Orientation Birefringence Regulation for the Binary Blend Film of Cellulose Triacetate and Rigid-Rod-Like 5CB Molecules

2021 ◽  
Author(s):  
Tong Wu ◽  
Xiaoyu Min ◽  
Xueqing Han ◽  
Minfang An ◽  
Jingyun Zhao ◽  
...  
Keyword(s):  
Cellulose Triacetate ◽  
Binary Blend ◽  
Blend Film ◽  
Rigid Rod

Ordered Morphologies on the Binary Blend of Diblock Copolymers Film Induced by Nanoparticles

NANO ◽  
2016 ◽  
Vol 11 (01) ◽  
pp. 1650008 ◽  
Author(s):  
Min-Na Sun ◽  
Jin-Jun Zhang ◽  
Jun-Xing Pan ◽  
Bao-Feng Wang ◽  
Hai-Shun Wu
Keyword(s):  
Diblock Copolymers ◽  
Chemical Potential ◽  
Control Mechanism ◽  
Oscillation Period ◽  
Binary Blend ◽  
Range Interaction ◽  
Coupling Energy ◽  
Blend Film ◽  
Copolymer Blend ◽  
Film Form

In this study, we investigate the ordered morphologies on the binary blend of diblock copolymers film induced by the mobile wettable nanoparticles on the substrate. The film forms highly ordered microphase and macrophase morphologies. We constructed the phase diagram, which suggests that the ordered-striped macrophase structures are due to the competition equilibrium of the wetting strength and the chemical potential amplitude upon the nanoparticles. The morphologies of the binary blend film form the striped pattern of different periods with the changing oscillation period of the chemical potential. The short-range interaction between monomers only alters the microphase structures. We analyzed the variation in the interfacial energy, the wetting energy and the particles/substrate’s coupling energy on different morphologies. The results provide a new control mechanism to stabilize the ordered microphase and macrophase structures within the copolymer blend film.

Morphology of High-Performance Rigid-Rod Polymer Fibers and Molecular Composites

1989 ◽  
Vol 47 ◽  
pp. 338-339
Author(s):  
W.W. Adams ◽  
S. J. Krause
Keyword(s):  
Tensile Strength ◽  
High Performance ◽  
Liquid Crystalline ◽  
Molecular Level ◽  
Synergistic Effects ◽  
Tensile Modulus ◽  
Commercial Development ◽  
The Matrix ◽  
Molecular Composites ◽  
Rigid Rod

Rigid-rod polymers such as PBO, poly(paraphenylene benzobisoxazole), Figure 1a, are now in commercial development for use as high-performance fibers and for reinforcement at the molecular level in molecular composites. Spinning of liquid crystalline polyphosphoric acid solutions of PBO, followed by washing, drying, and tension heat treatment produces fibers which have the following properties: density of 1.59 g/cm3; tensile strength of 820 kpsi; tensile modulus of 52 Mpsi; compressive strength of 50 kpsi; they are electrically insulating; they do not absorb moisture; and they are insensitive to radiation, including ultraviolet. Since the chain modulus of PBO is estimated to be 730 GPa, the high stiffness also affords the opportunity to reinforce a flexible coil polymer at the molecular level, in analogy to a chopped fiber reinforced composite. The objectives of the molecular composite concept are to eliminate the thermal expansion coefficient mismatch between the fiber and the matrix, as occurs in conventional composites, to eliminate the interface between the fiber and the matrix, and, hopefully, to obtain synergistic effects from the exceptional stiffness of the rigid-rod molecule. These expectations have been confirmed in the case of blending rigid-rod PBZT, poly(paraphenylene benzobisthiazole), Figure 1b, with stiff-chain ABPBI, poly 2,5(6) benzimidazole, Fig. 1c A film with 30% PBZT/70% ABPBI had tensile strength 190 kpsi and tensile modulus of 13 Mpsi when solution spun from a 3% methane sulfonic acid solution into a film. The modulus, as predicted by rule of mixtures, for a film with this composition and with planar isotropic orientation, should be 16 Mpsi. The experimental value is 80% of the theoretical value indicating that the concept of a molecular composite is valid.

Alignment of Rigid-Rod Polypeptide Chains by Solvent Quenching

2003 ◽  
Vol 771 ◽  
Author(s):  
Yuli Wang ◽  
Ying Chih Chang
Keyword(s):  
Tilt Angle ◽  
Rigid Rod ◽  
Polypeptide Chains ◽  
Poor Solvent

AbstractWe introduce a simple “solvent quenching” approach to align the rigid-rod à-helical poly(α-benzyl-L-glutamate) (PBLG) chains in the surface-grafted monolayer. By sequentially treating with a good solvent and a poor solvent, a unidirectionally aligned PBLG monolayer with an average tilt angle as small as 3° is obtained.

Probing the Versatility of Shape-Persistent Tetraphenylmethane Dendrimers by Modification of the Skeleton

2019 ◽  
Author(s):  
Julio Ignacio Urzúa ◽  
Sandra Campana ◽  
Massimo Lazzari ◽  
Mercedes Torneiro
Keyword(s):  
Design Principle ◽  
Focal Point ◽  
Sonogashira Coupling ◽  
Terminal Alkyne ◽  
Double Phase ◽  
Rigid Rod ◽  
Convergent Approach ◽  
First And Second Generation ◽  
Oxidative Homocoupling ◽  
Hypercrosslinked Polymers

Tetraphenylmethane has emerged as a recurrent building block for advanced porous materials such as COFs, PAFs and hypercrosslinked polymers. Guided by a similar design principle, we have previously synthesized shape-persistent dendrimers with tetraphenylmethane nodes and ethynylene linkers. Here we report the generality of our approach by describing new dendritic architectures built from tetraphenylmethane. First, we prepared expanded dendrimers where the tetrahedral units are bonded through larger rigid rod spacers. Among the different synthetic strategies tested, the convergent route, with alternating steps of Pd-catalyzed Sonogashira coupling and alkyne activation by removal of TMS masking groups, efficiently afforded the first- and second-generation dendrimers. A second type of compounds having a linear diyne at the core is also described. The dendrimers of generations 1-2 were also synthesized by a convergent approach, with the diyne being assembled in the last step of the synthesis by a Glaser oxidative homocoupling of the corresponding dendrons bearing a terminal alkyne at the focal point. A third-generation dendrimer was also successfully prepared by a double-phase strategy.<br>

scholarly journals Settling of an asymmetric dumbbell in a quiescent fluid

2016 ◽  
Vol 802 ◽  
pp. 174-185 ◽  
Author(s):  
F. Candelier ◽  
B. Mehlig
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Size Difference ◽  
Fluid Inertia ◽  
Horizontal Orientation ◽  
Vertically Aligned ◽  
Rigid Rod ◽  
Quiescent Fluid

We compute the hydrodynamic torque on a dumbbell (two spheres linked by a massless rigid rod) settling in a quiescent fluid at small but finite Reynolds number. The spheres have the same mass densities but different sizes. When the sizes are quite different, the dumbbell settles vertically, aligned with the direction of gravity, the largest sphere first. But when the size difference is sufficiently small, then its steady-state angle is determined by a competition between the size difference and the Reynolds number. When the sizes of the spheres are exactly equal, then fluid inertia causes the dumbbell to settle in a horizontal orientation.

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