Synthesis of Thermo‐, Oxidation‐, pH‐, and CO 2 ‐Responsive Polymers via the Combination of Aza‐Michael and Thiol‐Michael Reactions in One Pot

Aggregation-Induced Emission-Active Fluorescent Polymer: Multi-Targeted Sensor and ROS Scavenger

A multi-functional polymer with aggregation-induced emission (AIE)-active salicylaldehyde azine (SA) functionality and reactive oxygen species (ROS)-responsive thioether groups is readily prepared via thiol-ene click polymerization of SA derivative diacrylate monomer, poly(ethylene glycol) diacrylate, and 3,6-dioxa-1,8-octanedithiol. The obtained AIE-active polymer exhibited an unexpected strong emission in amide solvents compared to that in other common organic solvents that was dramatically decreased by adding a trace amount of water, suggesting that the polymer could be utilized as a water trace indicator in amide solvents. In the backbone, the PEG segments make the polymer well dispersed in water and the ROS-responsive thioether groups enable this polymer as a promising ROS scavenger, with embedded SA moieties as a fluorescent indicator for the hemolysis determination. Due to the ability of SA moieties to complex with Cu²⁺, this AIE polymer can also be utilized as a fluorescent sensor for selective Cu²⁺ detection in real-world water samples. Thus, this multi-functional polymer is anticipated to be well applied in biological and environmental applications.

Organocatalytic Michael Addition as a Method for Polyisobutylene Chain-End Functionalization

Functionalization of polyolefins, in particular polyisobutylene, remains a relatively unexplored application for the Michael reaction. This work evaluates the potential of polyisobutylene acrylate (PIBA) chain-end modification via organocatalyzed thiol-Michael and aza-Michael additions. A series of chain-end functional polyisobutylene oligomers are prepared using "click" reactions of thiols or amines to PIBA in the presence of 0.02 equivalents of organocatalyst. Reaction kinetics and chain-end transformations are monitored using NMR spectroscopy and the macromolecular products are characterized by size exclusion chromatography. Further potential of this synthetic strategy is illustrated by thiol-Michael addition of thiols formed in situ via nucleophilic thiolactone ring opening. The obtained results provide an efficient method for the preparation of functional polyisobutylene oligomers that can be utilized in a broad range of potential applications.