Microporous Polymers and Their Applications

By Owais AliReviewed by Frances BriggsSep 2 2025

Microporous polymers offer tunable porosity, high surface areas, and chemical versatility. They can be used to powerful effect in gas storage, carbon capture, remediation and catalysis. Here's how they work. 

Image Credit: John Danow/Shutterstock.com

What are Microporous Polymers?

Microporous organic polymers (MOPs) are composed entirely of covalently linked organic molecules. These materials are characterized by their high surface areas, permanent microporosity, and structural tunability, properties that stem from their rigid and often contorted nature.

MOPs can be amorphous, such as hypercrosslinked polymers (HCPs), or crystalline, like covalent organic frameworks (COFs), or a mix of the two. This structural flexibility allows for the integration of a huge range of functional groups, and the design of polymers that are precisely tailored for specific chemical and physical requirements.

This versatility enables fine control over properties such as pore size distribution or chemical reactivity, making these materials suitable for demanding applications across scientific fields.¹

Types of Microporous Polymers

Microporous polymers are generally grouped by their structural order and the nature of their pore networks. One of the most well established are polymers of intrinsic microporosity (PIMs), amorphous materials constructed from rigid and non-planar monomers. Their inability to pack efficiently, due to their monomer counterparts, results in a permanent micropore structure and high surface areas. 

Hypercrosslinked polymers are slightly different. They are formed through extensive crosslinking reactions that create a densely connected network that is both resilient and highly porous. 

In contrast, covalent organic frameworks rely on reversible covalent bonds to create ordered, crystalline lattices with highly uniform but tunable pores. 

Conjugated microporous polymers (CMPs) are another well known group, consisting of π-conjugated networks with rigid, extended backbones. These structures provide permanent porosity and electronic conductivity, making them suitable for catalysis, sensing, and energy applications.²

Synthesis Methods

As there is a broad range of types of microporous polymers, so there is a large variety of synthesis methods. Researchers can customize pore structure, chemical functionality, and physical properties via a range of techniques and conditions. Microporous polymers can be prepared at ambient temperatures, across a range of solvents, with or without catalysts, and with differing reaction timescales.

Metal-Catalyzed and Metal-Mediated Polymerizations

Metal-catalyzed and metal-mediated approaches are among the most widely used approaches. These methods use transition metal catalysts to facilitate different coupling reactions, like the Suzuki catalysis or Buchwald-Hartwig reaction. 

These coupling catalyses allow precise control over polymer connectivity and the incorporation of functional groups, ensuring high surface areas, structural rigidity, and chemical stability—or whatever property is being sought after.

Polycondensation and Click-Type Reactions

Polycondensation reactions connect monomers through acid- or base-catalyzed processes to form frameworks such as polyamides, polyimides, benzimidazoles, dioxanes, boroxines, and imines.

Click-type reactions offer modular and efficient synthetic routes. They often proceed under mild or catalyst-free conditions, producing microporous polymers with well-defined networks and chemical functionalities.

Both reactions yield well-defined networks with tunable porosity and functional groups, and are compatible with scalable manufacturing.^1,3

Catalyzed Oxidative Polymerization

Oxidative polymerization with non-noble metal catalysts is an emerging approach that offers a cost-effective and environmentally friendly synthesis of microporous polymers. This method addresses several limitations of noble metal-catalyzed methods, including high cost, oxygen sensitivity, and challenging catalyst recovery.

Common reactions include Schiff base addition, oxidative coupling, Friedel-Crafts reactions, phenazine ring fusion, cyclotrimerization, and heterocyclic linkage formation.

A recent study published in Small exemplifies this. Using FeCl₃-mediated oxidative polymerization to synthesize carbazole- and porphyrin-based CMPs, the reaction produced stable, interconnected pore networks with high BET surface areas (510-1430 m²/g) and uniform microporosity.

The resulting materials exhibited significant adsorption capacities for CO₂, CO, H₂, and CH₄, along with luminescent properties and abundant nitrogen sites, enabling applications in renewable fuel storage, photocatalysis, and environmental engineering.⁴

Advantages of Microporous Polymers

Microporous polymers are highly versatile, creating diverse network structures with a wide range of chemical functionalities. Their organic building blocks enable tailored architectures and tuning of material properties. These polymers are lightweight, possess high surface areas, and maintain permanent porosity with adjustable pore sizes.

Additionally, most microporous polymers exhibit good chemical and thermal stability, allowing safe handling and modification under standard laboratory conditions without compromising structural integrity or porosity.²

So, how are they being used outside of the lab?

Download your PDF now to learn more about microporous polymers.

Hydrogen Adsorption

Microporous polymers are a strong candidate for safe hydrogen storage. Their potential here is significant, as storing hydrogen safely and compactly is a major challenge in advancing this clean technology. 

With their high surface areas, tunable pore structures, and lightweight composition, microporous polymers show promising H₂ adsorption.

For example, HCPs demonstrate reversible H₂ uptake of up to 5.4 wt% at 77 K, while PIMs and COFs achieve two to three wt% under cryogenic conditions.

