Networking of block copolymer nanoassemblies via digital light processing four-dimensional printing for programmable actuation

Controls over stimuli-responsive functional materials and programmable shape deformations are key features in the four-dimensional (4D) printing of soft actuators. Instead of using random copolymers, homopolymers, or natural polymers, this paper reports the first use of amphiphilic, photocurable, and pH-responsive block copolymer (BCP) nanoassemblies in digital light processing (DLP) 4D printing to fabricate smart and programmable soft actuators. Programmable actuation was studied via a bottom-up approach: (1) designed synthesis of pH-responsive BCPs, (2) nanoassembly structures of BCPs, and (3) networking of nanoassemblies via the photocuring process in DLP. As a proof-of-concept, bilayered grippers, ring-shaped actuators, and octopus-like actuators were programmed to produce a range of bending angles and actuation patterns. pH-responsive BCP nanoassemblies were also combined with commercially available three-dimensional printing liquid resin (PlasClear) to produce stimulus-responsive printing ink that was successfully used for 4D printing applications. Thus, smart and programmable materials were developed for 4D printing applications.National Research Foundation (NRF)Submitted/Accepted versionThis work was supported by National Research Foundation (NRF) Investigatorship in Singapore (NRF-NRFI05-2019-0001)