Structure and Ultrasonic Sensitivity of the Superparticles Formed by Self-Assembly of Single Chain Janus Nanoparticles

Abstract

Single chain Janus nanoparticles (SCJNPs) (tadpole-like Janus nanoparticles) with a PEO (poly(ethylene oxide)) chain as the “tail” and a cross-linked PCEMA (poly(2-cinnamoyloxyethyl methacrylate)) chain as the “head” were synthesized conveniently and efficiently by directly photo-cross-linking PCEMA block of PEO-b-PCEMA diblock copolymer in the common solvent DMF; intramolecular cross-linking occurred dominantly at a relatively high concentration of the copolymer when the cross-linking speed is relatively low, leading to SCJNPs. In selective solvent for the “tails”, the rigid “heads” aggregated into superparticles. It is significant that under a gentle ultrasonic treatment (40 kHz for 10 min) the spherical superparticles formed in DMF/ethanol (1/4, v/v) dissociated into individual SCJNPs. It is also demonstrated that even in pure water in which the superparticles have a more closely aggregated structure, there are still hydrophilic channels within the superparticles connecting the surrounding medium and t...