Comparative Dielectric Studies of Segmental and Normal Mode Dynamics of Poly(oxybutylene) and Poly(oxyethylene)−Poly(oxybutylene) Diblock Copolymers

2000 ◽  
Vol 33 (12) ◽  
pp. 4581-4595 ◽  
Author(s):  
Apostolos Kyritsis ◽  
Polycarpos Pissis ◽  
Shao-Min Mai ◽  
Colin Booth
Keyword(s):  
Normal Mode ◽  
Diblock Copolymers ◽  
Dielectric Studies

Composition Fluctuation Effects on Dielectric Normal-Mode Relaxation in Diblock Copolymers. 1. Weak Segregation Regime

1994 ◽  
Vol 27 (13) ◽  
pp. 3543-3552 ◽  
Author(s):  
K. Karatasos ◽  
S. H. Anastasiadis ◽  
A. N. Semenov ◽  
G. Fytas ◽  
M. Pitsikalis ◽  
...  
Keyword(s):  
Normal Mode ◽  
Diblock Copolymers ◽  
Composition Fluctuation ◽  
Fluctuation Effects

Composition Fluctuation Effects on Dielectric Normal-Mode Relaxation in Diblock Copolymers. 2. Disordered State in Proximity to the ODT and Ordered State

1996 ◽  
Vol 29 (4) ◽  
pp. 1326-1336 ◽  
Author(s):  
K. Karatasos ◽  
S. H. Anastasiadis ◽  
G. Floudas ◽  
G. Fytas ◽  
S. Pispas ◽  
...  
Keyword(s):  
Normal Mode ◽  
Diblock Copolymers ◽  
Composition Fluctuation ◽  
Fluctuation Effects ◽  
Ordered State

Morphological behavior of compatibilized ternary blends prepared by mechanical mixing

1993 ◽  
Vol 51 ◽  
pp. 1200-1201
Author(s):  
S.D. Smith ◽  
R.J. Spontak ◽  
D.H. Melik ◽  
S.M. Buehler ◽  
K.M. Kerr ◽  
...  
Keyword(s):  
Interfacial Adhesion ◽  
Diblock Copolymers ◽  
Ternary Blends ◽  
Mechanical Mixing ◽  
Design Considerations ◽  
Covalently Bonded ◽  
Homopolymer Blends ◽  
Emulsifying Agent ◽  
Surface Active ◽  
Low Entropy

When blended together, homopolymers A and B will normally macrophase-separate into relatively large (≫1 μm) A-rich and B-rich phases, between which exists poor interfacial adhesion, due to a low entropy of mixing. The size scale of phase separation in such a blend can be reduced, and the extent of interfacial A-B contact and entanglement enhanced, via addition of an emulsifying agent such as an AB diblock copolymer. Diblock copolymers consist of a long sequence of A monomers covalently bonded to a long sequence of B monomers. These materials are surface-active and decrease interfacial tension between immiscible phases much in the same way as do small-molecule surfactants. Previous studies have clearly demonstrated the utility of block copolymers in compatibilizing homopolymer blends and enhancing blend properties such as fracture toughness. It is now recognized that optimization of emulsified ternary blends relies upon design considerations such as sufficient block penetration into a macrophase (to avoid block slip) and prevention of a copolymer multilayer at the A-B interface (to avoid intralayer failure).

Triply-periodic nanostructures in surfactant, block copolymer, and biomembrane systems, and simulation of TEMs

1993 ◽  
Vol 51 ◽  
pp. 884-885
Author(s):  
David M. Anderson ◽  
Tomas Landh
Keyword(s):  
Liquid Crystalline ◽  
Diblock Copolymers ◽  
Cubic Phase ◽  
List Type ◽  
Interpenetrating Networks ◽  
Triply Periodic ◽  
Wide Range ◽  
Bicontinuous Cubic ◽  
Phase Liquid ◽  
Dividing Surface

First discovered in surfactant-water liquid crystalline systems, so-called ‘bicontinuous cubic phases’ have the property that hydropnilic and lipophilic microdomains form interpenetrating networks conforming to cubic lattices on the scale of nanometers. Later these same structures were found in star diblock copolymers, where the simultaneous continuity of elastomeric and glassy domains gives rise to unique physical properties. Today it is well-established that the symmetry and topology of such a morphology are accurately described by one of several triply-periodic minimal surfaces, and that the interface between hydrophilic and hydrophobic, or immiscible polymer, domains is described by a triply-periodic surface of constant, nonzero mean curvature. One example of such a dividing surface is shown in figure 5.The study of these structures has become of increasing importance in the past five years for two reasons:1)Bicontinuous cubic phase liquid crystals are now being polymerized to create microporous materials with monodispersed pores and readily functionalizable porewalls; figure 3 shows a TEM from a polymerized surfactant / methylmethacrylate / water cubic phase; and2)Compelling evidence has been found that these same morphologies describe biomembrane systems in a wide range of cells.

Equilibrium emulsification of polymer blends by diblock copolymers

1990 ◽  
Vol 51 (2) ◽  
pp. 185-200 ◽  
Author(s):  
Zhen-Gang Wang ◽  
S.A. Safran
Keyword(s):  
Polymer Blends ◽  
Diblock Copolymers

The Nusayris in Medieval Syria

2018 ◽  
Author(s):  
Stefan Winter
Keyword(s):  
Normal Mode ◽  
Early Development ◽  
A Priori ◽  
Medieval Period ◽  
Historical Sources

This chapter re-examines the early development of the ʻAlawi community and its situation in western Syria in the medieval period in the wider context of what might be termed Islamic provincial history. It starts from the premise that the conventional image of the “Nusayris” has largely been fashioned by elite historical sources whose discourse on nonorthodox groups is a priori negative but which, when read against the grain and compared with other sources, can yield a less essentializing, less conflicting account of the community's development. In particular, the chapter aims to show that the ʻAlawi faith was not the deviant, marginal phenomenon it has retrospectively been made out to be but, on the contrary, constituted, and was treated by the contemporary authorities as, a normal mode of rural religiosity in Syria.

Mechanical and Structural Consequences of Associative Dynamic Cross-Linking in Acrylic Diblock Copolymers

2019 ◽  
Author(s):  
Jacob Ishibashi ◽  
Yan Fang ◽  
Julia Kalow
Keyword(s):  
Block Copolymers ◽  
Rheological Properties ◽  
Diblock Copolymers ◽  
Cross Linking ◽  
Statistical Copolymer

<p>Block copolymers are used to construct covalent adaptable networks that employ associative exchange chemistry (vitrimers). The resulting vitrimers display markedly different nanostructural, thermal and rheological properties relative to those of their statistical copolymer-derived counterparts. This study demonstrates that prepolymer sequence is a versatile strategy to modify the properties of vitrimers.</p>

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