Crystalline structure of poly(methyl-n-propylsilane)

Jambe, Baudouin; Jonas, Alain M.; Devaux, Jacques

doi:10.1002/(sici)1099-0488(19970730)35:10<1533::aid-polb6>3.0.co;2-s

Cited by 20 publications

(17 citation statements)

References 9 publications

(11 reference statements)

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“…Example "high" and "low" temperature (with respect to the thermochromic transitions) diffraction and UV absorption spectra for pMePrSi, pMeBuSi, and pMe-HexSi are shown in Figure 1, and where available, these data agree with prior reports. [23][24][25]34,35 PMePrSi clearly undergoes a thermochromic transition, near 45 °C, with improved σ conjugation in the ordered state and a bathochromic shift. The X-ray data also span this order-disorder transition with sharper peaks, indicative of a partial crystallization, forming at temperatures below 45 °C.…”

Section: General Results and Discussion Of Poly(methyl-n-propyl)silanementioning

confidence: 99%

“…Although atactic, poly(methyl-n-propylsilane), pMePrSi, exhibits a significant fraction of partially crystalline material which, when pulled into a fibers, contains a relatively high degree of chain orientation. 22 Analysis of this crystalline fraction is universally claimed to be consistent with a nearly planar chain conformation [22][23][24] although no corresponding references to the UV absorption properties are made. A UV absorption study of various longer poly(methyl-n-alkylsilane)s, by Yuan and West, 25 is indicative of less planar conformations (λ max < 350 nm).…”

Section: Introductionmentioning

confidence: 99%

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Structure and Chain Conformation in Poly(methyl-n-alkyl)silanes

Chunwachirasiri¹,

Kanaglekar²,

Winokur³

et al. 2001

Macromolecules

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Three asymmetrically substituted methyl-alkyl-substituted polysilanes, poly(methyl-npropyl)silane, poly(methyl-n-butyl)silane, and poly(methyl-n-hexyl)silane, have been studied using conventional X-ray ray diffraction and direct measurements of the local structure (through a pair correlation function analysis) in combination with UV absorption spectroscopy. These data universally support Si backbone models which are dominated by the presence of mixed transoid (T), deviant (D), and, possibly, ortho (O) conformations with dihedral angles approximating (170°, (155°, and (90°, respectively. There is no evidence for a significant fraction of all-anti (A, i.e., trans-planar), all-transoid, or anti-gauche conformers. Crystalline poly(methyl-n-hexyl)silane incorporates a D/T-based Si backbone, and this, locally, approximates a D+T+D-T-motif. Poly(methyl-n-hexyl)silane displays a number of low-temperature polymorphic structures, and one of these is found to exhibit Bragg-like scattering features. Temperature-dependent UV absorption measurements of poly(methyl-n-hexyl)silane resolve two distinguishable isosbestic points and are indicative of mesomorphic behavior.

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Section: General Results and Discussion Of Poly(methyl-n-propyl)silanementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Structure and Chain Conformation in Poly(methyl-n-alkyl)silanes

Chunwachirasiri¹,

Kanaglekar²,

Winokur³

et al. 2001

Macromolecules

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“…As shown in the inset of Figure 7, the surface area decreases abruptly in the range from 30 to 45 °C. Because the melting point (T m ) of PMPrS in the bulk state is 43.8 °C, 28 it can be said that the abrupt change in the surface area implies T m of the monolayers. Domains of the PMPrS-g-MAH monolayer coalesce with one another, and the defects among them decrease because PMPrS main chains melt and become fluid above T m .…”

Section: ' Results and Discussionmentioning

confidence: 99%

Orientation of Radiation-Modified Polysilane in Monolayers at the Air/Water Interface As Revealed from Its Optical Property

et al. 2011

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“…We consider that this difference is attributed to the dissimilar structure of these two monolayers at the air/water interface due to the disparity in the length and density of the grafted chains. PMPrS (1.14 g/cm 3 ) and MAH (1.48 g/cm 3 ) in the bulk state [26,27], respectively, w Si and w MAH are the weight fractions of PMPrS graft chains and MAH graft units, respectively, and A is the occupied surface area of a PMPrS-g-MAH monolayer. The result of the calculation is listed in Table 2.…”

Section: Monolayers Of Pmprs-g-mahmentioning

confidence: 99%

Effect of the graft chain length and density on the morphology of radiation-modified polysilane monolayers at the air/water interface

Tanaka

Kunai

Sato

et al. 2011

Journal of Colloid and Interface Science

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The variation in the morphology of monolayers at the air/water interface is investigated for two kinds of radiation-modified polysilanes with different structures: poly(diethyl fumarate)-grafted poly(methyl-n-propylsilane) (PMPrS-g-PDEF) and maleic anhydride-grafted PMPrS (PMPrS-g-MAH). PMPrS-g-PDEF has long but sparsely-attached PDEF graft chains, while PMPrS-g-MAH has short but densely-attached MAH graft units. Surface pressure-area measurements indicate that PMPrS-g-PDEF monolayers extensively spread at the air/water interface though PMPrS homopolymer hardly spreads. AFM observation reveals that PMPrS-g-PDEF monolayers have an inhomogeneous structure containing string-like microstructures. This result suggests that PMPrS main chains are detached from the water surface to aggregate together and only PDEF chains spread over the water surface. In contrast, PMPrS-g-MAH forms uniform monolayers with a smooth surface. PMPrS main chains of PMPrS-g-MAH are anchored to the water surface by densely grafted MAH units. It is also demonstrated that only the PMPrS-g-MAH monolayers are successfully deposited layer-by-layer on a solid substrate by the Y-type deposition.

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Crystalline structure of poly(methyl-n-propylsilane)

Cited by 20 publications

References 9 publications

Structure and Chain Conformation in Poly(methyl-n-alkyl)silanes

Structure and Chain Conformation in Poly(methyl-n-alkyl)silanes

Orientation of Radiation-Modified Polysilane in Monolayers at the Air/Water Interface As Revealed from Its Optical Property

Effect of the graft chain length and density on the morphology of radiation-modified polysilane monolayers at the air/water interface

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