Anionic amphiphilic model conetworks synthesized by end-linking of tetra-arm copolymers

- Model amphiphilic conetworks of sodium acrylate and methyl acrylate were prepared.
- Degrees of swelling depended on monomer sequences and external salt concentration.
- Block conetwork showed salt-responsive uptake and release of a hydrophobic compound.

Highly homogeneous block and random amphiphilic conetworks (APCNs) of sodium acrylate (NaA) and methyl acrylate (MA) with the same composition (NaA/MA ∼ 2/1) were synthesized via end-linking reaction between tetra-arm copolymers of tert-butyl acrylate and MA by copper-catalyzed azide-alkyne cycloaddition followed by the removal of the protecting tert-butyl group and neutralization. Measurement of the degrees of swelling in saline (Qs) and in pure water (Qpw) showed that the ratio of Qs to Qpw for the random APCNs was similar to that for homopolymer networks of NaA, whereas it was significantly smaller for the block APCNs. The result indicated that hydrophobic interaction between PMA blocks was induced by added salt. Taking advantage of the salt-responsive property of the block APCNs, their ability to capture and release a hydrophobic compound was investigated by confocal laser scanning microscopy using fluorescein as a probe molecule.

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