800377 1800377 (2 of 6) © 2018 The
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]
  • 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]
  • 1 Glass-Transition Phenomena in Polymer Blends Ioannis M
    1 1 Glass-Transition Phenomena in Polymer Blends Ioannis M. Kalogeras University of Athens, Faculty of Physics, Department of Solid State Physics, Zografos 15784, Greece 1.1 Introduction The ever-increasing demand for polymeric materials with designed multi- functional properties has led to a multiplicity of manufacturing approaches and characterization studies, seeking proportional as well as synergistic properties of novel composites. Fully integrated in this pursuit, blending and copolymerization have provided a pair of versatile and cost-effective procedures by which materials with complex amorphous or partially crystalline structures are fabricated from combinations of existing chemicals [1–3]. Through variations in material’scom- position and processing, a subtle adaptation of numerous chemical (corrosion resistance, resistance to chemicals, etc.), thermophysical (e.g., thermal stability, melting point, degree of crystallinity, and crystallization rate), electrical or dielectric (e.g., conductivity and permittivity), and manufacturing or mechanical properties (dimensional stability, abrasion resistance, impact strength, fracture toughness, gas permeability, recyclability, etc.) can be accomplished effortlessly. It is therefore not surprising the fact that related composites have been widely studied with respect to their microstructure (e.g., length scale of phase homoge- neity in miscible systems, or type of the segregation of phases in multiphasic materials) and the evolution of their behavior and complex relaxation dynamics as
    [Show full text]