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Journal of the American Chemical Society
Volumn 130, Issue 1, 2008, Pages 229-236
Two- and three-dimensional smectic ordering of single-handed helical polymers
Author keywords

[No Author keywords available]
Indexed keywords

MOLECULAR WEIGHT; POLYMERIZATION; TWO DIMENSIONAL; X RAY DIFFRACTION;
EID: 38349080853     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja074627u     Document Type: Article
Times cited : (93)
References (52)
  • 36
    • 38349045916 scopus 로고    scopus 로고
    • The difference in the Mw's of poly-L-1(, and poly-L-1(, can be explained on the basis of the difference in propagation rates of the two growing species, giving high- and low-Mw polymers, respectively. Plots of the number-average molecular weight (Mn) of left-handed helical poly-L-1(, and right-handed helical poly-L-1(, versus feed molar ratio of the monomer L-1 to the initiator (2, L-1/[2, gave an almost linear correlation Figure S10, which is indicative of a mechanism in which diastereomeric oligomers of L-1 with both helical senses are formed during the initial stage of polymerization and one of the two appears to propagate rapidly over the other, producing right- and left-handed helical poly-L-1's with different Mw's. The reason why diastereomeric oligomers with both hel
    • 8
  • 38
    • 38349066051 scopus 로고    scopus 로고
    • 3, respectively, which are in good agreement with the observed values. When the number of repeating units per fiber period is assumed to be other than 15, the calculated densities were considerably different from the observed densities. For more details, see Supporting Information.
    • 3, respectively, which are in good agreement with the observed values. When the number of repeating units per fiber period is assumed to be other than 15, the calculated densities were considerably different from the observed densities. For more details, see Supporting Information.
  • 39
    • 38349066898 scopus 로고    scopus 로고
    • This method is very useful for constructing highly ordered 2D helix-bundles for helical polyacetylenes and polyisocyanides on HOPG, and their helical structures were visualized by AFM.8,16
    • 8,16
  • 41
    • 38349023766 scopus 로고    scopus 로고
    • n) of poly-L-1(-) and poly-L-1(+) were estimated to be 13 ± 5.2 nm and 1.15 and 5.8 ± 2.2 nm and 1.14, respectively. The estimated chain lengths by AFM almost perfectly coincide with those estimated by the SEC-MALS (B and C of Figure 3).
    • n) of poly-L-1(-) and poly-L-1(+) were estimated to be 13 ± 5.2 nm and 1.15 and 5.8 ± 2.2 nm and 1.14, respectively. The estimated chain lengths by AFM almost perfectly coincide with those estimated by the SEC-MALS (B and C of Figure 3).
  • 42
    • 38348999832 scopus 로고    scopus 로고
    • In the same way, the Ln, Lw/Ln, helical sense, and helical pitch of poly-L-1200(, and poly-D-1(, can be estimated from the high-resolution AFM images Figure S5
    • 200(-) and poly-D-1(+) can be estimated from the high-resolution AFM images (Figure S5).
  • 43
    • 38349007426 scopus 로고    scopus 로고
    • We preliminarily measured high-resolution AFM images of the as-prepared poly-L-1 (a mixture of high-molecular weight poly-L-1(, and low-molecular weight poly-L-1(, ) cast from a benzene solution on HOPG. We anticipated a spontaneous diastereomeric domain formation. However, as shown in Figure S11, 2D smecticlike layered domains composed of either a right- or left-handed helical poly-L-1 could not be clearly observed. It seems likely that the molecular length may play a dominant role in such a 2D smecticlike layer formation. Apparently, a further thorough study is necessary to explore a possible spontaneous domain formation
    • We preliminarily measured high-resolution AFM images of the as-prepared poly-L-1 (a mixture of high-molecular weight poly-L-1(-) and low-molecular weight poly-L-1(+) ) cast from a benzene solution on HOPG. We anticipated a spontaneous diastereomeric domain formation. However, as shown in Figure S11, 2D smecticlike layered domains composed of either a right- or left-handed helical poly-L-1 could not be clearly observed. It seems likely that the molecular length may play a dominant role in such a 2D smecticlike layer formation. Apparently, a further thorough study is necessary to explore a possible spontaneous domain formation.
  • 49
    • 38349040914 scopus 로고    scopus 로고
    • Poly-D-1(+) was treated with CuCl in piperidine to eliminate the terminal Pd residues prior to the SR-SAXS measurements, since the smectic layer reflections could not be observed for the magnetic-oriented polymers bearing the terminal Pd residues prepared under identical conditions; the reason is not clear, but probably due to the high atomic scattering factor of the Pd metals at the polymer ends (for more details, see Experimental Section and Supporting Information).
    • Poly-D-1(+) was treated with CuCl in piperidine to eliminate the terminal Pd residues prior to the SR-SAXS measurements, since the smectic layer reflections could not be observed for the magnetic-oriented polymers bearing the terminal Pd residues prepared under identical conditions; the reason is not clear, but probably due to the high atomic scattering factor of the Pd metals at the polymer ends (for more details, see Experimental Section and Supporting Information).
  • 50
    • 38349044990 scopus 로고    scopus 로고
    • Two-dimensional smecticlike assemblies of the polymer chains with a controlled spacing were also observed in AFM images of poly-D- 1(, on HOPG Figure S7, The average layer spacing 14 nm is consistent with that determined by SR-SAXS and TEM
    • Two-dimensional smecticlike assemblies of the polymer chains with a controlled spacing were also observed in AFM images of poly-D- 1(+) on HOPG (Figure S7). The average layer spacing 14 nm is consistent with that determined by SR-SAXS and TEM.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.