Systematic Molecular Control of Interfacial Structure in Nanoporous Carbons

2003 ◽  
Vol 788 ◽  
Author(s):  
Kengqing Jian ◽  
Gregory P. Crawford ◽  
Robert H. Hurt
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Substrate Material ◽  
Interfacial Structure ◽  
Mesoporous Carbons ◽  
Nanoporous Carbons ◽  
Molecular Control ◽  
Flat Substrate ◽  
Internal Surfaces ◽  
Template Selection

ABSTRACTThe present paper describes a new concept of synthesizing nanoporous carbons that allows control not only of the pore structure, but also of the molecular structure of the internal surfaces. Interfacial molecular control is achieved through the use of discotic liquid crystalline precursors whose molecular orientation on the substrate material is known or can be determined by simple measurements on flat substrate test samples. Here a suite of nanoporous (mesoporous) carbons are synthesized from various porous glass and silica gel templates, and a model is developed to predict the carbon properties from template properties thus allowing systematic template selection.

Observing the relaxation of molecular orientation in sheared liquid crystalline polymer solutions

1990 ◽  
Vol 48 (4) ◽  
pp. 1092-1093
Author(s):  
Wendy Putnam ◽  
Christopher Viney
Keyword(s):  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Polymer Processing ◽  
Molecular Alignment ◽  
Global Alignment ◽  
Shear Direction ◽  
Axial Strength ◽  
Strength And Stiffness

Liquid crystalline polymers (solutions or melts) can be spun into fibers and films that have a higher axial strength and stiffness than conventionally processed polymers. These superior properties are due to the spontaneous molecular extension and alignment that is characteristic of liquid crystalline phases. Much of the effort in processing conventional polymers goes into extending and aligning the chains, while, in liquid crystalline polymer processing, the primary microstructural rearrangement involves converting local molecular alignment into global molecular alignment. Unfortunately, the global alignment introduced by processing relaxes quickly upon cessation of shear, and the molecular orientation develops a periodic misalignment relative to the shear direction. The axial strength and stiffness are reduced by this relaxation.Clearly there is a need to solidify the liquid crystalline state (i.e. remove heat or solvent) before significant relaxation occurs. Several researchers have observed this relaxation, mainly in solutions of hydroxypropyl cellulose (HPC) because they are lyotropic under ambient conditions.

MOLECULAR ORIENTATION AND ELECTROHYDRODYNAMIC FLOW IN HOMOGENEOUS ER FLUIDS

2001 ◽  
Vol 15 (06n07) ◽  
pp. 973-979 ◽  
Author(s):  
HIROKI IWATSUKI ◽  
NAOTO GOHKO ◽  
HIROSHI KIMURA ◽  
YUICHI MASUBUCHI ◽  
JUN-ICHI TAKIMOTO ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Electric Field ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Polypropylene Glycol ◽  
Homogeneous Fluid ◽  
Immiscible Liquids ◽  
Electrohydrodynamic Flow ◽  
Er Fluids ◽  
Er Fluid

Homogeneous ER fluid is an ER fluid which consists of a homogeneous fluid only; it is neither a suspension nor a blend of immiscible liquids. Various liquid crystals are typical examples of homogeneous ER fluids. Recently, we have found that urethane-modified polypropylene glycol (UPPG) is one of the very few examples of homogeneous ER fluids which show no liquid crystalline order. In order to clarify the mechanism of the ER effect in this fluid, we have studied, in this paper, electrohydrodynamic flow under shear and electric field.

scholarly journals Ultrafast isomerization-induced cooperative motions to higher molecular orientation in smectic liquid-crystalline azobenzene molecules

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Masaki Hada ◽  
Daisuke Yamaguchi ◽  
Tadahiko Ishikawa ◽  
Takayoshi Sawa ◽  
Kenji Tsuruta ◽  
...  
Keyword(s):  
Molecular Orientation ◽  
Soft Matter ◽  
Liquid Crystalline ◽  
Laser Polarization ◽  
Time Resolved ◽  
Cooperative Motion ◽  
Subsequent Response ◽  
Molecular Dynamics Calculations ◽  
Polarization Axis ◽  
Linearly Polarized

Abstract The photoisomerization of molecules is widely used to control the structure of soft matter in both natural and synthetic systems. However, the structural dynamics of the molecules during isomerization and their subsequent response are difficult to elucidate due to their complex and ultrafast nature. Herein, we describe the ultrafast formation of higher-orientation of liquid-crystalline (LC) azobenzene molecules via linearly polarized ultraviolet light (UV) using ultrafast time-resolved electron diffraction. The ultrafast orientation is caused by the trans-to-cis isomerization of the azobenzene molecules. Our observations are consistent with simplified molecular dynamics calculations that revealed that the molecules are aligned with the laser polarization axis by their cooperative motion after photoisomerization. This insight advances the fundamental chemistry of photoresponsive molecules in soft matter as well as their ultrafast photomechanical applications.

