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A Novel Method of Extraction of Blend Component Structure from SANS Measurements of Homopolymer Bimodal Blends.

Smerdova O, Graham RS, Gasser U, Hutchings LR, De Focatiis DS - Macromol Chem Phys (2014)

Bottom Line: The method requires a minimum of three blends, made up of hydrogenated and deuterated components with matched degree of polymerization at two different chain lengths, but with carefully varying deuteration levels.By fitting Debye functions to the structure factors, it is shown that there is good agreement between the molar mass of the components obtained from SANS and from chromatography.The extraction method also enables, for the first time, interchain scattering functions to be produced for scattering between chains of different lengths. [Formula: see text].

View Article: PubMed Central - PubMed

Affiliation: Division of Materials, Mechanics and Structures, University of Nottingham Nottingham, NG7 2RD, UK.

ABSTRACT

A new method is presented for the extraction of single-chain form factors and interchain interference functions from a range of small-angle neutron scattering (SANS) experiments on bimodal homopolymer blends. The method requires a minimum of three blends, made up of hydrogenated and deuterated components with matched degree of polymerization at two different chain lengths, but with carefully varying deuteration levels. The method is validated through an experimental study on polystyrene homopolymer bimodal blends with [Formula: see text]. By fitting Debye functions to the structure factors, it is shown that there is good agreement between the molar mass of the components obtained from SANS and from chromatography. The extraction method also enables, for the first time, interchain scattering functions to be produced for scattering between chains of different lengths. [Formula: see text].

No MeSH data available.


Normalized structure form factors ,  of low- and high-molecular-weight components within the same blend. Data extracted from SANS using the least squares technique is shown as symbols. Debye functions are fitted to these measurements and shown as lines.
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fig02: Normalized structure form factors , of low- and high-molecular-weight components within the same blend. Data extracted from SANS using the least squares technique is shown as symbols. Debye functions are fitted to these measurements and shown as lines.

Mentions: For ideal Gaussian chains of monodisperse polymers, the structure form factor is usually modeled using functions of the form:4(19)where C1 and C2 are constants, and the term in square brackets is a Debye function26 in which Rg is the radius of gyration of a polymer chain. The approach applied here is to treat the three parameters C1, C2, and Rg as fitting coefficients to obtain P(q). The resulting functions, as well as the experimentally measured form factors , extracted by the method described above for isotropic materials, are presented in Figure 2, and values of the fitting coefficients and errors calculated by the bootstrap method are reported in Table3.


A Novel Method of Extraction of Blend Component Structure from SANS Measurements of Homopolymer Bimodal Blends.

Smerdova O, Graham RS, Gasser U, Hutchings LR, De Focatiis DS - Macromol Chem Phys (2014)

Normalized structure form factors ,  of low- and high-molecular-weight components within the same blend. Data extracted from SANS using the least squares technique is shown as symbols. Debye functions are fitted to these measurements and shown as lines.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4384978&req=5

fig02: Normalized structure form factors , of low- and high-molecular-weight components within the same blend. Data extracted from SANS using the least squares technique is shown as symbols. Debye functions are fitted to these measurements and shown as lines.
Mentions: For ideal Gaussian chains of monodisperse polymers, the structure form factor is usually modeled using functions of the form:4(19)where C1 and C2 are constants, and the term in square brackets is a Debye function26 in which Rg is the radius of gyration of a polymer chain. The approach applied here is to treat the three parameters C1, C2, and Rg as fitting coefficients to obtain P(q). The resulting functions, as well as the experimentally measured form factors , extracted by the method described above for isotropic materials, are presented in Figure 2, and values of the fitting coefficients and errors calculated by the bootstrap method are reported in Table3.

Bottom Line: The method requires a minimum of three blends, made up of hydrogenated and deuterated components with matched degree of polymerization at two different chain lengths, but with carefully varying deuteration levels.By fitting Debye functions to the structure factors, it is shown that there is good agreement between the molar mass of the components obtained from SANS and from chromatography.The extraction method also enables, for the first time, interchain scattering functions to be produced for scattering between chains of different lengths. [Formula: see text].

View Article: PubMed Central - PubMed

Affiliation: Division of Materials, Mechanics and Structures, University of Nottingham Nottingham, NG7 2RD, UK.

ABSTRACT

A new method is presented for the extraction of single-chain form factors and interchain interference functions from a range of small-angle neutron scattering (SANS) experiments on bimodal homopolymer blends. The method requires a minimum of three blends, made up of hydrogenated and deuterated components with matched degree of polymerization at two different chain lengths, but with carefully varying deuteration levels. The method is validated through an experimental study on polystyrene homopolymer bimodal blends with [Formula: see text]. By fitting Debye functions to the structure factors, it is shown that there is good agreement between the molar mass of the components obtained from SANS and from chromatography. The extraction method also enables, for the first time, interchain scattering functions to be produced for scattering between chains of different lengths. [Formula: see text].

No MeSH data available.