Molecularly Non-Homogeneous Nematic Polymers

1992 ◽  
pp. 399-410
Author(s):  
X. J. Wang ◽  
M. Warner
Keyword(s):  
Nematic Polymers

Elastic constant anisotropy and disclination interaction in nematic polymers II. Effect of disclination interaction

2003 ◽  
Vol 30 (7) ◽  
pp. 775-784 ◽  
Author(s):  
Wenhui Song ◽  
Houjie Tu ◽  
Gerhard Goldbeck-wood ◽  
Alan H Windle
Keyword(s):  
Elastic Constant ◽  
Nematic Polymers

Thermotropic Chiral Nematic Polymers as Optical Materials

1989 ◽  
Vol 175 ◽  
Author(s):  
S.H. Chen ◽  
M.L. Tsai ◽  
S.D. Jacobs
Keyword(s):  
Optical Materials ◽  
Helical Structure ◽  
Structural Features ◽  
Optically Active ◽  
Structure Property ◽  
Chiral Compound ◽  
Structure Property Relationships ◽  
Chiral Nematic ◽  
Chiral Structures ◽  
Nematic Polymers

AbstractChiral nematic copolymers based on optically active cholesterol, dihydrocholesterol, (R)-(+)- and (S)-(−)-1-phenylethylamine, and (+)- and (−)- isopinocampheol were synthesized and characterized for the investigations of thermotropic and optical properties. Although helical sense does not appear to correlate with the sign of [α]D of the precursor chiral compound as suggested by the observations of cholesteryl and dihydrocholesteryl copolymers, the inversion of chirality in the pendant group, (R)-(+)- vs (S)-(−)-1-phenylethylamine, does lead to the opposite handedness in the resultant helical structure. To better understand the structure-property relationships involving helical sense and twisting power, systematic studies of the roles played by both nematogenic and chiral structures as well as other structural features of the comonomers should be conducted.

Rod to coil transitions in nematic polymers

1985 ◽  
Vol 18 (15) ◽  
pp. 3007-3026 ◽  
Author(s):  
M Warner ◽  
J M F Gunn ◽  
A B Baumgartner
Keyword(s):  
Nematic Polymers

scholarly journals Kinetic Structure Simulations of Nematic Polymers in Plane Couette Cells. I: The Algorithm and Benchmarks

2005 ◽  
Vol 3 (4) ◽  
pp. 853-870 ◽  
Author(s):  
Ruhai Zhou ◽  
M. Gregory Forest ◽  
Qi Wang
Keyword(s):  
Nematic Polymers

Explicit Flow-Aligned Orientational Distribution Functions for Dilute Nematic Polymers in Weak Shear

2002 ◽  
Author(s):  
M. Gregory Forest ◽  
Ruhai Zhou ◽  
Qi Wang
Keyword(s):  
Kinetic Theory ◽  
Mean Field ◽  
Distribution Functions ◽  
Small Molecular Weight ◽  
Exact Probability ◽  
Exact Probability Distribution ◽  
Orientational Distribution ◽  
Alignment Angle ◽  
Nematic Polymers ◽  
Leslie Angle

Flow-alignment of sheared nematic polymers occurs in various flow-concentration regimes. Analytical descriptions of shear-aligned nematic monodomains have a long history across continuum, mesoscopic and mean-field kinetic models, sacrificing precision at each finer scale. Continuum Leslie-Ericksen theory applies to highly concentrated, weak flows of small molecular weight polymers, giving an explicit macroscopic alignment angle formula dependent only on Miesowicz viscosities. Mesoscopic tensor models apply at all concentrations and shear rates, but explicit “Leslie angle” formulas exist only in the weak shear limit (Cocchini et. al, 90; Bhave et. al, 93; Wang, 97; Rienacker and Hess, 99; Maffettone et. al, 00; Forest and Wang, 02; Forest et. al, 02c; Grecov and Rey, 02), with distinct behavior in dilute versus concentrated regimes. Exact probability distribution functions (pdf’s) of kinetic theory do not exist for highly concentrated nematic states, even without flow, although appealing flow-aligned approximations have been derived (Kuzuu and Doi, 83; Kuzuu and Doi, 84; Semenov, 83; Semenov, 86; Archer and Larson, 95; Kroger and Seller, 95), which offer a molecular theory basis for the Leslie alignment angle. A simpler problem concerns the dilute concentration regime where the unique quiescent equilibrium is isotropic, corresponding to a constant pdf, and whose weak shear deformation is robust to mesoscopic closure approximation (Forest and Wang, 02; Forest et. al, 02c): steady, flow-aligning, weakly anisotropic, and biaxial. The purpose of this paper is to explicitly construct the weakly anisotropic branch of stationary pdf’s by a weak-shear asymptotic expansion of kinetic theory. A second-moment pdf projection confirms mesoscopic model predictions, and further yields explicit Leslie angle and degree of alignment formulas in terms of molecular parameters and normalized shear rate.

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