Specific counter-cation effect on the molecular orientation of thiocyanate anions at the aqueous solution interface

2020 ◽  
Vol 22 (18) ◽  
pp. 10106-10115
Author(s):  
Hongxing Hao ◽  
Qing Xie ◽  
Jingwen Ai ◽  
Yuan Wang ◽  
Hongtao Bian
Keyword(s):  
Aqueous Solution ◽  
Atmospheric Aerosols ◽  
Molecular Orientation ◽  
Aqueous Electrolyte ◽  
Electrolyte Solutions ◽  
Interfacial Structure ◽  
Cation Effect ◽  
Solution Interface ◽  
Wide Range ◽  
Counter Cation

Understanding the interfacial structure of aqueous electrolyte solutions is important and relevant to a wide range of systems, ranging from atmospheric aerosols to electrochemistry, and biological environments.

correlations of mechanical properties and microstructural parameters in annealed drawn film of liquid crystalline polymer in situ reinforced PP

e-Polymers ◽  
2011 ◽  
Vol 11 (1) ◽  
Author(s):  
Sayant Saengsuwan
Keyword(s):  
Mechanical Properties ◽  
Annealing Time ◽  
Crystalline Phase ◽  
Molecular Orientation ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Relative Level ◽  
Microstructural Parameters

AbstractDrawn composite thin film based on thermotropic liquid crystalline polymer (TLCP) and polypropylene (PP) was annealed at 130 °C at different times. The influence of annealing time on microstructural and mechanical properties of the composite film has been studied. The correlation in mechanical properties and their microstructural parameters has also been investigated. X-Ray diffraction results reveal that the smectic mesophase transforms progressively into the monoclinic phase as annealing time is increased. Consequently, the true crystallinity (Xc), crystal thickness (L) as well as relative level of molecular orientation of PP crystalline phase in the annealed TLCP/PP films are increased significantly. Also, the TLCP fibrils have no influence on the microstructure of PP crystalline phase. The apparent crystallinity (Xc,a) of PP phase evaluated by DSC also increase significantly with annealing time. As a result, the increases of these microstructural parameters coupled with the reinforcement of TLCP fibrils could be contributed directly to the remarkable enhancement of mechanical properties of the annealed TLCP/PP film in both machine (MD) and transverse (TD) directions. The correlation of moduli with microstructural parameters (Xc, Xc,a and L) exhibits nonlinear relations. However, the relative level of molecular orientation is a more suitable parameter to correlate with the improvement of mechanical properties of the annealed TLCP/PP film. Finally, this work presents that the mechanical properties of the TLCP in situ reinforced thermoplastics can be significantly enhanced via a simple thermal treatment.

Lyotropic Liquid Crystalline Mesophase Governs Interfacial Molecular Orientation of Conjugated Polymer Thin Films

2020 ◽  
Vol 32 (14) ◽  
pp. 6043-6054
Author(s):  
Ge Qu ◽  
Kyung Sun Park ◽  
Prapti Kafle ◽  
Fengjiao Zhang ◽  
Justin J. Kwok ◽  
...  
Keyword(s):  
Thin Films ◽  
Conjugated Polymer ◽  
Molecular Orientation ◽  
Liquid Crystalline ◽  
Polymer Thin Films

Interfacial Structure and Correlations in Finite-Sized Liquid-Crystalline Polymer Films

1995 ◽  
Vol 32 (5) ◽  
pp. 419-424 ◽  
Author(s):  
R. E Geer ◽  
A. F Thibodeaux ◽  
R. S Duran ◽  
R Shashidhar
Keyword(s):  
Polymer Films ◽  
Liquid Crystalline Polymer ◽  
Liquid Crystalline ◽  
Crystalline Polymer ◽  
Interfacial Structure
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