Second-Generation Soft Actuators Driven by NIR Light Based on Croconaine Dye-Doped Vitrimers.

Soft actuators with photo-response can be selectively driven by the light source, but it is challenging to achieve a selective response of multiple components under a uniform light field, which is actually of great importance for the development of soft robots. In this work, a series of near-infrared light (NIR)-responsive vitrimers (CR-vitrimers) are synthesized by carboxylate transesterification using carboxyl-bearing croconaine dye (CR-800) as a photothermal agent (PTA). NIR-responsive liquid crystalline elastomers (CR-vitrimer-LCEs) under NIR laser (λ = 808 nm) without the template can be further prepared.

Hierarchical Self-Assembly of Triphilic Main-Chain-Type Semifluorinated Alternating Graft Copolymers in Aqueous Solution.

Fluorinated copolymers can self-assemble in solution and form micelles with rare properties due to the peculiar behavior of fluorinated groups. However, the process description of the self-assembly is still largely phenomenological and difficult to explain due to the tendency of the fluorinated segments to segregate from both the hydrophilic and lipophilic segments, which can result in various morphologies. Herein, the controlled formation of ellipsoidal micelles, disklike micelles, and sheets by hierarchical self-assembly of triphilic main-chain-type semifluorinated alternating graft copolymers (AB) A-g-mOEG is presented (where A represents unit of α,ω-diiodoperfluoroalkane, B represents the unit of α,ω-unconjugated diene, and mOEG represents methoxy oligo(ethylene glycol)), which are synthesized by step transfer-addition and radical-termination (START) polymerization and azide-alkyne click chemistry.

Synthesis and Phase Behavior of (Semifluorinated Alkane)-Based Side-Chain Liquid Crystalline Copolymers.

Side-chain liquid crystalline polymer (SCLCP) usually contains a simple and flexible homopolymer as main chain, while its effect on the self-assembly behavior is often ignored. In this work, in order to increase the structural complexity and investigate the interaction between the main chain and mesogens, perfluorinated segments are introduced into the main chain using a photoinduced Step Transfer-Addition & Radical-Termination polymerization method, producing a novel series of SCLCPs containing 4-methoxyphenyl benzoate mesogens, soft hydrocarbon spacers, and a strictly alternating perfluoroalkyl and alkyl backbone. By adjusting the length of spacers or perfluoroalkyl segments, several mesophases with complex chain packing structures are achieved.

Reduction-Induced Crystallization-Driven Self-Assembly of Main-Chain-Type Alternating Copolymers: Transformation from 1D Lines to 2D Platelets.

In recent years, crystalline-driven self-assembly (CDSA) has received enormous attention, but almost only for block copolymers (BCPs). Herein, we introduced perfluorocarbon chains into main-chain-type liquid crystalline alternating copolymers (ACPs) to obtain perfluoroalkane-containing ACPs with periodic C-I bonds in polymer backbones via step transfer-addition and radical-termination (START) polymerization, followed by an iodine reduction reaction of C-I bonds to induce CDSA of ACPs and put forward a novel concept of "reduction-induced crystallization-driven self-assembly" (RI-CDSA) of main-chain-type ACPs for the first time. Finally, we proposed the folded-chain model and mechanism to explain the novel RI-CDSA behavior, and its rationality has been proved by the corresponding experimental results.

An alternating conduction-insulation "molecular fence" model from fluorinated metallopolymers.

Introducing fluoroalkyl chains into metallopolymers is a prerequisite to studying the self-organization effect of fluoroalkyl chains and their structure-property relationship. In this work, we present a fluorinated metallopolymer to build an alternating conduction-insulation "molecular fence" model synthesized by the coordination of Ru(II) and a bis-terpyridine-end-capped-phenyl (BTP) ligand modified with fluoroalkyl chains. Taking advantage of scanning tunneling microscopy (STM), a well-aligned periodic linear layered structure is observed clearly, which provides the most direct visualization of the self-organization effect of fluoroalkyl chains for the first time.

Facile photochemical synthesis of main-chain-type semifluorinated alternating copolymers catalyzed by conventional amines or halide salts.

In this work, we report a much simpler and low-cost method to prepare main-chain-type semifluorinated alternating copolymers by the formation of a halogen bond (XB) complex between α,ω-diiodoperfluoroalkanes and amines/halide salts. It is interesting that the terminal iodine functional group of the polymer chains is easily lost in the amine-promoted system, while the loss can be significantly reduced by adding a small amount of water. Importantly, the system promoted by halide salts can ensure complete retention of the iodine functional group.

Organocatalytic Approach to Functional Semifluorinated Polymers Driven by Visible Light.

Through the construction of an organic photocatalysis system, photoredox catalyst (PC)/additive, where PC stands for photoredox catalyst, an organocatalyzed step transfer-addition and radical-termination (O-START) polymerization irradiated by blue LED light at room temperature is realized. Different types of α,ω-diiodoperfluoroalkane A and α,ω-unconjugated diene B are copolymerized through O-START efficiently, and generate various kinds of functional semifluorinated polymers, including polyolefins and polyesters. The process is affected by several factors; solvents, additives, and feed ratio of A to B.