Imidazole-based Cu(i)-catalyzed click polymerization of diazides and diynes under mild conditions

An efficient imidazole-based Cu(i)-catalyzed azide–alkyne click polymerization under mild reaction conditions was developed.

Facile topological transformation of ABA triblock copolymers into multisite, single-chain-folding and branched multiblock copolymers via sequential click coupling and anthracene chemistry

Telechelic PtBA-b-PSt-b-PtBA copolymers were designed to achieve on-demand topological transformation into multisite, single-chain-folding and branched multiblock copolymers via click/click-like reactions.

Library of Derivatizable Multiblock Copolymers by Nucleophilic Substitution Polymerization and Targeting Specific Properties

Multiblock copolymers (MBCs) are fascinating in the field of biology-polymer chemistry interfaces. Synthesizing libraries of MBCs with tailor-made functionality is challenging as it involves multiple steps. Herein, a simple synthesis, analogous to polyurethane/Michael addition reactions, has been introduced to obtain a library of derivatizable MBCs. Nucleophilic substitution polymerization (S_NP) of poly(ε-caprolactone) and poly(ethylene glycol) blocks containing activated halide termini by primary mono/di/coamines or clickable amines provides functional MBCs. The structure of amines directs the properties of the MBCs. The self-assembly of small molecular weight primary diamine-based MBCs shows controlled release of hydrophobic model guest molecules and therapeutics. The primary diamine (no dangling chain) helps to form MBC micelles having a relatively tight core with a low diffusion property. Antimicrobial property in the MBCs has been introduced by separating the cationic centers from the lipophilic groups using a coamine as a nucleophilic agent and a small molecular weight dihalide as a chain extender. Clickable MBCs were synthesized by changing the structure of the nucleophile to obtain degradable amphiphilic conetworks and hydrogels. Varieties of macromolecular entities could be obtained by switching the nucleophilic agent and introducing a small molecular weight chain extender. This synthesis approach provides an opportunity to tune the chemical functionality, topological structure, and biological properties of macromolecular entities.

Ferrocene-based hyperbranched poly(phenyltriazolylcarboxylate)s: synthesis by phenylpropiolate-azide polycycloaddition and use as precursors to nanostructured magnetoceramics

Ferrocene-based hb-PPTCs with redox activity are readily prepared by the catalyst-free phenylpropiolate-azide polycycloaddition. They could be used as precursors to produce nanostructured magnetoceramics upon pyrolysis.

Progress on Catalytic Systems Used in Click Polymerization

Click polymerization, a powerful synthetic technique to construct polymers with unique structures and advanced functions, is of crucial importance in the areas of polymer and material sciences. A variety of click polymerizations such as azide-alkyne, thiol-yne, amino-yne, and hydroxyl-yne reactions have been established, wherein the catalytic systems play an indispensable role in realizing these highly practical reactions based on triple-bond building blocks, as they directly influence the efficiencies of the click polymerizations and the performances of the resultant polymers. The vital employment of catalysts is reviewed and their developments from innovative discoveries to the eminent position are outlined. Moreover, the challenges and perspectives in this area are also briefly discussed.

Recent advances in alkyne-based click polymerizations

The recent progress in alkyne-based click polymerizations and their application in the preparation of new functional polymers are summarized. The challenges and opportunities in this area are also briefly discussed.

Nano-Star-Shaped Polymers for Drug Delivery Applications

With the advancement of polymer engineering, complex star-shaped polymer architectures can be synthesized with ease, bringing about a host of unique properties and applications. The polymer arms can be functionalized with different chemical groups to fine-tune the response behavior or be endowed with targeting ligands or stimuli responsive moieties to control its physicochemical behavior and self-organization in solution. Rheological properties of these solutions can be modulated, which also facilitates the control of the diffusion of the drug from these star-based nanocarriers. However, these star-shaped polymers designed for drug delivery are still in a very early stage of development. Due to the sheer diversity of macromolecules that can take on the star architectures and the various combinations of functional groups that can be cross-linked together, there remain many structure-property relationships which have yet to be fully established. This review aims to provide an introductory perspective on the basic synthetic methods of star-shaped polymers, the properties which can be controlled by the unique architecture, and also recent advances in drug delivery applications related to these star candidates.

The use of azide-alkyne click chemistry in recent syntheses and applications of polytriazole-based nanostructured polymers

The rapid development of efficient organic click coupling reactions has significantly facilitated the construction of synthetic polymers with sophisticated branched nanostructures. This Feature Article summarizes the recent progress in the application of efficient copper-catalyzed and copper-free azide-alkyne cycloaddition (CuAAC and CuFAAC) reactions in the syntheses of dendrimers, hyperbranched polymers, star polymers, graft polymers, molecular brushes, and cyclic graft polymers. Literature reports on the interesting properties and functions of these polytriazole-based nanostructured polymers are also discussed to illustrate their potential applications as self-healing polymers, adhesives, polymer catalysts, opto-electronic polymer materials and polymer carriers for drug and imaging molecules.

