Stimuli-Responsive Control over Self-Assembled Nanostructures in Sequence-Specific Functional Block Copolymers

Abstract

The precise sequence of a protein's primary structure is essential in determining its folding pathways. To emulate the complexity of these biomolecules, functional block copolymers consisting of segmented triblocks with distinct functionalities positioned in a sequence-specific manner are designed to control the polymer chain compaction. Triblock polymers P-b-C-b-F and P-b-F-b-C and random diblock copolymer P-b-C-r-F consist of a hydrophilic poly(ethylene oxide) (PEO) block and a hydrophobic block with coumarin (C) and ferrocene (F) moieties that are grafted in a sequence-specific or random manner onto the hydrophilic block. External stimuli such as UV B light, redox, and chemical cues influence the functional hydrophobic block to alter the packing parameters that are monitored with spectroscopic and scattering techniques. Interestingly, the positioning of the stimuli-responsive moiety within the hydrophobic block of P-b-C-b-F, P-b-F-b-C, and P-b-C-r-F affects the extent of the hydrophobic−hydrophilic balance in block copolymers that renders orthogonal control in stimuli-responsive transformation of self-assembled vesicles to micelles.