Solid-Phase Radical Polymerization of Halogen-Bond-Based Crystals and Applications to Pre-Shaped Polymer Materials

Area of Science:

• Materials Science
• Polymer Chemistry
• Crystallography

Background:

• Traditional polymerization methods often face challenges in controlling polymer architecture and properties.
• Solid-state polymerization offers potential for high-fidelity structure formation but requires precise monomer alignment.

Purpose of the Study:

• To develop a method for creating highly aligned monomer crystals for controlled polymerization.
• To investigate the synthesis of polymers with controlled molecular weights and architectures via solid-phase polymerization.
• To explore the fabrication of complex polymer structures and their functional properties.

Main Methods:

• Liquid vinyl monomers were converted into solid crystals using halogen bonding.
• Solid-phase radical polymerization was achieved through thermal treatment (40°C) or UV irradiation (365 nm).
• X-ray crystallography was employed to analyze monomer alignment within the crystals.

Main Results:

• High degrees of monomer alignment were observed in the halogen-bonded crystals.
• Solid-phase polymerization yielded polymers with high molecular weights and low dispersities.
• Two-layer polymer sheets and 3D house-shaped polymer materials were successfully fabricated.
• The two-layer sheet demonstrated an asymmetric pore structure and solvent-responsive shape memory behavior.

Conclusions:

• Halogen bonding is an effective strategy for achieving precise monomer alignment in the solid state, facilitating controlled polymerization.
• Solid-phase polymerization of aligned monomers offers a route to high-performance polymers and complex macromolecular architectures.
• The developed system enables the creation of functional materials, such as asymmetric membranes and actuators, with unique properties.