Poly(ethylene glycol) conjugated poly(lactide)-based polyelectrolytes: synthesis and formation of stable self-assemblies induced by stereocomplexation

A series of pH-responsive amphiphilic poly(N,N-dimethylaminoethyl methacrylate)-block-poly(D-lactic acid)-block-poly(N,N-dimethylaminoethyl methacrylate) conjugated with poly(ethylene glycol) (D-PDLA-D@PEG) and D-PLLA-D@PEG copolymers were synthesized using a combination of ring-opening polymerization and atom-transfer radical polymerization followed by sequential quaternization of PDMAEMA chains and azide-alkyne click reaction with alkyne-end PEG. Gel permeation chromatography, nuclear magnetic resonance, and Fourier transform infrared spectroscopy results demonstrate the successful synthesis of the copolymers, and the conjugated PEG percentages in the copolymers can be tuned by the feeding ratios in the quaternization reaction. Conjugating PEG onto the PDMAEMA segments also successfully facilitated the D-PDLA-D@PEG, D-PLLA-D@PEG, and its corresponding 1:1 D/L mixtures to be dissolved directly in aqueous solution at the desired concentration range without using any organic solvents unlike the copolymers without PEG conjugation (D-PDLA-D and D-PLLA-D). We demonstrate control over micellar size, charge, and stability via three different preparation pathways, i.e., solution pH, percentages of PEG conjugation in the copolymers, and formation of PLA stereocomplex in micellar core. Static and dynamic light scattering studies demonstrate that the size of the core-shell micelles increases when the solution pH is reduced due to the protonation of the PDMAEMA segments that caused the osmotic pressure within the micelle to increase until the micelles reached a maximum size. It is interesting to note that the micelles formed by 1:1 D/L mixtures have larger swelling ratios as well as aggregation number and hydrodynamic radius that do not change significantly with pH and dilution, respectively, as compared to micelles formed from individual D or L forms of the copolymers. The enhanced stability of the pH-responsive micelles prepared by direct dissolution of the 1:1 D/L mixtures of the PEG conjugated PLA-based polyelectrolytes in aqueous medium is attributed to the stereocomplex formation between PLLA and PDLA in the micellar core as confirmed by wide-angle X-ray scattering measurements.

Hyperbranched poly(triazole) with thermal and metal ion dual stimuli-responsiveness

Hyperbranched poly(triazole) bearing oligo(ethylene glycol) terminal groups is dual stimuli-responsive to thermal conditions and metal ions and is capable for the selective absorption of Ag⁺ ion on tuning temperature.

Synthesis, characterization, micellization and application of novel multiblock copolymers with the same compositions but different linkages

Several novel multiblock copolymers, (PEO-b-PS-b-PEO-Diyne)_s, [PEO-b-PS-b-PEO-(OH)₄]_s and (PEO-b-PS-b-PEO-Acetal)_s, with the same compositions but different linkages were constructed, and their micellization and application were studied.

The electrophilic effect of thiol groups on thiol–yne thermal click polymerization for hyperbranched polythioether

The significant effect of the electrophilicity of the thiol groups on thiol–yne click polymerization was found and well demonstrated.

Hyperbranched polymers: advances from synthesis to applications

This review summarizes the advances in hyperbranched polymers from the viewpoint of structure, click synthesis and functionalization towards their applications in the last decade.

Synthesis of 1,5-regioregular polytriazoles by efficient NMe4OH-mediated azide–alkyne click polymerization

The efficient and regioselective NMe₄OH-mediated aromatic azide and alkyne click polymerization to generate 1,5-regioregular polytriazoles was successfully established.

A recyclable and reusable supported Cu(I) catalyzed azide-alkyne click polymerization

The azide-alkyne click polymerization (AACP) has emerged as a powerful tool for the synthesis of functional polytriazoles. While, for the Cu(I)-catalyzed AACP, the removal of the catalytic Cu(I) species from the resulting polytriazoles is difficult, and the research on the recyclability and reusability of the catalyst remains intact. Herein, we reported the first example of using recyclable and reusable supported Cu(I) catalyst of CuI@A-21 for the AACP. CuI@A-21 could not only efficiently catalyze the AACP but also be reused for at least 4 cycles. Moreover, pronounced reduction of copper residues in the products was achieved. Apart from being a green and cost-effective polymer synthesis strategy, this method will also broaden the application of AACP in material and biological sciences and provide guidelines for other polymerizations with metal catalysts.