Small Angle Neutron Scattering and Time Resolved Small Angle X-Ray Scattering Studies of Triblock Copolymers in Extension

1986 ◽  
Vol 79 ◽  
Author(s):  
R. W. Richards ◽  
J. T. Mullin
Keyword(s):  
Solid State ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Triblock Copolymers ◽  
Cylindrical Domain ◽  
Long Range Order ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Order Domain

Linear triblock copolymers of styrene and isoprene with isoprene as the centre block are microphase separated elastomers in the solid state. The styrene blocks form domains of regular morphology 1arranged on a paracrystalline lattice with considerable long range order. Domain symmetry is chiefly determined by the composition of the block copolymer; only cylindrical domain geometry is dealt with here. Three levels of organisation can be recognised.

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

scholarly journals Osmotic shrinkage of sterically stabilized liposomes as revealed by time-resolved small-angle X-ray scattering

2014 ◽  
Vol 47 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Zoltán Varga ◽  
András Wacha ◽  
Attila Bóta
Keyword(s):  
Form Factor ◽  
Small Angle ◽  
Freeze Fracture ◽  
Initial Step ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Sterically Stabilized Liposomes ◽  
Liposome Size ◽  
Ray Scattering

Time-resolved synchrotron small-angle X-ray scattering (SAXS) was used to study the structural changes during the osmotic shrinkage of a pharmacologically relevant liposomal drug delivery system. Sterically stabilized liposomes (SSLs) with a diameter of 100 nm and composed of hydrogenated soy phosphocholine, cholesterol and distearoyl-phosphoethanolamine-PEG 2000 prepared in a salt-free buffer were mixed with a buffered 0.3 MNaCl solution using a stopped flow apparatus. The changes in the liposome size and the bilayer structure were followed by using SAXS with a time resolution of 20 ms. A linear decrease in liposome size is observed during the first ∼4 s of the osmotic shrinkage, which reveals a water permeability value of 0.215 (15) µm s−1. The change in the size of the liposomes upon the osmotic shrinkage is also confirmed by dynamic light scattering. After this initial step, broad correlation peaks appear on the SAXS curves in theqrange of the bilayer form factor, which indicates the formation of bi- or oligolamellar structures. Freeze-fracture combined with transmission electron microscopy revealed that lens-shaped liposomes are formed during the shrinkage, which account for the appearance of the quasi-Bragg peaks superimposed on the bilayer form factor. On the basis of these observations, it is proposed that the osmotic shrinkage of SSLs is a two-step process: in the initial step, the liposome shrinks in size, while the area/lipid adapts to the decreased surface area, which is then followed by the deformation of the spherical liposomes into lens-shaped vesicles.

Time-resolved isothermal crystallization of absorbable PGA-co-PLA copolymer by synchrotron small-angle X-ray scattering and wide-angle X-ray diffraction

Polymer ◽  
2001 ◽  
Vol 42 (21) ◽  
pp. 8965-8973 ◽  
Author(s):  
Zhi-Gang Wang ◽  
Xuehui Wang ◽  
Benjamin S. Hsiao ◽  
Saša Andjelić ◽  
Dennis Jamiolkowski ◽  
...  
Keyword(s):  
Small Angle ◽  
Isothermal Crystallization ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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