Metal-Organic Frameworks for Macromolecular Recognition and Separation

Abstract

Selective molecular adsorption using metal-organic frameworks (MOFs) has been firmly established as an effective technique in modern separation science. However, polymer insertion into MOFs remains inadequately investigated, probably owing to the large conformational disadvantages commonly associated with spontaneous intercalation processes. Meanwhile, it has been demonstrated that in situ formation of polymers is possible in well-designed nanochannels of MOFs. Being able to take full advantage of the polymer intercalation mechanism would help us devise powerful macromolecular recognition and separation technologies with unprecedented selectivity. Here, we discuss the prospects of polymer recognition using programmed MOF nanospaces, which can be realized via selective intercalation of polymer chains in MOF hosts. Designing nanosized porous MOFs with a regular arrangement of reactive/interactive/responsive entities offers the possibility of universal polymer recognition that cannot be accomplished by conventional methods.

Revisiting molecular adsorption: unconventional uptake of polymer chains from solution into sub-nanoporous media

“…Most recently, this polymer insertion phenomenon has been employed to discriminate between different polymer structures. [44][45][46][47][48] In this manner, MOFs recognize minute differences in polymer architectures upon an insertion event, thus allowing precise polymer separation. 47,48 However, a full understanding of the polymer insertion mechanism remains incomplete despite such prospective applications in the realm of materials science.…”

Study on the Adsorption of Hydrolyzed Polyacrylamide by Zeolitic Imidazole Framework

“…The main pore size of ZIF‐8(NH 3 ⋅ H 2 O) was 0.96 nm, the HPAM‐2 was very hard to adsorb into the pore size for its high molecular weight, which indicating that the insertion kinetics method established by Uemura [32,33] is not suitable for our study. Therefore, Thomas model was used to study the dynamic adsorption.…”

Metal‐Organic Frameworks for Practical Separation of Cyclic and Linear Polymers

“…MOFs have attracted considerable interest owing to their potential as gas storage and separation media [10] . Recently, it has been shown that MOF nanopores can also accommodate various polymers, [11] facilitating the precise recognition and separation of macromolecules [12, 13] . However, previously reported examples of MOF‐based polymer separation have not demonstrated the capacity for large‐scale operation via practical gram‐scale laboratory work‐ups.…”

“…[10] Recently, it has been shown that MOF nanopores can also accommodate various polymers, [11] facilitating the precise recognition and separation of macromolecules. [12,13] However, previously reported examples of MOF-based polymer separation have not demonstrated the capacity for large-scale operation via practical gram-scale laboratory work-ups. Therefore, despite the demand for the implementation of such methods in practical synthetic workflows, addressing both large-scale and precise discrimination of polymer architecture remains challenging.…”