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Macromolecules
Volumn 43, Issue 1, 2010, Pages 532-537
Dimensional description of cyclic macromolecules
Author keywords

[No Author keywords available]
Indexed keywords

BIOLOGICALLY RELEVANT MOLECULES; CYCLIC POLYMER; CYCLIC STRUCTURES; DIMENSIONAL ANALYSIS; END EFFECTS; EXPERIMENTAL DATA; FORM FACTORS; FRACTAL STRUCTURES; HIGH MOLECULAR WEIGHT; LINEAR CHAIN; LINEAR POLYMERS; LONG CHAIN MOLECULES; NEW APPROACHES; RING POLYMERS; SCALING MODEL; SCATTERING DATA;
EID: 73649142364     PISSN: 00249297     EISSN: None     Source Type: Journal    
DOI: 10.1021/ma901288k     Document Type: Article
Times cited : (39)
References (41)
  • 9
    • 0037144613 scopus 로고    scopus 로고
    • McLeish, T. Science 2002, 297, 2005-2006.
    • (2002) Science , vol.297 , pp. 2005-2006
    • McLeish, T.1
  • 32
    • 73649084510 scopus 로고    scopus 로고
    • The appropriateness of the athermal simplification can be assessed by considering the change in I(0) due to excluding the interaction parameter for linear 15 kg/mol PDMS in a H/D mixture of 50% fraction which is about 4.5% from the values given by Beaucage et al.33 This effect diminishes with increase in scattering vector and with reduction in the molecular weight. The absolute intensity measurement is generally good to about 10, For the samples listed in Tables 1 and 2, the impact of the athermal assumption is not particularly significant. The interaction parameter should be considered for higher molecular weight blends, for example for 75 kg/mol blends I(0) changes by 33%.33 In order to include the interaction pararamter the Unified function could be included as the structure factor in the RPA equation for example
    • 33 In order to include the interaction pararamter the Unified function could be included as the structure factor in the RPA equation for example.
  • 34
    • 73649144599 scopus 로고    scopus 로고
    • A single Rg value has been reported in Table 1 from the fits and because the model assumes that the H and D components have the same radius of gyration. However, some of the H/D mixtures in Table 1 are asymmetric. The model can be extended to account for polydispersity through the use of an additional parameter as proposed by Sorensen and Wang, Cp. 35 Cp for Gaussian chains is equivalent to the ratio of MzMw as described by Ramachandran et al. 25 The molecular weights for PDMS 3 in Table 1 are particularly asymmetric. For this blend we can calculate MZMw, considering monodisperse components, as 1.03 while MwMn, 1.17, This worst case value will shift d min from 1.51 to 1.47, and z from 10.5 to 9.9 while c is unchanged and ΦBr changes from 0.51 to 0.50. Hence, the scaling model is fairly insensitiv
    • Br changes from 0.51 to 0.50. Hence, the scaling model is fairly insensitive to polydispersity in the range of molecular weights studied here.
  • 41
    • 73649091174 scopus 로고    scopus 로고
    • Scattering from the lattice structure will lead to a finite I(0) value just as light scattering from nanoscale molecules leads to a finite I(0) at qRg « 1. In light scattering this constant intensity is used to calculate the weight average molecular weight from a static light scattering measurement. The I(0) associated with lattice scattering in Figure 5a leads to an excess intensity of about 0.22 that should be subtracted to obtain a reasonable power-law regime for the coil scattering. Here, 0.22 was determined by inspection of the corrected scattering curve compared to the expected power-law dependence of arbitrary slope, df in Figure 5a. This inherent background is also important in experimental determination of the structure factor at high-q and can be experimentally quantified through high-q measurements in the diffraction regime
    • g « 1. In light scattering this constant intensity is used to calculate the weight average molecular weight from a static light scattering measurement. The I(0) associated with lattice scattering in Figure 5a leads to an excess intensity of about 0.22 that should be subtracted to obtain a reasonable power-law regime for the coil scattering. Here, 0.22 was determined by inspection of the corrected scattering curve compared to the expected power-law dependence of arbitrary slope - df in Figure 5a. This inherent "background" is also important in experimental determination of the structure factor at high-q and can be experimentally quantified through high-q measurements in the diffraction regime.

* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.