Conformational Transition of End-Grafted Poly(di-<i>n</i>-hexylsilane) in Solventless Conditions

Furukawa, Katsuko; Ebata, Keisuke

doi:10.1021/ma011421j

Cited by 7 publications

(7 citation statements)

References 20 publications

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“…Poly(di- n -hexylsilane) (PDHS) is an example of a polysilane whose thermochromism has been observed in solution, in the solid state, and in the end-grafted state. Our previous study revealed that PDHS end-grafted on a quartz surface exhibits thermochromism in a vacuum, which is similar to that in dilute solution but different from that in a solid state . In this regard, the current observations agree with this earlier finding.…”

Section: Discussionsupporting

confidence: 91%

“…The state of the EG polysilanes would be different from those of an isolated polysilane in a dilute solution and a polysilane in the solid state. In fact, UV absorption spectra observations have revealed some unique EG polysilane behavior. 13a, Symmetrically alkyl-substituted polysilanes often exhibit clear thermochromism, and thus it is of interest to compare the thermochromic behavior under different conditions, namely, in dilute solution, in the solid state, and in the end-grafted state. It is also our concern to compare the solvatochromic behavior of the EG polysilanes with their thermochromic behavior.…”

Section: Introductionmentioning

confidence: 99%

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Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH₃)₂SiR₂]_n (R = C₂H₅, n-C₄H₉, n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁)

et al. 2003

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We synthesized a series of polysilanes -[Si(CH 3)2SiR2]n-[R ) C2H5, n-C4H9, n-C6H13, n-C8H17, n-C10H21] end-grafted on a quartz surface by utilizing the anionic polymerization of the corresponding source materials. We first confirmed that these symmetrically alkyl-substituted polysilanes exhibited reversible thermochromism in isooctane solution. When the polysilanes were end-grafted on the quartz surface, they also exhibited reversible thermochromism in a vacuum and reversible solvatochromism as the ratio of the isooctane/ethanol cosolvent was varied. In all of these experiments, we observed the transition between two clearly distinguishable phases. No side chain effect was observed for the peak wavelengths of the absorption band. However, the side chain effect appeared at a critical temperature and a critical cosolvent ratio for the transitions. The packing force between the alkyl chains in the highly ordered structure of the polysilane plays a dominant role in these transitions. We also discuss the difference in the transition behavior in solution, in the solid state, and in the end-grafted state.

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Section: Discussionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH₃)₂SiR₂]_n (R = C₂H₅, n-C₄H₉, n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁)

et al. 2003

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“…Measurements of thermochromism, namely the reversible spectral change that depends on temperature, of 5b revealed that end-grafted 1b under poor solvent conditions behaves similarly to 1b in dilute solution but not to the solid thin film of 1b. 25 Figure 9 shows the temperature-dependent electronic absorption spectra of 5b in a vacuum. There is an absorption band peaking at 316 nm at 300 K, which is characteristic of the σ-σ* transition of 1b.…”

Section: Thermochromism: Test Of Intermolecular Interaction-free Beha...mentioning

confidence: 99%

End-Grafted PolysilaneAn Approach to Single Polymer Science

Furukawa

2002

Acc. Chem. Res.

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This Account describes our approach to single polymer science in which we use end-grafted polysilane. Single polymer science, by our definition, involves isolating and observing a single polymer chain and extracting its physical properties at the single molecule level. For this purpose, we developed the end-graft technique, which is a method for fixing a polymer terminus on a solid surface by forming a chemical bond between them. We applied this technique to polysilane, a semiconducting polymer with a one-dimensional silicon-catenated backbone. Our recent experimental achievements are reviewed, which include direct observations of polysilane single-molecular structures by atomic force microscopy, the formation of unique supramolecular structures, and the observation of temperature- and solvent-dependent UV absorption spectra that are characteristic of isolated polysilane chains end-grafted on a solid surface.

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“…On cooling, PDBS and PDHS in solution suddenly change their λ max value from ca. 320 to 355 nm at −36 and −31 °C, respectively. , A similar phenomenon was observed from an end-grafted PDHS film . The 〈|φ|〉 value corresponding to λ max = 355 nm can be estimated from Figure as ca.…”

Section: Discussionmentioning

confidence: 95%

Conformational Analysis of Poly(di-n-butylsilane), Poly(di-n-hexylsilane), and Poly(methyl-n-propylsilane) by a Rotational Isomeric State Scheme with Molecular Dynamics Simulations

2003

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Conformational characteristics of poly(di-n-butylsilane) (PDBS), poly(di-n-hexylsilane) (PDHS), and poly(methyl-n-propylsilane) (PMPrS) have been investigated by a rotational isomeric state (RIS) scheme with molecular dynamics simulations. Characteristic ratios thus calculated for PDBS, PDHS, and atactic PMPrS are, respectively, 42.0, 54.0, and 12.3, being comparable to our light-scattering measurements. In the ϑ state, most Si−Si bonds of PDBS and PDHS adopt deviant ± (D±) conformations (dihedral angles ≈ ±150°); in adjacent Si−Si bonds, D±D± conformations are the most stable, and D±D∓ states have a slightly higher energy of ca. 0.1 kcal mol-1. This is the reason for their rigidity in solution and the formation of a disordered structure. An RIS treatment for pseudoasymmetric polymers with different side chains (R and R‘) (e.g., [-SiRR‘-] x and [-CRR‘-] x ) has been developed. By this method, the characteristic ratio of atactic PMPrS was obtained as above, and the stereosequence dependence of the spatial configuration of PMPrS was investigated; the characteristic ratio increases with the meso-diad probability. The UV absorption maxima (λmax) of PDBS, PDHS, and PMPrS were correlated with average dihedral angles evaluated from the RIS calculations. The solubility of polysilanes has also been elucidated in terms of conformation.

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Conformational Transition of End-Grafted Poly(di-n-hexylsilane) in Solventless Conditions

Cited by 7 publications

References 20 publications

Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH₃)₂SiR₂]_n (R = C₂H₅, n-C₄H₉, n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁)

Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH₃)₂SiR₂]_n (R = C₂H₅, n-C₄H₉, n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁)

End-Grafted PolysilaneAn Approach to Single Polymer Science

Conformational Analysis of Poly(di-n-butylsilane), Poly(di-n-hexylsilane), and Poly(methyl-n-propylsilane) by a Rotational Isomeric State Scheme with Molecular Dynamics Simulations

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Conformational Transition of End-Grafted Poly(di-n-hexylsilane) in Solventless Conditions

Cited by 7 publications

References 20 publications

Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH3)2SiR2]n (R = C2H5, n-C4H9, n-C6H13, n-C8H17, n-C10H21)

Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH3)2SiR2]n (R = C2H5, n-C4H9, n-C6H13, n-C8H17, n-C10H21)

End-Grafted PolysilaneAn Approach to Single Polymer Science

Conformational Analysis of Poly(di-n-butylsilane), Poly(di-n-hexylsilane), and Poly(methyl-n-propylsilane) by a Rotational Isomeric State Scheme with Molecular Dynamics Simulations

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Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH₃)₂SiR₂]_n (R = C₂H₅, n-C₄H₉, n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁)

Side Chain Effect on Thermochromism and Solvatochromism of End-Grafted Polysilane [Si(CH₃)₂SiR₂]_n (R = C₂H₅, n-C₄H₉, n-C₆H₁₃, n-C₈H₁₇, n-C₁₀H₂₁)