pH-responsive AIE-active Polyethylene-based Block Copolymers

Catalyst switch strategy enabled a single polymer with five different crystalline phases

Well-defined multicrystalline multiblock polymers are essential model polymers for advancing crystallization physics, phase separation, self-assembly, and improving the mechanical properties of materials. However, due to different chain properties and incompatible synthetic methodologies, multicrystalline multiblock polymers with more than two crystallites are rarely reported. Herein, by combining polyhomologation, ring-opening polymerization, and catalyst switch strategy, we synthesized a pentacrystalline pentablock quintopolymer, polyethylene-b-poly(ethylene oxide)-b-poly(ε-caprolactone)-b-poly(L-lactide)-b-polyglycolide (PE-b-PEO-b-PCL-b-PLLA-b-PGA). The fluoroalcohol-assisted catalyst switch enables the successful incorporation of a high melting point polyglycolide block into the complex multiblock structure. Solid-state nuclear magnetic resonance spectroscopy, X-ray diffraction, and differential scanning calorimetry revealed the existence of five different crystalline phases.

Multi Stimuli-Responsive Aggregation-Induced Emission Active Polymer Platform Based on Tetraphenylethylene-Appended Maleic Anhydride Terpolymers

Multi stimuli-responsive aggregation-induced emission (AIE) active polymers have great application prospects in high-tech innovations. Herein, three types of tetraphenylethylene (TPE)-containing monomers were synthesized and utilized in preparing TPE-appended maleic anhydride terpolymers. After hydrolysis, the produced TPE-appended maleic acid terpolymers have identical linear charge densities but different "primary" structures, which created widely varied microenvironments around the carboxylate and TPE groups. Benefiting from the synergistic interaction of the TPE moiety and the terpolymer conformation change, the TPE-appended maleic acid terpolymers exhibited fluorescence changes in response to multi stimuli, including pH, ionic strength, Ca²⁺, and bovine serum albumin. On both the "signaling" and the "stimuli acceptor" sides, the multi stimuli-responsive fluorescence behavior was influenced markedly by the terpolymer primary structure. The fundamental insights gained in the present work are important for developing an efficient and versatile stimuli-responsive AIE-active polymer platform for chemo-sensing, bioimaging, and so on.

Poly(amino acid)s-based star AIEgens for cell uptake with pH-response and chiral difference

Chiral aggregation-induced emission luminogens (AIEgens) are the new-generation chiral sensors that regulate chiral signals from the molecular level to the macroscopic assembly. Expanding applications of chiral AIEgens and in-depth understanding of their chiral recognition in biological systems are meaningful. Herein, two star chiral AIEgens, consisting of tetraphenylethene (TPE) as core and poly(N-acryloyl-L(D) valine) (PLV or PDV) as arms, were precisely synthesized via atom transfer radical polymerization (ATRP) technique and named TPE-PLV and TPE-PDV. They possessed typical AIE characteristics and exhibited an increase in concentration-dependent fluorescence intensity. The two AIEgens were pH-responsive and had strong AIE-related emission in acidic solution. Importantly, AIEgens can enter the living cells by ATP dependent endocytosis, then light them up. The interactions between the AIEgens and living human hepatocarcinoma (HepG2) cells revealed that the internalization process of TPE-PLV and TPE-PDV was both chiral-dependent and pH-responsive. This novel strategy for synthesizing poly(amino acid)s functionalized AIEgens could inspire the development of promising fluorescent materials with chirality.

Fabrication of reversible pH-responsive aggregation-induced emission luminogens assisted by a block copolymer via a dynamic covalent bond

Aggregated induced emission (AIE) molecules with stimuli-responsive properties have attracted increasing attention for many applications.