Spontaneous Long-Range Order and Alignment in Phase-Separated Dynamic Covalent Networks Using Discrete Siloxanes

Area of Science:

• Materials Science
• Polymer Chemistry
• Supramolecular Chemistry

Background:

• Dynamic covalent chemistry enables self-healing and adaptive materials.
• Achieving long-range order in covalent networks is challenging.
• Hydrogen bonding plays a key role in molecular self-assembly.

Purpose of the Study:

• To prepare dynamic covalent networks exhibiting spontaneous alignment and hexagonal columnar ordering.
• To investigate the role of siloxane linkers in network structure and properties.
• To develop a simplified method for creating ordered networks and actuators.

Main Methods:

• Synthesis of dynamic covalent networks using siloxane linkers and acylsemicarbazide bonds.
• Solvent evaporation technique for inducing network ordering and alignment.
• Characterization using transmission electron microscopy (TEM) and grazing incidence small-angle X-ray scattering (GISAXS).

Main Results:

• Spontaneous long-range hexagonal columnar ordering achieved through phase-separation.
• Discrete siloxane linkers are essential for ordered structures.
• Optimized siloxane length led to pronounced ordering and homeotropic alignment.
• Ordered networks exhibit enhanced (thermo)mechanical properties and creep resistance.
• Actuators fabricated by combining ordered and disordered networks without alignment steps.

Conclusions:

• Dynamic covalent networks with intrinsic order can be prepared via controlled phase-separation.
• Siloxane linker design is critical for achieving self-assembly and macroscopic properties.
• The developed method offers a simplified route to ordered materials and functional devices like actuators.