RAFT Polymerisation and Hypercrosslinking Improve Crosslink Homogeneity and Surface Area of Styrene Based PolyHIPEs

Area of Science:

• Polymer Chemistry
• Materials Science
• Nanotechnology

Background:

• Highly porous polymers are crucial for applications like adsorption and catalysis.
• Controlling polymer architecture, particularly porosity, is key to optimizing performance.
• Emulsion templating offers a route to creating complex polymer structures.

Purpose of the Study:

• To investigate the impact of polymerization mechanism (RAFT vs. FRP) on the porous characteristics of poly(styrene-co-divinylbenzene) polymers.
• To analyze the effect of subsequent hypercrosslinking on polymer porosity.
• To correlate polymerization method with resulting surface area and pore size distribution.

Main Methods:

• Synthesis of highly porous polymers using high internal phase emulsion templating.
• Comparison of Reversible Addition-Fragmentation chain transfer (RAFT) and Free Radical Polymerization (FRP) methods.
• Post-synthesis hypercrosslinking using di-tert-butyl peroxide.
• Characterization via gas adsorption and solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.

Main Results:

• RAFT polymerization resulted in significantly higher specific surface areas (60–150 m²/g) compared to FRP (20–35 m²/g).
• RAFT polymerization promoted homogeneous crosslink distribution, leading to increased mesopore volume and enhanced microporosity after hypercrosslinking.
• Hypercrosslinking increased micropore fraction by up to 10 times in RAFT-derived polymers compared to FRP-derived ones.

Conclusions:

• The choice of polymerization mechanism profoundly influences the porous structure of styrene-divinylbenzene copolymers.
• RAFT polymerization offers superior control over polymer network homogeneity and porosity development.
• RAFT-derived polymers exhibit significantly improved characteristics for applications requiring high surface area and accessible pores.