Polymerization-induced self-assembly of thermoresponsive micelles and their lubrication adaptivity

Abstract

Responsive materials have significant application value because of their ability to actively adjust their structure or properties in response to external stimuli. Poly(N-isopropylacrylamide) (PNIPAM) is widely used to form micelles, particularly for drug delivery, because its lower critical solution temperature (LCST) is close to body temperature. However, the preparation of micelles based on PNIPAM block copolymers often involves complex processes, which limit their broader application. Here, we employed polymerization-induced self-assembly (PISA) combined with in situ crosslinking to synthesize stabilized thermoresponsive micelles, such as poly(glycerol methacrylate)-b-poly(N-isopropylacrylamide)-B (PGMAx-b-PNIPAMy-B), which are spherical micelles with a thermoresponsive core of PNIPAM and a crosslinked shell of PGMA formed by sodium tetraborate decahydrate. The micelles exhibited rapid and reversible self-assembly and collapsed at 31 °C, enabling temperature regulation through light transmittance, which makes them suitable for smart window applications. Furthermore, these micelles demonstrated excellent friction-reducing and wear-resistant properties at various temperatures (25–36 °C) and under various loads (20–70 N), indicating their adaptive lubrication as additives. This work presents the facile fabrication of thermoresponsive micelles and expands the application of PISA technology in the tribological field. Responsive materials have significant application value because of their ability to actively adjust their structure or properties in response to external stimuli. We employed polymerization-induced self-assembly combined with in situ crosslinking to synthesize stabilized thermoresponsive micelles, such as poly(glycerol methacrylate)-b-poly(N-isopropylacrylamide)-B, which exhibited rapid and reversible self-assembly. Furthermore, these micelles demonstrated excellent friction-reducing and wear-resistant properties showcasing their adaptive lubrication as additives. This work presents the facile fabrication of thermoresponsive micelles and expands the application of PISA technology in the tribological field.