Orientation of macromolecules and elastic deformations in polymer melts. Influence of molecular structure on the reptation of molecules

Author(s):  
H. M. Laun
2018 ◽  
Vol 51 (12) ◽  
pp. 4670-4677 ◽  
Author(s):  
Sohdam Jeong ◽  
Soowon Cho ◽  
Jun Mo Kim ◽  
Chunggi Baig

2016 ◽  
Vol 2 (11) ◽  
pp. e1601478 ◽  
Author(s):  
Jarosław Paturej ◽  
Sergei S. Sheiko ◽  
Sergey Panyukov ◽  
Michael Rubinstein

Bottlebrushes are fascinating macromolecules that display an intriguing combination of molecular and particulate features having vital implications in both living and synthetic systems, such as cartilage and ultrasoft elastomers. However, the progress in practical applications is impeded by the lack of knowledge about the hierarchic organization of both individual bottlebrushes and their assemblies. We delineate fundamental correlations between molecular architecture, mesoscopic conformation, and macroscopic properties of polymer melts. Numerical simulations corroborate theoretical predictions for the effect of grafting density and side-chain length on the dimensions and rigidity of bottlebrushes, which effectively behave as a melt of flexible filaments. These findings provide quantitative guidelines for the design of novel materials that allow architectural tuning of their properties in a broad range without changing chemical composition.


1990 ◽  
Vol 26 (6) ◽  
pp. 667-673 ◽  
Author(s):  
L.A. Hanna ◽  
P.J. Hendra ◽  
D.A. Hodgson ◽  
G. Ellis ◽  
M.A. Taylor ◽  
...  

Author(s):  
Wah Chiu ◽  
David Grano

The periodic structure external to the outer membrane of Spirillum serpens VHA has been isolated by similar procedures to those used by Buckmire and Murray (1). From SDS gel electrophoresis, we have found that the isolated fragments contain several protein components, and that the crystalline structure is composed of a glycoprotein component with a molecular weight of ∽ 140,000 daltons (2). Under an electron microscopic examination, we have visualized the hexagonally-packed glycoprotein subunits, as well as the bilayer profile of the outer membrane. In this paper, we will discuss some structural aspects of the crystalline glycoproteins, based on computer-reconstructed images of the external cell wall fragments.The specimens were prepared for electron microscopy in two ways: negatively stained with 1% PTA, and maintained in a frozen-hydrated state (3). The micrographs were taken with a JEM-100B electron microscope with a field emission gun. The minimum exposure technique was essential for imaging the frozen- hydrated specimens.


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