Two-Dimensional Piezochromism and Orientational Modulations in Polysilane Monolayer

Yoshida, Masaru; Nakanishi, Fusae; Seki, Takahiro; Sakamoto, Kenkichi; Sakurai, Hideki

doi:10.1021/ma961721e

Cited by 24 publications

(24 citation statements)

References 18 publications

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“…44 A strong red shift of the A-band and additional bands have also been found for alkylsubstituted poly(thiophene)s in LB and spin-coated films and were attributed to a planarization of the polymer backbone. 47 The shape and maximum of the A-band of conjugated aromatic or heteroaromatic polymers can also be shifted by the formation of aggregates.…”

Section: Resultsmentioning

confidence: 79%

Piezochromic Effect and Orientational Order in Monolayers and LB Multilayers of Poly(p-phenylenesulfonate)− Dioctadecyldimethylammonium Bromide Complexes

2000

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By spreading dioctadecyldimethylammonium bromide (DODA) on a subphase containing rigid-rod-like poly(p-phenylenesulfonate)s (PPPS), polyelectrolyte complexes are formed in situ at the air-water interface. These complex monolayers are investigated by recording surface pressure/area isotherms, UV/vis spectroscopy, and, after transfer onto a solid substrate, X-ray photoelectron spectroscopy (XPS) and X-ray reflectivity (XR). XPS and XR measurements indicate that although the polyelectrolytes are aggregated in aqueous solution, the complexes are stoichiometric. The isotherms show that the area per amphiphile in the complex monolayer is significantly higher than in the monolayer of pure DODA. This is due to the distance of the ionic sites along the rigid-rod-like polymer chain and results in a more tilted arrangement of the alkyl chains as confirmed by the XR measurements. UV/vis spectroscopy reveals that the A-band of the PPPS is red-shifted in the complex, and a further red shift of the A-band upon compression of the complex monolayer is observed. This two-dimensional piezochromic effect is discussed to be a result of the electronic interaction of the π-systems, which improves with decreasing distance during compression. Upon transfer to solid substrates the rigid-rod-like polyelectrolytes are oriented to be parallel to the dipping direction as evidenced by polarized UV/vis spectroscopy. The degree of order in the LB film shows a linear dependence on the axial ratio of the rigid-rod-like PPPS.

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Section: Resultsmentioning

confidence: 79%

Piezochromic Effect and Orientational Order in Monolayers and LB Multilayers of Poly(p-phenylenesulfonate)− Dioctadecyldimethylammonium Bromide Complexes

2000

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“…As described in the introduction, several past studies have demonstrated that in-plane alignment of polymer backbones can be induced by uniaxial compression of Langmuir films of polymers at aqueous-air interfaces 31–39. We note further, however, that these past reports have generally made use of polymers with rigid structures and/or other properties that facilitated characterization of the anisotropic nature of the Langmuir films.…”

Section: Resultsmentioning

confidence: 85%

“…The results of these investigations, when combined, lead us to conclude that uniform azimuthal alignment of 5CB is the result of long-range ordering of the polymer chains in the Langmuir films that is generated during uniaxial compression of the films prior to LS transfer. Although past studies of Langmuir films of polymers at aqueous-air interfaces reported by other groups have demonstrated that in-plane alignment of polymer backbones can be induced by uniaxial compression, these past reports have generally been restricted to the characterization of rigid rod-type polymers,31–35 polypeptides that form helical structures,36–38 or piezochromic polysilanes39 that are rigid and/or possess chromophores that facilitate characterization of the anisotropic nature of the Langmuir films (e.g., using methods such as polarized absorbance spectroscopy). One important outcome of this current study is thus the observation of anisotropy and long-range order in Langmuir films of a novel flexible polymer.…”

Section: Introductionmentioning

confidence: 99%

Langmuir films of flexible polymers transferred to aqueous/liquid crystal interfaces induce uniform azimuthal alignment of the liquid crystal

