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Drug carriers and visual tracking play an important role in accurate and efficient drug delivery systems for targeted drug therapy. Polymerization‐induced self‐assembly (PISA), a powerful strategy for the fabrication of stimuli‐responsive polymeric nanoparticles has been a focus over the past decade due to its promising applications in biomedical fields such as targeted drug delivery and fluorescent nanoprobes used for tumor imaging. Herein, hypoxia‐responsive near‐infrared (NIR) fluorescent nanoprobes of amphiphilic block copolymers (PPEGMA14‐ADP‐Azo‐PBzMAx) are reported, the first example synthesized by RAFT‐mediated PISA strategy in situ to realize synchronous drug release and cell imaging. First, a series of nanoparticles with different morphologies and sizes, including spheres and vesicles, are synthesized by the PISA strategy using PPEGMA14‐ADP‐Azo‐CDPA as macro‐RAFT agents link with near‐infrared Aza‐BODIPY fluorogen and azobenzene groups. Hypoxia‐triggered dissociation of the nanoprobes and NIR fluorescence emission is then observed because of the cleavage of azo bonds. Meanwhile, the in situ DOX‐loaded nanoprobes by the PISA demonstrate synchronous drug release and NIR fluorescence enhancement against mouse colon cancer cells (CT26) under hypoxia (1% O2) compared with under normoxia (16% O2). [ABSTRACT FROM AUTHOR]

The self‐assembly of amphiphilic oligomers/polymers is a versatile and promising approach for creating nonspherical polymeric nanoparticles. Discrete amphiphilic oligomers/polymers with molecularly defined structures are ideal candidates for fabricating smart nanoparticles and for achieving a deeper understanding of structure‐controlled self‐assembly. Herein, discrete and disperse amphiphilic homopolymers of PAZOnTEG2n, with hydrophobic azobenzene are designed and synthesized as the main chains tethered with hydrophilic tetraethylene glycol monomethyl ether (TEG) units, to accurately investigate the impact of dispersity on their self‐assembly in solution. The discrete‐PAZO8TEG16 in DMF/water and in THF/water results in the formation of 2D lamellae, while the dispersed counterpart prefers to self‐assemble into spherical micelles. The significant difference is due to their distinction between interior structures of assembly. Furthermore, photoisomerization of azobenzene triggers dissociation/reassembly for discrete polymeric nanoparticles but no obvious change for the dispersed counterparts under irradiation with UV/vis light. This work reveals the influence of dispersity on the self‐assembly of amphiphilic polymers and stimuli‐responsive properties of their nanomaterials, which is desirable for universal applicability in fabricating smart 2D lamellas. [ABSTRACT FROM AUTHOR]

It is well known that macromolecular structure, including composition, topology and sequence, significantly determines the properties of conjugated polymers/oligomers. To accurately understand the structure‐induced properties, discrete oligomers/polymers with molecularly defined structures are the ideal model because they provide distinct nonstatistical results. Herein, a series of discrete conjugated fluorene‐azo oligomers with different positions of the azobenzene units along the main chain (i.e., sequence) are efficiently prepared based on CuAAC "click" chemistry via a stepwise chain‐growth strategy. Position‐dependent behavior has an evident impact on the properties of oligomers, such as thermal properties, optical properties and photoresponsive behavior in both solution and thin film states. In addition, the fluorene‐azo oligomers show less photodegradation of 9,9‐dioctyl‐fluorene in the solid‐state than oligofluorene during UV light irradiation; however, position‐dependent photodegradation is found in solution. Optimized configurations and UV–vis absorption spectra of fluorene‐azo oligomers are calculated by density functional theory. Experimental results and theoretical analysis indicate that the location of azobenzene can play a dominant role in determining the properties of fluorene‐azo oligomers resulting from sequence‐mandated conformational changes. Undoubtedly, this work can provide deeper insight into the structure–property relationships based on precisely sequence‐defined polymer structures. [ABSTRACT FROM AUTHOR]

Since Hermann Staudinger coined the term "macromolecule" in the 1920s, one century of development of polymers in both academia and industry has had an overwhelming impact on human society. Furthermore, polymer chemists have made tremendous efforts to regulate polymer sequences, i.e., precisely arrange monomer units along the polymer chains to mimic DNA. To build a sustainable future of polymer manufacturing, bio-based monomers and eco-friendly degradable polymers have attracted immense interest in polymer communities. [Extracted from the article]

The application of selenol-X chemistry in nucleophilic substitution and Se-Michael addition reactions for polymer chain end modification is presented. Selenol-labeled polystyrene can easily react with alkyl halides, methyl methacrylate, methyl acrylate, pentafluorostyrene, etc. The mild conditions make it attractive for the synthesis of macromonomers. The resulting polymers are analyzed and characterized by UV, size-exclusion chromatography (SEC), NMR, and matrix assisted laser desorption/ionization time of flight mass spectroscopy. [ABSTRACT FROM AUTHOR]

A novel Janus compound containing azo-based thermal initiator and bromo-based atom transfer radical polymerization (ATRP) initiator group is synthesized. Such compound can be applied in the living radical polymerization of alkyl methacrylate monomers, such as methyl methacrylate, tert-butyl methacrylate, and 2-( N, N-dimethylamino) ethyl methacrylate. Polymers with controlled molecular weights and narrow molecular weight distributions are obtained. The structure of polymers is identified by 1H NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight mass spectrum. A modified initiator for continuous activator regeneration ATRP mechanism is proposed according to the polymerization behavior, hydrolysis of chain backbone, and end group identification. [ABSTRACT FROM AUTHOR]

Typically, intramolecular cyclization reactions need to be conducted at high dilution to avoid interchain coupling, which leads to the production of cyclic polymer at an extremely low output. Herein, a high-efficiency Cu-catalyzed azide/alkyne cycloaddition 'click' synthesis of cyclic polystyrene (PS) and cyclic poly (methyl methacrylate) (PMMA) is reported via a circulatory technique of evaporation-condensation-extraction-inflow strategy by the utilization of elaborately designed equipment. High-output cyclic PS (one batch, 0.71 g cyclic polymer from 1.0 g linear polymer loading) and cyclic PMMA (one batch, 0.62 g cyclic PMMA from 1.0 g linear polymer loading) are achieved. This promising preparation should be beneficial to the large-scale application and research of cyclic polymers. [ABSTRACT FROM AUTHOR]