Related Experiment Video
Updated: Oct 29, 2025
08:37
Forming, Confining, and Observing Microtubule-Based Active Nematics
Published on: January 13, 2023
2.9K
Twisted loxodromes in spindle-shaped polymer nematics
Helen S Ansell1, Randall D Kamien1
1Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. ansellh@sas.upenn.edu.
Soft Matter
|July 8, 2021
Summary
We developed an energetic model for twisting polymer microparticles, revealing loxodrome spirals are energetically favorable. This model captures unique nematic ordering in spindle shapes, differing from standard nematics.
Area of Science:
- Soft Matter Physics
- Polymer Science
- Materials Science
Background:
- Spindle-shaped polymer microparticles exhibit unique twisting behavior due to nematic ordering.
- Previous geometric models described this twist as following loxodrome spirals.
Purpose of the Study:
- To develop an energetic model for the twisting behavior of spindle-shaped polymer microparticles.
- To investigate the energetic favorability of loxodrome spiral twisting patterns in nematic systems.
Main Methods:
- Formulating an energetic model based on Frank free energy for nematic systems.
- Incorporating an additional term to constrain integral curve lengths on spindle surfaces.
- Extending the model to bulk systems and analyzing parameter space.
Main Results:
- The energetic model successfully captures the loxodrome twisting behavior observed in experiments.
- The Frank free energy with a length-constraint term explains the observed twist patterns.
- The study identifies conditions under which the twisted loxodrome solution is energetically favorable in bulk systems.
Conclusions:
- The developed energetic model provides a theoretical framework for understanding the unique twisting of spindle-shaped polymer microparticles.
- Loxodrome spirals are confirmed as energetically favorable twisting patterns in this specific nematic system.
- The findings offer insights into the self-assembly and behavior of anisotropic microparticles.
Related Concept Videos
01:08Spin–Spin Coupling Constant: Overview
1.1K
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
1.1K
01:14Generation of Straight or Branched Actin Filaments
3.2K
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
3.2K
01:18Polarity of the Cytoskeleton
21.1K
The intrinsic polarity of cells can be primarily attributed to two factors- i) the asymmetric accumulation of mobile components such are regulatory molecules and subcellular components across the cell and ii) the orientation of polar cytoskeletal filaments that make up the cytoskeletal networks, specifically microfilaments, and microtubules arranged along the axis of polarity. Interactions between the cytoskeletal filaments are crucial for the establishment and maintenance of the polar nature...
21.1K
01:17Ziegler–Natta Chain-Growth Polymerization: Overview
3.5K
Ziegler–Natta polymerization is another form of addition or chain‐growth polymerization used for synthesizing linear polymers over branched polymers. The catalyst used for polymerization is the Ziegler–Natta catalyst, named after Karl Ziegler and Giulio Natta, who developed it in 1953. This catalyst is an organometallic complex of titanium tetrachloride and triethyl aluminum, with the active form of the catalyst being an alkyl titanium compound. Using the Ziegler–Natta...
3.5K
01:13Angle of Twist - Elastic Range
508
Consider a cylindrical shaft with a length denoted by L and a consistent cross-sectional radius referred to as r. This shaft undergoes a torque at the free end. The highest shearing strain within the shaft is directly proportional to the twist angle and the radial distance from the shaft axis. When the shaft behaves elastically, this shearing strain can be articulated using variables such as the applied torque, radial distance, the polar moment of inertia, and the modulus of rigidity. By...
508
01:16Eccentric Axial Loading in a Plane of Symmetry
361
Eccentric axial loading occurs when an axial load is applied away from the centroidal axis of a structural member. This scenario is common in engineering, where structural elements may not be directly aligned due to various design or functional requirements.
361