Self-Accelerating Diels-Alder Reaction for Preparing Polymers of Intrinsic Microporosity

Area of Science:

• Polymer Chemistry
• Materials Science
• Organic Synthesis

Background:

• Preparing double-stranded polymers of intrinsic microporosity (PIMs) with fused multicyclic linkages via polycondensation presents significant challenges.
• Simultaneously constructing multiple covalent bonds is difficult, limiting the development of complex polymer architectures.

Purpose of the Study:

• To develop a novel method for synthesizing double-stranded PIMs with fused multicyclic backbones.
• To utilize a self-accelerating Diels-Alder reaction for efficient polymer construction.
• To investigate the properties and gas separation performance of the newly synthesized PIMs.

Main Methods:

• A self-accelerating Diels-Alder reaction was designed using sym-dibenzo-1,5-cyclooctadiene-3,7-diyne (DIBOD) and ortho-quinone compounds.
• The reaction involves a [4+2] cycloaddition where the reaction with the first alkyne activates the second alkyne, increasing the reaction rate 192-fold.
• A stoichiometric imbalance-promoted step-growth polymerization method was employed using DIBOD and difunctional ortho-quinone monomers.

Main Results:

• The self-accelerating Diels-Alder reaction successfully produced double-stranded PIMs with fused multicyclic backbone structures.
• The synthesized PIMs exhibit intrinsic ultramicropores (0.45–0.7 nm) and high specific surface areas (>646 m²/g).
• The PIMs demonstrated good hydrogen (H2) separation performance.

Conclusions:

• The developed self-accelerating Diels-Alder reaction provides an effective route to novel double-stranded PIMs.
• These PIMs possess desirable properties for gas separation applications, particularly for H2.
• This study represents a significant advancement in the synthesis of complex polymer architectures for advanced materials.