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Title: Shape-Persistent, Thermoresponsive Polypeptide Brushes Prepared by Vapor Deposition Surface-Initiated Ring-Opening Polymerization of α-Amino Acid N -Carboxyanhydrides

We report that surface-grafting thermoresponsive polymers allows the preparation of thin polymer brush coatings with surface properties that can be manipulated by variation of temperature. In most instances, thermoresponsive polymer brushes are produced using polymers that dehydrate and collapse above a certain temperature. This report presents the preparation and properties of polymer brushes that show thermoresponsive surface properties, yet are shape-persistent in that they do not undergo main chain collapse. The polymer brushes presented here are obtained via vapor deposition surface-initiated ring-opening polymerization (SI-ROP) of γ-di- or tri(ethylene glycol)-modified glutamic acid N-carboxyanhydrides. Vapor deposition SI-ROP of γ-di- or tri(ethylene glycol)-modified L- or D-glutamic acid N-carboxyanhydrides affords helical surface-tethered polymer chains that do not show any changes in secondary structure between 10 and 70 °C. QCM-D experiments, however, revealed significant dehydration of poly(γ-(2-(2-methoxyethoxy)ethyl)-l-glutamate) (poly(L-EG 2-Glu)) brushes upon heating from 10 to 40 °C. At the same time, AFM and ellipsometry studies did not reveal significant variations in film thickness over this temperature range, which is consistent with the shape-persistent nature of these polypeptide brushes and indicates that the thermoresponsiveness of the films is primarily due to hydration and dehydration of the oligo(ethylene glycol) side chains. The results we present here illustratemore » the potential of surface-initiated NCA ring-opening polymerization to generate densely grafted assemblies of polymer chains that possess well-defined secondary structures and tunable surface properties. These polypeptide brushes complement their conformationally unordered counterparts that can be generated via surface-initiated polymerization of vinyl-type monomers and represent another step forward to biomimetic surfaces and interfaces.« less
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [3] ;  [1] ;  [2]
  1. Chinese Academy of Sciences (CAS), Beijing (China). Inst. of Chemistry. Beijing National Lab. for Molecular Sciences (BNLMS)
  2. Ecole Polytechnique Federale Lausanne (Switzlerland). Inst. of Materials and Chemical Sciences and Engineering, Polymer Lab.
  3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry and Chemical & Biomolecular Engineering
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science (CNMS)
Publication Date:
Grant/Contract Number:
AC05-00OR22725; 1133320
Type:
Accepted Manuscript
Journal Name:
Macromolecules
Additional Journal Information:
Journal Volume: 48; Journal Issue: 8; Journal ID: ISSN 0024-9297
Publisher:
American Chemical Society
Research Org:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
Sponsoring Org:
USDOE Office of Science (SC); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; thermoresponsive polymers; polymer brushes; shape-persistent
OSTI Identifier:
1265722