β-Cyclodextrin-derived diallylamine salt: Synthesis and its copolymerizations

A diallyl amine salt monomer bearing a β-CD substituent was cyclopolymerized for the first time. The reaction of 6-O-toluenesulfonyl-β-cyclodextrin [(C₆H₁₀O₅)₆-(C₅H₇)]-CH₂OTs with diallylamine followed by protonation afforded the diallylamine salt monomer [(C₆H₁₀O₅)₆-(C₅H₇)]-CH₂NH⁺(CH₂CH=CH₂)₂ Cl^-] (I). The cyclopolymerization of monomer I and its copolymerization with monomer [Me₂N⁺(CH₂CH=CH₂)₂ Cl^-] (II), [^-O₂CCH₂NH⁺(CH₂CH=CH₂)₂] (III), [H₂O₃PCH₂NH⁺(CH₂CH=CH₂)₂ Cl^-] (IV) or [HO₂CCH₂CH(CO₂H)NH⁺(CH₂CH=CH₂)₂ Cl^-] (V) yielded a series of copolymers having residues of β-CD and glycine or methyl phosphonate or aspartic acid. Terpolymerization in the presence of SO₂ afforded polymers with alternating placements of the SO₂ units. The solution properties of the pH-responsive polyzwitterions, including their viscosity, were examined. The water-insoluble terpolymer I/V/SO₂ with 20 mol% β-CD residues removed the organic micropollutant 2-naphthol from an aqueous system via host/guest complexation. This work paves the way for the possible synthesis of cross-linked polymers that can simultaneously remove organic micropollutants and toxic metal ions (by complexation with the chelating glycine, aspartic acid, and aminomethyl phosphonate ligands) from contaminated aqueous systems.