Kinsinger

Buck

Meli

et al. 2010

Journal of Colloid and Interface Science

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We reported recently that amphiphilic polymers can be assembled at interfaces created between aqueous phases and thermotropic liquid crystals (LCs) in ways that (i) couple the organization of the polymer to the order of the LC and (ii) respond to changes in the properties of aqueous phases that can be characterized as changes in the optical appearance of the LC. This investigation sought to characterize the behavior of aqueous-LC interfaces decorated with uniaxially compressed thin films of polymers transferred by Langmuir-Schaefer (LS) transfer. Here, we report physicochemical characterization of interfaces created between aqueous phases and the thermotropic LC 4-cyano-4'-pentylbiphenyl (5CB) decorated with Langmuir films of a novel amphiphilic polymer (polymer 1), synthesized by the addition of hydrophobic and hydrophilic side chains to poly(2-vinyl-4,4'-dimethylazlactone). Initial characterization of this system resulted in the unexpected observation of uniform azimuthal alignment of 5CB after LS transfer of the polymer films to aqueous-5CB interfaces. This paper describes characterization of Langmuir films of polymer 1 hosted at aqueous-5CB interfaces as well as the results of our investigations into the origins of the uniform ordering of the LC observed upon LS transfer. Our results, when combined, support the conclusion that uniform azimuthal alignment of 5CB is the result of long-range ordering of polymer chains in the Langmuir films (in a preferred direction orthogonal to the direction of compression) that is generated during uniaxial compression of the films prior to LS transfer. Although past studies of Langmuir films of polymers at aqueous-air interfaces have demonstrated that in-plane alignment of Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.Supporting Information Available. Additional figures and other data showing: (i) surface pressure recorded during repeated compression and expansion of a Langmuir film of polymer 1, (ii) a fluorescent micrograph of a film of 5CB after Langmuir-Schafer transfer of polymer 1 TMR to the aqueous-5CB interface, (iii) a representative AFM image of a film of polymer 1 transferred to an OTScoated Si substrate, (iv) polarized light micrographs of a LC film after transfer of polymer 1 at an angle ~ 45° relative to the aqueous-air interface, (v) fractional transmittance of polarized light through polymer 1-laden LC interfaces transferred at various angles relative to the direction of compression, (vi) representative π-A isotherms of Langmuir films of PMMA and PVS, (vii) polarized FT-IR spectra of PMMA films on CaF 2 substra...

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“…Stimuli responsive smart materials exist in nature 1 , and have been extensively designed including photochromic 2,3 , halochromic 4,5 , piezochromic 6,7 and thermochromic 8–11 materials. Thermochromic materials, which alter color in response to changes in temperature, have gained attention 12–14 , varying from inorganic 15 to organic 16 and find a plethora of applications such as labels, sensors, toys and space satellite coating 17,18 .…”

Section: Introductionmentioning

confidence: 99%

Reversible Micro- and Nano- Phase Programming of Anthraquinone Thermochromism Using Blended Block Copolymers

Zhang

Lovell

2015

Langmuir

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Here, we present an approach to generate materials with programmable thermochromic transition temperatures (TTTs), based on the reversible microcrystallization of anthraquinone dyes with the assistance of blended Pluronic block copolymers. At temperatures above block copolymer critical micellization temperature (CMT), hydrophobic anthraquinone dyes, including sudan blue II, were dispersed in copolymer micelles, whereas at lower temperature, the dyes formed microcrystals driven by the dye-dye and dye-Pluronic molecular interactions. The crystallization process altered the optical properties of the dye with bathochromatic shifts detectable by eye and the thermochroic process was fully reversible. Not only could Pluronic reversibly incorporate the anthraquinone dyes into micelles at elevated temperatures, but it also modulated the crystallization process and resulting morphology of microcrystals via tuning the molecular interactions when the temperature was lowered. Crystal melting transition points (and TTTs) were in agreement with the CMTs, demonstrating that the thermochromism was dependent on block copolymer micellization. Thermochromism could be readily programmed over a broad range of temperatures by changing the CMT by using different types and concentrations of Pluronics and combinations thereof.

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Two-Dimensional Piezochromism and Orientational Modulations in Polysilane Monolayer

Cited by 24 publications

References 18 publications

Piezochromic Effect and Orientational Order in Monolayers and LB Multilayers of Poly(p-phenylenesulfonate)− Dioctadecyldimethylammonium Bromide Complexes

Piezochromic Effect and Orientational Order in Monolayers and LB Multilayers of Poly(p-phenylenesulfonate)− Dioctadecyldimethylammonium Bromide Complexes

Langmuir films of flexible polymers transferred to aqueous/liquid crystal interfaces induce uniform azimuthal alignment of the liquid crystal

Reversible Micro- and Nano- Phase Programming of Anthraquinone Thermochromism Using Blended Block Copolymers

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