Hierarchical Nanostructures in Semifluorinated Norbornene Block Copolymers

Abstract

Structure and dynamics of two microphase-separated norbornene block copolymers containing one comb-like component are investigated by X-ray scattering, relaxation spectroscopy as well as differential scanning calorimetry. It is shown that two self-assembling processes on different length scales coexist for these copolymers leading to hierarchically structured systems. Microphase separation of both block copolymer components appears on a scale of 20-25 nm while norbornene main and long semifluorinated side chains of the comb-like block nanophase separate within their domains on a scale of about 3 nm. This hierarchical structure is accompanied by a complex relaxation behavior which is characterized by two glass transitions. The glass temperature of the block with long bulky side chains is expectedly lower due to internal plasticization. An additional relaxation process showing typical features of a dynamic glass transition is related to an independent dynamics in small nanodomains formed by long aggregated side chains similar to the findings for many other comb-like polymers. Indications for the disappearance of the nanophase separation of main and semifluorinated side chains at high temperatures are discussed.

Molecular Dynamics of Amphiphilic Random Copolymers in the Bulk: A 1H and 19F NMR Relaxometry Study

“…A similar behavior was also found for chemically different comb-like polymers. [37][38][39]73,74] Notably, for poly(n-alkyl methacrylates), Beiner et al [37] detected two distinct glass transitions: one at lower temperature, associated with the motions of the polyethylene-like side chains (α PE ), and the other (the primary glass transition) at higher temperature, associated with inter-conformational motions of the main chain. This behavior was explained with an intramolecular nanophase separation of incompatible main chains and side chains, by which the sufficiently long alkyl pendant segments self-assembled in distinct nanodomains.…”

“…They were previously shown to self‐assemble in prolate single‐chain nanostructures in water solutions . The investigation of the complex hierarchical phase organization of amphiphilic (co)polymers is challenging and in general requires the combination of different techniques . Valuable information can be gained from the study of polymer dynamics at molecular and supramolecular levels.…”

“…[34,35] The investigation of the complex hierarchical phase organization of amphiphilic (co)polymers is challenging and in general requires the combination of different techniques. [25,26,[36][37][38][39] Valuable information can be NMR Relaxometry A set of amphiphilic random copolymers of poly(ethylene glycol) methacrylate (PEGMA) and perfluorohexylethyl acrylate (FA) with different compositions synthesized by atom transfer radical polymerization (ATRP) is investigated by 1 H and 19 F NMR relaxometry. In particular, a thorough investigation of T 1 and T 2 relaxation times at variable temperature and copolymer composition provides the first complete and detailed characterization of the dynamics of both the main chain backbone and the side chains of the PEGMA-co-FA copolymers.…”

Retracted: Controlled synthesis of magnetic block copolymers for anti‐microbial purpose

“…27 An added benefit of block copolymers is that their chemical composition can be altered to obtain different mechanical properties and morphology without affecting the basic properties of the individual domains. 28,29 In the previous research, a series of paramagnetic polymers based on polyethyleneimine (PEI) were synthesized via quaternization and post-polymerization with FeCl 3 Á 6H 2 O, which indicated that the polymers was difficult to be film due to the nature of polymer electrolyte. 30 In order to obtain magnetic polymer films, a series of block copolymers containing alkyl substituted norbornene derivative and imidazolium chloride based norbornene derivative were prepared via ROMP and post-modification in this research.…”

Semifluorinated Methacrylate Random Copolymers: Phase Transitions and Molecular Dynamics

“…Results of molecular dynamics have been reported for sf alkanes [15][16], as well as for various polymers with attached sf chains as side chains either as homopolymers [17][18][19][20] or as copolymers [21][22][23]. The molecular mobility of the chain backbone, as well as that of the sf side chains, ranging from local to segmental motions was followed and related to 28/[282] S. Kripotou et al the structure of the systems.…”