UV Light and Temperature Responsive Supramolecular ABA Triblock Copolymers via Reversible Cyclodextrin Complexation

Abstract

A novel triblock macromolecular architecture based on cyclodextrin (CD) complexation is presented. A CD-functionalized biocompatible poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) building block (3800 ≤ Mn ≤ 10 600 g mol–1; 1.29 ≤ ĐM ≤ 1.46) and doubly guest-containing poly(N,N-dimethylacrylamide) (PDMAAm) (6400 ≤ Mn ≤ 15 700 g mol–1; 1.06 ≤ ĐM ≤ 1.15) and poly(N,N-diethylacrylamide) (PDEAAm) (5400 ≤ Mn ≤ 12 100 g mol–1; 1.11 ≤ ĐM ≤ 1.33) segments were prepared via reversible addition–fragmentation chain transfer (RAFT) polymerization and subsequently utilized for the formation of a well-defined supramolecular ABA triblock copolymer. The block formation was evidenced via dynamic light scattering (DLS), nuclear Overhauser effect spectroscopy (NOESY), and turbidity measurements. Furthermore, the connection of the blocks was proven to be temperature responsive and—in the case of azobenzene guests—responsive to the irradiation with UV light. The application of these stimuli leads to the disassembly of the triblock copolymer, which was shown to be reversible. In the case of PDEAAm containing triblock copolymers, the temperature-induced aggregation was investigated as well.