CMPs and PAFs exhibit superior capacities, with PAF-1 reaching 7.0 wt% H₂ uptake at 48 bar and 77 K, demonstrating that engineered microporosity and functional group incorporation directly enhance hydrogen storage performance.¹

Carbon Capture

Microporous polymers serve as highly effective materials for carbon capture owing to their large surface areas, chemical and thermal stability, and tunable pore structure. In contrast to conventional amine-based solvents, these polymers can achieve enhanced CO₂ adsorption through precise structural and functional design.

Covalent organic frameworks such as COF-102 reach CO₂ uptakes of 1200 mg g^-1 at 55 bar and 298 K, while porous aromatic frameworks like PAF-1 attain 29.5 mmol?g^-1 under 40 bar at 298 K, highlighting their potential for efficient and scalable carbon capture technologies.

They're particularly useful as a replacement for these amine-based adsorbers, as they are less toxic and have much better energy efficiencies. 

Membrane Separation

Perhaps one of the most noteworthy uses of thse polymers are their separation capabilities. Their precisely tunable pore size facilitate molecular seiving on an exact level, making them effective in separating specific gases and complex liquid mixtures. 

HCPs are already used in chromatographic separations, solid-phase extraction, and removal of toxic organic and inorganic contaminants. PIMS, due to their processability into thin films, have shown high-permeability-selectivity ratios in separating CO₂/CH₄ and O₂/N₂ gases. 

A recent study by researchers at MIT revealed a polyimine-based membrane capable of separating crude oil components by molecular size. Adapted from reverse osmosis membrane ideas, the material uses rigid imine bonds and triptycene-derived monomers to form stable, selective pores that resist swelling.

They are a low-energy alternative to conventional distillation processes that contribute approximately 6 % of global CO₂ emissions.

When tested with mixtures such as toluene/triisopropylbenzene and industrial naphtha/kerosene/diesel, the membranes demonstrated high selectivity and permeance, efficiently partitioning light and heavy hydrocarbons.⁵

Catalysis

Conjugated microporous polymers are also highly effective heterogeneous catalysts.

Different metal complexes, such as Fe, Ru, Ir, or Co, can be incorporated into their pores, which has proven effective in facilitating oxidation, alkylation, and visible-light-driven photocatalysis. Studies have shown high turnover frequencies and excellent recyclability using CMPs as a heterogeneous catalyst.^1,2

Smart Membranes for Photoinduced Ion Control

In a study published in Science Advances, researchers engineered artificial light-gated ion channel membranes based on azobenzene-functionalized conjugated microporous polymers (azo-CMPs). These membranes feature well-defined micropores capable of reversible trans-cis-trans photoisomerization, enabling precise control over the transport of ions such as H⁺, K⁺, Na⁺, Li⁺, Ca²⁺, Mg²⁺, and Al³⁺.

These membranes may have potential in smart drug delivery systems, facilitating controlled, light-triggered release of therapeutic ions or molecules.

Additionally, they can function as photoresponsive chemosensors for rapid and reversible ion detection and as nanoscale molecular memory devices, exploiting light-induced ion transport for information storage at the molecular level.⁶

Current Challenges and Future Outlook

Microporous organic polymers face several challenges that are limiting their widespread application.

High production costs, the use of volatile organic solvents, and poor atom economy in some synthetic routes pose economic and environmental concerns. Additionally, the rigidity required to maintain high surface areas can reduce pore stability, and the largely aromatic backbones of MOPs exhibit low degradability, raising long-term sustainability issues.

Future research will focus on developing greener, cost-effective, and recyclable synthesis methods, enhancing mechanical and pore stability, and integrating functional groups to optimize performance. Computational modeling and advanced design strategies may enable tailored architectures for applications in energy storage, separations, and catalysis.

References and Further Reading

1. Chaoui, N., Trunk, M., Dawson, R., Schmidt, J., & Thomas, A. (2017). Trends and challenges for microporous polymers. Chemical Society Reviews, 46(11), 3302–3321. https://doi.org/10.1039/c7cs00071e
2. Xu, S., & Tan, B. Microporous Organic Polymers: Synthesis, Types, and Applications. 125-164. https://doi.org/10.1002/9781118860168.ch6
3. Ali, H., et al. (2025). Novel advancements in synthesis, modulation, and potential applications of conjugated microporous polymer-based materials. Nano Materials Science. https://doi.org/10.1016/j.nanoms.2024.08.008
4. Chen, Q., Liu, P., Luo, M., Feng, J., Zhao, C., & Han, H. (2013). Nitrogen-Containing Microporous Conjugated Polymers via Carbazole-Based Oxidative Coupling Polymerization: Preparation, Porosity, and Gas Uptake. Small, 10(2), 308-315. https://doi.org/10.1002/smll.201301618
5. Trafton, A. (2025, May). A new approach could fractionate crude oil using much less energy. MIT News. https://news.mit.edu/2025/new-approach-could-fractionate-crude-oil-using-less-energy-0522
6. Zhou, Z., et al. (2022). Conjugated microporous polymer membranes for light-gated ion transport. Science Advances. https://doi.org/abo2929

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