Azobenzene modified poly(aryl ether ketone amide)s. 2. Photo- and thermo-responsive behaviour in dilute solution

Beattie, Margaret S.; Jackson, Christian; Jaycox, Gary D.

doi:10.1016/s0032-3861(97)00559-4

Cited by 28 publications

(18 citation statements)

References 24 publications

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“…Importantly, cis-isomer half-life values determined at room temperature for all of the polymers exceeded 100 h, allowing for the acquisition of chiroptical data over short time periods that were uncomplicated by rapidly shifting cis-trans isomer populations within the polymer backbones. As observed for other azobenzene modified copolyaramides synthesized in our laboratory, 4,6,8,13 the interconversion of trans-and cisisomeric states within these constructs was completely reversible over numerous isomerization cycles without any apparent hysteresis or photodegradation effects.…”

Section: Photophysical Behaviorsupporting

confidence: 71%

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Stimuli-Responsive Polymers VI. Azobenzene Modified Copolyaramides with Chiral Helical Geometries: Influence of Rigid, Helix-Disrupting Segments on Physiochemical and Chiroptical Behavior

Jaycox

2002

Polym J

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ABSTRACT:Polymers comprised of alternating trans-4,4 -azobenzene and helix directing (R)-2,2 -binaphthylene backbone linkages adopt single handed helical conformations in solution that are reversibly distorted by light and heat regulated trans ↔ cis isomerization processes. The replacement of (R)-binaphthylene backbone groups with helixdisrupting 4,4 -diphenylfluorene segments affords permanent changes in some of the properties exhibited by this family of optically active materials. Polymer solubilities in organic solvents like THF and acetone are significantly diminished while thermal stabilities and photophysical behavior remain largely unchanged. Optical rotation magnitudes measured at the sodium D-line drop in a linear manner with the loss of the atropisomeric binaphthylene linkages. However, all of the polymer variants exhibit stimuli-responsive chiroptical behavior when evaluated in DMAC or THF solution environments. Specific rotation magnitudes are reversibly diminished by the near-UV light induced trans → cis isomerization reaction. Optical rotatory power is restored by reverse cis → trans isomerization processes triggered by heat or by visible light illumination. That stimuli-responsive chiroptical properties are exhibited by all polymer variants regardless of their monomer compositions indicates that global helical order along the polymer backbone is not necessarily required for this effect. Rather, isomerization induced perturbations to the local dihedral angles residing in the atropisomeric binaphthylene main chain segments likely serve as the genesis for photo-and thermo-regulated behavior in these materials.KEY WORDS Stimuli-Responsive Chiroptical Behavior / trans-cis Azobenzene Isomerization / Helical Polymers / Circular Dichroism / Optical Rotation / Exciton Coupling / Cardo Polymers / Macromolecules endowed with single-handed helical geometries can be prepared by a variety of synthetic methods. Monomers based on chiral 1,1 -binaphthylenes, 1,1 -biphenylenes and other axially dissymmetric ring systems provide convenient access to condensation polymers with chiral helical motifs. The polycondensation of (R)-(+)-1,1 -binaphthyl-2,2 -diamine with terephthaloyl chloride was first reported by Schulz and Jung over thirty years ago. 1 The resulting polyaramide exhibited significant optical rotatory power that was attributed to the presence of a single helical screw sense along the polymer's conformationally restricted backbone. In the decades that have followed, a variety of other optically active macromolecules have been assembled from atropisomeric, helix-directing monomers using this same generalized approach. 2 Earlier, this laboratory reported the preparation of a number of helical trans-azobenzene modified polyaramides from both (R)-and (S )-1,1 -binaphthyl-2,2 -diamine. 3, 4 Some of these materials were specifically designed to undergo reversible helix order ↔ disorder transitions in response to multiple trans ↔ cis azobenzene isomerization reactions triggered within the polymer's main chain. [5]...

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Section: Photophysical Behaviorsupporting

confidence: 71%

“…Backbone compositions for this trans-polymer series were carefully determined by 1 H NMR spectroscopy 13 by integrating appropriate amide proton signals falling between 10.0 and 10.5 ppm (DMSO-d 6 ). Compositional data are provided in Scheme 1 (mol%) and in Table I (weight%) for comparison.…”

Section: Polymer Synthesesmentioning

confidence: 99%

Stimuli-Responsive Polymers VI. Azobenzene Modified Copolyaramides with Chiral Helical Geometries: Influence of Rigid, Helix-Disrupting Segments on Physiochemical and Chiroptical Behavior

Jaycox

2002

Polym J

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“…10 In contrast, photocontractions in a related series of polymers modified with flexible octamethylene chain segments were reduced by a full order of magnitude when examined under the same experimental conditions.…”

Section: Introductionmentioning

confidence: 95%

“…Recently, we reported the synthesis 9 and photophysical evaluation 10 of a new series of azobenzene-modified poly(aryl ether ketone amide)s having enhanced organosolubilities:…”

Section: Introductionmentioning

confidence: 99%

Stimuli-responsive polymers. III. Poly(aryl ether ketone amide)s with reversibletrans- ?cis-4,4?-azobenzene and fixed 2,2?-binaphthyl kinking elements in the main chain

Howe

Jaycox

1998

J. Polym. Sci. A Polym. Chem.

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“…That one configurational isomer is furnished photo-chemically while the other is favored thermally makes it possible to effectively drive or 'switch' azobenzene-modified species into a desired geometry and polarity. Thus, incorporation of azobenzene moieties into polymers might bring remarkable photo-and thermo-regulated behavior when subjected to changes in incident light or heat [33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Characterization and Thermally-Activated Curing of Azobenzene-Containing Benzoxazines

Kışkan

Dogan

Durmaz

et al. 2008

Designed Monomers and Polymers

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Two new benzoxazine monomers with aliphatic and aromatic substituents, as well as azobenzene moieties were synthesized and characterized by spectroscopic methods. Their thermal curing behavior in the absence of any catalyst was investigated by differential scanning calorimetry. The thermal properties of the crosslinked structures were also studied by thermogravimetric analysis. While the monomeric forms gave some indication of thermally-induced isomerization, the azo groups were shown to be fixed in the disordered form in the densely cross-linked matrix.

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Azobenzene modified poly(aryl ether ketone amide)s. 2. Photo- and thermo-responsive behaviour in dilute solution

Cited by 28 publications

References 24 publications

Stimuli-Responsive Polymers VI. Azobenzene Modified Copolyaramides with Chiral Helical Geometries: Influence of Rigid, Helix-Disrupting Segments on Physiochemical and Chiroptical Behavior

Stimuli-Responsive Polymers VI. Azobenzene Modified Copolyaramides with Chiral Helical Geometries: Influence of Rigid, Helix-Disrupting Segments on Physiochemical and Chiroptical Behavior

Stimuli-responsive polymers. III. Poly(aryl ether ketone amide)s with reversibletrans- ?cis-4,4?-azobenzene and fixed 2,2?-binaphthyl kinking elements in the main chain

Synthesis, Characterization and Thermally-Activated Curing of Azobenzene-Containing Benzoxazines

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