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Due to their unique physical and chemical features, dendronized polymers (DPs) have received increasing attention in various fields such as hierarchically structured materials, stimuli-responsive materials, catalysis, biosciences, optoelectronic devices, and so on. A large number of synthetic strategies also have been reported to prepare various functionalized DPs. Among these strategies, ring-opening metathesis polymerization (ROMP) and metathesis cyclopolymerization (MCP) using highly active and group-tolerant Ru-based catalysts as initiators were used as living and controlled techniques to fabricate well-defined DPs. The two efficient techniques present a promising prospect in the design and preparation of functional DPs. In this review, we focus on the synthesis of various classes of DPs by ROMP and MCP of dendritic macromonomers, and describe their characteristic structures and properties, as well as various functional applications. [ABSTRACT FROM AUTHOR]

Dendronized polymers (DPs) are an increasing field at the interfaces between organic chemistry, polymer synthesis, and materials science, and in particular DPs are expected to provide designed applications as nanoparticle (NP) sensors and catalysts. Herein, we report a new highly-branched amphiphilic dendronized diblock copolymer containing bulky hydrophilic triethylene glycol (TEG) and hydrophobic ferrocenyl (Fc) groups via the living and controlled ring-opening metathesis polymerization. The amphiphilicity drives the self-assembly of the resulting DP into spherical nanoscale micelles in water using THF or DMSO as cosolvents. AuNPs and AgNPs of various sizes depending on the presence of NaBH 4 are successfully prepared using the DP as stabilizers or reductants and used as excellent catalysts for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol by NaBH 4. The obtained AuNPs about 2.1 nm show TONs up to 25 000 and TOFs of 26 400 h−1 and remain stable and efficient for this catalysis after two months. Highly-branched amphiphilic ferrocenyl-containing dendronized diblock copolymer is prepared by ROMP and used as stabilizers or reductants to synthesize AuNPs and AgNPs for high-efficiency catalysis in 4-nitrophenol reduction. Image 1 • Ferrocenyl dendronized diblock copolymer is synthesized by ROMP. • Dendronized copolymer can self-assemble into nanoscale spherical micelles. • Dendronized copolymer can be used as reducing and stabilizing agents for AuNPs/AgNPs. • AuNPs and AgNPs show high catalytic activity for 4-nitrophenol reduction. • AuNPs and AgNPs show long-term stability and efficiency for catalysis. [ABSTRACT FROM AUTHOR]

Abstract: Novel well‐defined redox‐responsive Ferrocene (Fc)‐containing amphiphilic dendronized diblock copolymers are synthesized by the ring‐opening metathesis polymerization technique using Grubbs’ third‐generation olefin metathesis catalyst as the initiator. These dendronized block copolymers can self‐assemble into spherical micelles in aqueous solution. The size of self‐assembled micelles can be modulated by the composition (namely, the ratio of hydrophobic and hydrophilic segments) and concentration of the dendronized copolymers. The obtained micelles show reversible redox‐controlled self‐assembly behaviors using FeCl3 as oxidant and glutathione as reductant. Furthermore, the model molecule Rhodamine B is successfully loaded in these micelles, and the oxidation‐triggered controllable release is achieved by changing the type of oxidants (FeCl3 and H2O2) and their concentrations. This is the first example of redox‐responsive micelles self‐assembled by novel amphiphilic dendronized Fc‐containing block copolymers, and the present micelles are visualized to be potential candidates in many fields, especially in stimuli‐responsive drug delivery systems. [ABSTRACT FROM AUTHOR]

Gallol-functionalized polymers are highly desirable for their addressable functions in the fields of materials science, nanotechnology and biomedicine, owing to gallol's unique chemistry including excellent chelating properties to metals, easily oxidability and superior ability to bind proteins. Herein, we report the controlled synthesis of the first polynorbornene-based side-chain gallol-containing homopolymers and block copolymers with pendent triethylene glycol (TEG) moieties by the ring-opening metathesis polymerization (ROMP) using the 3rd generation Grubbs catalyst 1 as the initiator. We describe the direct synthetic route by the ROMP of a gallol-containing norbornene monomer, and the indirect approach via an acetoxyl protection/deprotection route. Among the tested metal ions of Fe 3+ , Mg 2+ , Cr 3+ and Al 3+ , Fe 3+ is the most effective metal ion to induce the gelation of the present gallol-containing polymers, and UV–visible spectroscopy indicates that bis-coordinated state dominates for the interaction between side-chain gallol groups and Fe 3+ ions in DMF. The gelation rate, interior structure, thermal and mechanical properties of the Fe 3+ -induced metallogels can be effectively tuned by changing the gallol/Fe 3+ molar ratio, polymeric molecular weight, and by introducing of organic TEG block. Furthermore, the oxidant-induced organogels were fabricated by adding the oxidant of NaIO 4 into the DMF solution of the gallol-containing polymers, and the gelation rate highly depends on the gallol/IO 4 − molar ratio and the introduction of TEG block. We are convinced that the effective synthesis of well-defined gallol-containing polymers, as illustrated by the present work, will pave the way for their functional applications as smart organogels, coatings, adhesives, capsules, etc. [ABSTRACT FROM AUTHOR]

