Controlling the roll-to-helix transformation in electron-beam-patterned gel-based micro-ribbons
Xinpei Wu1, Teng Zhang2, Matthew Libera1
1Department of Chemical Engineering and Materials Science, Stevens Institute of Technology, Hoboken, NJ, USA. mlibera@stevens.edu.
Soft Matter
|September 30, 2024
Summary
Researchers created microscale ribbons from poly(acrylic acid) using electron-beam patterning. These ribbons transition from rolls to helices, with shape controlled by pH and gap orientation, mimicking rigid origami metamaterials.
Area of Science:
- Materials Science
- Polymer Science
- Nanotechnology
Background:
- Helix formation is crucial in natural and synthetic systems.
- Previous studies focused on gel ribbons and mechanical bilayer construction.
- Electron-beam patterning offers a novel approach for microscale ribbon fabrication.
Purpose of the Study:
- To investigate helix formation in microscale poly(acrylic acid) ribbons fabricated via electron-beam patterning.
- To explore the influence of pH and structural anisotropy on ribbon morphology.
- To understand the role of anisotropic swelling in creating complex 3D structures.
Main Methods:
- Fabrication of microscale ribbons (1-100 μm) from poly(acrylic acid) using electron-beam patterning.
- Characterization of ribbon conformations including rolls, helices, and transition structures.
- Finite-element modeling to simulate ribbon behavior and validate experimental observations.
- pH variation and patterning with micro-tiles and gaps to induce anisotropy.
Main Results:
- Electron-beam patterning created ribbons with distinct hydrophobic (crosslinked) and hydrophilic (gel) layers.
- Ribbons exhibited transitions from rolls to helices with increasing aspect ratio.
- Increasing pH induced plastic deformation and formation of nonminimal-pitch helices.
- Patterning with gaps resulted in a roll-to-helix-to-tube transition, with chirality determined by gap orientation.
Conclusions:
- Electron-beam patterning provides a versatile method for creating microscale ribbons with tunable morphologies.
- pH-induced swelling and patterned anisotropy are key factors controlling helix formation and pitch.
- The micro-composite ribbons function as rigid origami metamaterials, where deformation at gap creases dictates shape shifting.
Related Concept Videos
02:06Newman Projections
Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
01:08Spin–Spin Coupling Constant: Overview
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 have a...
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 have a...
01:17Spin–Spin Coupling: One-Bond Coupling
Coupling interactions are strongest between NMR-active nuclei bonded to each other, where spin information can be transmitted directly through the pair of bonding electrons. While nuclei polarize their electrons to the opposite spins, the bonding electron pair has opposite spins. Configurations with antiparallel nuclear spins are expected to be lower in energy. When coupling makes antiparallel states more favorable, J is considered to have a positive value. The one-bond coupling constant, 1J,...