Shape-Shifting Thermoresponsive Block Copolymer Nano-Objects

• Published in: Journal of colloid and interface science 2023-03, Vol.634, p.906-920
• Main Authors: Hunter, Saul J., Armes, Steven P.
• Format: Article
• Language: English
• Subjects: Block copolymer self-assembly; Microscopy, Electron, Transmission; Nano-objects; Nanoparticles; Polymerisation-induced self-assembly; Polymerization; Polymers - chemistry; RAFT polymerisation; Temperature; Thermoresponsive; Water - chemistry
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2022.12.080

This Feature Article focuses on the rational design of ‘shape-shifting’ thermoresponsive diblock copolymer nano-objects prepared using 2‑hydroxypropyl methacrylate, 4‑hydroxybutyl acrylate or hydroxybutyl methacrylate. A subtle change in the partial degree of hydration of the permanently insoluble thermoresponsive block drives thermal transitions between spheres, worms, vesicles and lamellae. Potential applications for this fascinating new class of amphiphiles are suggested. [Display omitted] In this Feature Article, we review our recent progress in the design of shape-shifting thermoresponsive diblock copolymer nano-objects, which are prepared using various hydroxyl-functional (meth)acrylic monomers (e.g. 2‑hydroxypropyl methacrylate, 4‑hydroxybutyl acrylate or hydroxybutyl methacrylate) to generate the thermoresponsive block. Unlike traditional thermoresponsive polymers such as poly(N-isopropylacrylamide), there is no transition between soluble and insoluble polymer chains in aqueous solution. Instead, thermally driven transitions between a series of copolymer morphologies (e.g. spheres, worms, vesicles or lamellae) occur on adjusting the aqueous solution temperature owing to a subtle change in the partial degree of hydration of the permanently insoluble thermoresponsive block. Such remarkable self-assembly behavior is unprecedented in colloid science: no other amphiphilic diblock copolymer or surfactant system undergoes such behavior at a fixed chemical composition and concentration. Such shape-shifting nano-objects are characterized by transmission electron microscopy, dynamic light scattering, small-angle X-ray scattering, rheology and variable temperature 1H NMR spectroscopy. Potential applications for this fascinating new class of amphiphiles are briefly considered.