Metal nanoparticle composite hydrogels (MNCHs) have attracted considerable attention in the catalytic field because hydrogels can provide appropriate microenvironment and enable catalysts to be conveniently separated and recycled. Here, a novel and well-defined gallol-functionalized hydrogel Gel-G was synthesized by ring-opening metathesis polymerization (ROMP). The resulting hydrogel Gel-G can be used as template to in situ prepare catalytically active gold nanoparticles hydrogel (AuNPs-Gel-G) and sliver nanoparticles hydrogel (AgNPs-Gel-G) without use of any external reductant based on the strong reducibility and coating property of the gallol moiety. The two MNCHs were well characterized by scanning electron microscope (SEM) and X-ray diffraction (XRD). Both AuNPs-Gel-G and AgNPs-Gel-G exhibited high catalytic activity for the 4-nitrophenol (4-NP) reduction to 4-aminophenol (4-AP), and can be easily separated and reused at least five times. [Display omitted] • Gallol-containing polymer hydrogels are synthesized by ROMP. • Gallol-containing polymer hydrogels are used for in situ fabrication of AuNPs and AgNPs composites. • AuNPs and AgNPs hydrogel composites exhibit good catalytic activity and reusability for 4-nitrophenol reduction. [ABSTRACT FROM AUTHOR]

Due to their high catalytic activity, gold nanoparticles (AuNPs) have been exploited as green and efficient catalysts in various chemical reactions, such as the oxidation of CO to CO 2 , aerobic oxidation of alcohols, C C coupling reactions and reduction reactions through transfer hydrogenation. Here, we report an efficient dendritic stabilizer for AuNPs. The dendritic stabilizer is a ferrocene-containing amphiphilic dendronized random copolymer that is synthesized by the ring-opening metathesis polymerization. And, the obtained amphiphilic copolymer can self-assemble into spherical micelles in aqueous solution, resulting in the formation of efficient nanoreactors for AuNPs in the 4-nitrophenol reduction to 4-aminophenol by NaBH 4. It is found that AuNPs obtained by using NaBH 4 as reductant have obviously smaller size and higher catalytic activity than those fabricated by using the ferrocene-based groups as reductant. The reusable experiment indicates that the small-sized AuNPs can be reused at least for fifteen times. We report ferrocene-containing amphiphilic dendronized random copolymer as efficient stabilizer for reusable gold nanoparticles in the reduction of 4-nitrophenol. Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract We present the controlled synthesis of the polynorbornene-based well-defined block copolymer PNFc- b -PNAd side-chain containing ferrocene (Fc) and adamantane (Ad) units by the ring-opening metathesis polymerization using the 3rd generation Grubbs catalyst. A polycationic amphiphilic block copolymer PNFcium- b -PNAd was then fabricated by the stoichiometric oxidation of Fc into ferricinium (Fcium) cations, and its redox-controlled reversible self-assembly behavior in water was demonstrated by SEM and DLS with glutathione as reductant and FeCl 3 as oxidant. By using benzocaine (BA) as model cargo, the loading ability of the cationic micelles formed by PNFcium- b -PNAd was investigated and confirmed, and the reduction of Fcium could lead to the rapid release of loaded payloads. A new supramolecular copolymer PNFc- b -PNAd@β-CD was further prepared by simply mixing PNFc- b -PNAd and β-cyclodextrin (β-CD) with equimolar quantity to Ad units, in which host-guest interactions were mainly observed between β-CD and pendant Ad. Owing to the formation of hydrophilic inclusion complexes, PNFc- b -PNAd@β-CD possesses amphiphilic property and exhibits redox-controlled self-assembly behavior in water, too. The oxidation-triggered release of loaded-BA from the supramolecular micelles was observed in a slow and durable way. The present novel redox-responsive micelles provide innovative examples of rational design for stimuli-responsive carriers by using Fc-containing polymers. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

The development of novel polymer carriers, which have well-defined structures and desired conjugative abiltiy to therapeutic agents, is still an urgent requirement in the field of polymer–drug conjugates (PDCs) used for stimuli-responsive drug delivery systems. Herein, we present the controlled synthesis of a novel amphiphilic polynorbornene-based block copolymer, side-chain containing hydrophobic functionalizable benzaldehyde groups and hydrophilic dentritic triethylene glycol (TEG) moieties, by the ring-opening metathesis polymerization (ROMP) using the 3rd generation Grubbs catalyst 1 as the initiator. The obtained copolymer can self-assemble into spherical micelles with the average size of 84 nm in water, and its remarkable ability as the polymer carrier to fabricate PDCs was fully confirmed by the efficient covalently Schiff-base linking of its side-chain benzaldehyde groups to amino groups of model drugs including O-benzylhydroxylamine (BHA), 1-hexadecanamine, tryptophan and benzocaine. Notably, torispherical micelles with the average size of 90 nm were also obtained by the self-assembly of the formed polymer-BHA conjugate, and the pH-triggered release of BHA molecules from the micelles was observed at acidic environments (for example, pH 4.0 and 2.5). Therefore, the present polynorbornene block copolymer is expected to find potential applications in the stimuli-responsive drug delivery systems as a promising polymer carrier to form PDCs via acid-responsive Schiff-base linkage with amino-containing drugs such as doxorubicin, daunorubicin, epirubicin and pirarubicin. [ABSTRACT FROM AUTHOR]