Morphological control of hybrid amphiphilic poly(N-isopropylacrylamide)/metal cyanide complexes

Abstract

A number of amphiphilic N-isopropylacrylamide (NIPAAm) oligomers and polymers with a S-1-dodecyl-S′-trithiocarbonate (DTC) and an amino terminal group were prepared using RAFT polymerization: DTC-NIPAAm 13 -NH 3 Cl (1), DTC-NIPAAm 61 -NH 3 Cl (2), DTC-NIPAAm 78 -NH 3 Cl (3), DTC-NIPAAm 119 -NH 3 Cl (4). and DTC-NIPAAm 274 -NH 3 Cl (5). Aqueous solutions of 1-5 became cloudy upon heating at pH 10, while 1-4 did not exhibit thermosensitivity at pH 7.0, instead forming stable rods and vesicles in aqueous solution. Nanorods and nanosquares were obtained from metal cyanide complexes of 1 and 2, both of which had low degrees of polymerization, and aqueous solutions of these nanocomposites became cloudy at pH 7.0. The electrostatic interactions between the amine segments and the anionic metal cyanide complexes as well as the low degree of polymerization in the vicinity of approximately 100 were both found to have a significant role in the morphology and thermoresponsiveness of the hybrids. These hybrid NIPAAm oligomer/metal cyanide complexes may allow the design of flexible, functional supramolecular systems in aqueous solutions.