Polymerization-induced self-assembly (PISA) via reversible addition−fragmentation chain transfer (RAFT) dispersion polymerization is an effective method to produce block copolymer nano-objects of various morphologies at high solids. However, current PISA formulations have been limited to linear block copolymers. We report the synthesis of AB 2 star block copolymers via RAFT aqueous dispersion polymerization of diacetone acrylamide using a poly(ethylene glycol) methyl ether bearing two chain transfer agents as the difunctional macromolecular chain transfer agent (macro-CTA), which was efficiently synthesized using 2,4,6trichloro-1,3,5-triazine and activated esters to afford a high end functionality (97%). The star polymer architecture can significantly promote morphological transitions to obtain higher-order morphologies at both lower solids and lower degrees of polymerization of the core-forming block in comparison with its linear counterpart. This work demonstrates that polymer architecture is another important parameter that should be considered when conducting PISA synthesis to obtain complex morphologies.

Conductive hydrogels had demonstrated significant prospect in the field of wearable devices. However, hydrogels suffer from a huge limitation of freezing when the temperature falls below zero. Here, a novel conductive organohydrogel was developed by introducing polyelectrolytes and glycerol into hydrogels. The gel exhibited excellent elongation, self-healing, and self-adhesive performance for various materials. Moreover, the gel could withstand a low temperature of −20 °C for 24 h without freezing and still maintain good conductivity and self-healing properties. As a result, the sample could be applied for motion detection and signal transmission. For example, it can respond to finger movements and transmit network signals like network cables. Therefore, it was envisioned that the effective design strategy for conductive organohydrogels with antifreezing, toughness, self-healing, and self-adhesive properties would provide wide applications of flexible wearable devices.

Polymerization-induced self-assembly is demonstrated as a powerful platform for the synthesis of block copolymers comprising a semifluorinated liquid-crystalline block. This strategy transforms the deficiency of polymer insolubility encountered in traditional homogeneous solution protocols to the strength for dispersion polymerization, thus, enabling direct access to polymorphic block copolymer nanoobjects at high concentrations and with quantitative conversions. The versatility of this strategy is highlighted by polymerizations in a wide selection of inexpensive solvents, from nonpolar to highly polar, to afford various block copolymers with distinct combinations of amorphous/crystalline or hydrophilic/hydrophobic/fluorinated segments. The utility of the nanoparticles is demonstrated as robust Pickering emulsifiers for commonly considered good solvents.

Block copolymer worm stabilization via cross-linking during polymerization-induced self-assembly (PISA) is challenging. This is because block copolymer worms typically occupy a narrow regime in the phase diagram, and in situ cross-linking may hinder a morphological transition from sphere to worm. In this work, in situ cross-linking of block copolymer worms during PISA was studied using three different asymmetric cross-linkers, each bearing a pair of double bonds with different reactivities. Specifically, ethanolic PISA syntheses targeting poly­(2-(dimethyl­amino)­ethyl methacrylate)-b-poly­(benzyl methacrylate) diblock copolymer worms were investigated in the presence of vinyl methacrylate, allyl methacrylate, or 4-allyloxybenzyl methacrylate. The copolymerizations of benzyl methacrylate with the asymmetric cross-linkers underwent progressive branching to finally cross-linking of the block copolymer worms. While all the three asymmetric cross-linkers were able to cross-link worms, 4-allyloxybenzyl methacrylate with a structure mimicking benzyl methacrylate showed the best results with minimal perturbation to the worm morphology.

Traditional optoelectronic devices without stretchable performance could be limited for substrates with irregular shape. Therefore, it is urgent to explore a new generation of flexible, stretchable, and low-cost intelligent vehicles as visual display and storage devices, such as hydrogels. In the investigation, a novel photochromic hydrogel was developed by introducing the negatively charged ammonium molybdate as a photochromic unit into polyacrylamide via ionic and covalent cross-linking. The hydrogel exhibited excellent properties of low cost, easy preparation, stretchable deformation, fatigue resistance, high transparency, and second-order response to external signals. Moreover, the photochromic and fading process of hydrogels could be precisely controlled and repeated under the irradiation of UV light and exposure of oxygen at different time and temperature. The photochromic hydrogel could be considered applied for artificial intelligence system, wearable healthcare device, and flexible memory device. Therefore, the strategy for designing a soft photochromic material would open a new direction to manufacture flexible and stretchable devices.