Hello! Yes, It is possible, at least it works for chitosan. R-NH2 -->:Ag ; R-NH2 -->:Pd ; R-NH2 -->:Au ; R-NH2 -->:Cu etc Article Chitosan Glutaraldegyde Cryogels for Wastewater Treatment an...

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Hi

Gold and sulfide (Au and SH___R___SH)

Cu2+ and Amine (Like Cu2+ and chitosan)

Zn2+ and Fe2+ and carboxilic acid-based polymers (Like Zn2+ and poly amic acid, Fe2+ and polyacrylic acid)

Zn2+ and imidazole-functionalized polymer

and ...

Hello,

as Dmitriy Berillo and Alireza Shaabani mentioned there are some ions, which can be used for this purpose and from their examples, you can derive, that the charge of the ions needs to be larger than +1 so the ion can form a bridge between two polymer chains.

As an example, ions like Li+, Na+, K+ could only attach to one ligand in polyacrylic acid (PAA), whereas ions like Ca2+, Mg2+,... could form a bridge between two polymer chains, or more polymer chains, if you do not consider a single ion but the complete system.

Thanks, Dmitriy Berillo, Alireza Shaabani, and Matthias Heck for your explanation.

I have some further questions regarding this matter. What if there is a mixture of Na+ and Ca2+ ions? Is the ligand more likely to bind to one of the ions? In this case, can the presence of Na+ ions inhibit the cross-links in the polymer?

Regarding the mixture of ions, I would have to guess: There's the so-called HSAB (hard and soft acids and bases) principle to estimate how much cations and anions like each other (and form a crystal as an example).

In this context 'hard' equals a high amount of charge localized on a small ion and 'soft' equals a low amount of charge localized on a large ion.

I think the possibility of Na+ to inhibit the crosslinking depends on the size of your ligand and it's charge. I would estimate that Na+ or another ion with a charge of +1 has a negative impact on the ability to crosslink your polymer via other metal ions with higher charges.

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