A Detailed UV and Raman Study of Poly(<i>n</i>-butyl-<i>n</i>-hexylsilylene) Phase Transitions

Bukalov, Sergey S.; Leites, L. A.; West, Robert; Asuke, Tetsuya

doi:10.1021/ma950872z

Cited by 36 publications

(23 citation statements)

References 17 publications

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“…1 Comparison of the WAXD data and the UV, Raman (λ exc =514.5 nm) and IR spectra obtained at room temperature for the very same thin film of the polymer [ n Hex 2 Si] n deposited on a CsI substrate [18] those with disordered, all-D and all-A conformations of the backbone, are involved. Sometimes intermediate polymorphs are also found [14,21].…”

Section: Characterization Of Thermochromic Ptmentioning

confidence: 99%

“…1, the film of [ n Hex 2 Si] n at room temperature is seen to contain two forms: the hcm with a disordered backbone and the crystalline phase with the all-A backbone, the latter being predominant. Sometimes TPT can involve not only two but more modifications; e.g., in the cases of [ n Pent 2 Si] n [22,23,27,28] and [ n BuSi n Hex] n [12,14] three modifications, Fig. 1 Comparison of the WAXD data and the UV, Raman (λ exc =514.5 nm) and IR spectra obtained at room temperature for the very same thin film of the polymer [ n Hex 2 Si] n deposited on a CsI substrate [18] those with disordered, all-D and all-A conformations of the backbone, are involved.…”

Section: Characterization Of Thermochromic Ptmentioning

confidence: 99%

“…[14], (b) high molecular weight [ n Pent 2 Si] n [23] According to the second model, over time the UV bands at 350 and~365 nm should disappear, being replaced by the band at~375 nm. However, below T c under the conditions of non-equilibrium cooling, molecular motions are sluggish, and metastable modifications can exist for an indefinitely long time [39][40][41][42][43].…”

Section: Uv Criteria Of Assignment Of Polysilane Modificationsmentioning

confidence: 99%

“…The aim of this paper is to describe characteristic features of polydi-n-alkylsilane transitions based on generalization from the authors' experience [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] and literature data, as well as to demonstrate that the three types of ordering are not necessarily interrelated.…”

Section: Introductionmentioning

confidence: 99%

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Regularities and Peculiarities of Solid Polydialkylsilane Order-Disorder Transitions as Studied by Optical (UV, Raman and IR) Spectroscopy

Bukalov

Leites

West³

2010

Silicon

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As a result of systematic studies of numerous polydi-n-alkylsilane order-disorder transitions using a combination of UV, Raman, IR as well as XRD methods some generalizations are made concerning the nature of these processes. A criterion is proposed for a given UV band assignment to a given polymer modification based not only on its λ max value but also on the band width, contour and temperature behaviour of these parameters. Three types of ordering possible for these polymers were shown not to be necessarily interrelated. Side chain "melting" does not inevitably lead to thermochromism while thermochromic structural transitions can occur within the same phase.

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Section: Characterization Of Thermochromic Ptmentioning

confidence: 99%

Section: Characterization Of Thermochromic Ptmentioning

confidence: 99%

Section: Uv Criteria Of Assignment Of Polysilane Modificationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Regularities and Peculiarities of Solid Polydialkylsilane Order-Disorder Transitions as Studied by Optical (UV, Raman and IR) Spectroscopy

Bukalov

Leites

West³

2010

Silicon

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“…For instance, a polysilane [ n BuSi n Hex] n at room temperature forms the so-called hexagonal columnar mesophase (hcm), in which the polymer macromolecules have disordered conformations but each macromolecule is as if inscribed into a virtual cylinder. 61 A broad UV absorption band with max at 320 nm corresponds to this state of the polymer. This means that the e value with usual excitation in the red/blue region lies within the pre-resonance limits 15 000-10 000 cm 1 .…”

Section: S-s Conjugationmentioning

confidence: 99%

Raman intensity and conjugation with participation of ordinary σ‐bonds

Leites

Bukalov

2001

J Raman Spectroscopy

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This review covers Raman investigations over a wide range, but focused on the problem of conjugation with participation of ordinary s-bonds. The results show that s-s conjugation in a novel class of polymers, polydiakylmetallanes of the type [R 2 M] n , M = Si, Ge, Sn, studied recently, and s-p conjugation in some organometallic compounds of Si, Ge and Sn, studied long ago, both manifest themselves in the Raman spectra qualitatively in a similar way to p-p conjugation in polyenes and lead to a significant increase in intensity of the lines, corresponding to stretching vibrations of the conjugated bonds, the effect being strongly dependent on mutual orientation of the latter. It was found that pre-resonant enhancement of some lines in the Raman spectra of polymetallanes is exhibited only by macromolecules having a planar zig-zag all-anti conformation of the backbone. Less ordered conformations do not show this effect, in spite of the proximity of the position of their lowest energy electronic absorption band n e to the exciting line n. Thus, proximity of n e to n in the resonance denominator is shown to be necessary but not sufficient for the pre-resonant increase in Raman intensity to occur. These experimental findings are in good accord with Shorygin's general views on the conjugation phenomenon and with his semi-classical treatment of the Raman intensity problem, confirming an important role of the derivative @n e /@Q i that reflects the specificity of molecular electronic structure.

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Polysilanes

Oka

2002

Encyclopedia of Polymer Science and Technology

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Polysilanes have σ‐conjugated backbones and organic side groups. The energy state of polysilane is influenced by molecular weight, conformation of the backbone, side groups, and branching points. Sigma‐conjugated polysilanes show strong absorption and efficient emission in the UV region. These properties are sensitive to external stimuli and show interesting thermochromism, piezochromism, electrochromism, and solvatochromism. Undoped polysilanes are insulators but they become conductive on doping. Polysilanes are also photoconductors showing high hole drift mobility. Polysilanes are thus studied as resist materials for photo or X‐ray lithography and as emissive or hole transport materials of LEDs. The siloxane part after photolysis is used for color filter production, recording material, printing material, and production of microlens. Polysilanes are synthesized by five methods: Wurtz coupling, dehydro‐coupling, ring‐opening polymerization, anionic polymerization of masked disilene, and redistribution polymerization of alkoxylated disilanes. Functional polysilanes are prepared from SiH, SiCl, and chloromethylphenyl groups. Block copolymers with carbon blocks are prepared by photolysis of polysilanes in carbon monomers, reaction of SiCl end with living carbon polymers, atom‐transfer polymerization with carbon monomers, and polymerization of carbon monomers with living polymer from masked disilene.

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A Detailed UV and Raman Study of Poly(n-butyl-n-hexylsilylene) Phase Transitions

Cited by 36 publications

References 17 publications

Regularities and Peculiarities of Solid Polydialkylsilane Order-Disorder Transitions as Studied by Optical (UV, Raman and IR) Spectroscopy

Regularities and Peculiarities of Solid Polydialkylsilane Order-Disorder Transitions as Studied by Optical (UV, Raman and IR) Spectroscopy

Raman intensity and conjugation with participation of ordinary σ‐bonds

Polysilanes

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