Synthesis of cationic hyperbranched multiarm copolymer and its application in self-reducing and stabilizing gold nanoparticles

Polyethylenimine as a Versatile Simultaneous Reducing and Stabilizing Agent Enabling One-Pot Synthesis of Transition-Metal Nanoparticles: Fundamental Aspects and Practical Implications

The large surface area of metallic nanoparticles provides them with particular optical, chemical, and biological properties, accordingly enabling their use in a wide array of applications. In this regard, facile and fast synthetic approaches are desirable for ready-to-use functional materials. Following early investigations focused on the direct synthesis of polymer-coated gold nanoparticles, we herein demonstrate that such a strategy can be used to manufacture different types of d-block transition-metal nanoparticles via a one-pot method in aqueous media and mild temperature conditions. Gold (Au3+), palladium (Pd2+), and silver (Ag+) ions could be reduced using only polyethylenimine (PEI) or PEI derivatives acting simultaneously as a reducing and stabilizing agent and without the aid of any other external agent. The process gave rise, for instance, to Pd urchin-like nanostructures with a large surface area which confers to them outstanding catalytic performance compared to AuNPs and AgNPs produced using the same strategy. The polymer-stabilized AgNPs were demonstrated to be biocide against a variety of microorganisms, although AuNPs and PdNPs do not hold such an attribute at least in the probed concentration range. These findings may provide significant advances toward the practical, facile, and ready-to-use manufacturing of transition-metal nanoparticles for a myriad of applications.

Antifouling and antimicrobial polyethersulfone/hyperbranched polyester-amide/Ag composite

This study provided a facile approach for the development of antifouling and antibacterial polyethersulfone (PES) composite film. Mainly, hyperbranched polyester-amide (PESAM) was used as both the reducing and capping agent for the in situ formation of AgNPs. The nanoparticles were intensively investigated using Fourier transform infrared spectroscopy (FTIR), ultra-violet spectroscopy (UV-vis), scanning and transmission electron microscopy (SEM & TEM) and X-ray diffraction (XRD). AgNPs were narrowly distributed with an average particle size of about 6 nm. PESAM was mixed with PES to realize free-standing film using the phase inversion method. The inclusion of PESAM in the composite film significantly improved hydrophilicity as confirmed by the contact angle measurements. Furthermore, SEM and EDX investigations confirmed that PESAM induced the in situ formation of AgNPs not only on the film surface but also inside its macro-voids. The composite film (PES/PESAM/Ag) displayed significant antibacterial potential against Gram positive and Gram negative bacteria. Overall, the described method paves the way towards development of advanced PES composite films with antimicrobial properties for broad application areas that include desalination membranes or active packaging materials.

The influence of amine structures on the stability and catalytic activity of gold nanoparticles stabilized by amine-modified hyperbranched polymers

Amine-modified amphiphilic hyperbranched polymers (MePEG-H104-Nx) were prepared from hyperbranched 2,2-bis(methylol)propionic acid polyester (H104) by decoration with polyethylene glycol monomethyl ether (MePEG) and different classes of oligo(ethylenimine)s. By using the MePEG-H104-Nx polymers as stabilizers, gold nanoparticles (AuNPs) were prepared in an aqueous medium by the reduction of HAuCl₄ with NaBH₄. The AuNPs were sphere-like with diameters of 2-4 nm, which were dependent on the structure of the amines. Further, the catalytic activity of these AuNPs was evaluated by monitoring the reduction reaction of 4-nitrophenol by sodium borohydride. The results demonstrate that the longer chain length and the branched structure of the amine moieties are beneficial for the stability and catalytic activity of the AuNPs. The AuNPs stabilized by MePEG-H104-N4 and MePEG-H104-Nb3 showed high catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol.

Host–guest binding motifs based on hyperbranched polymers

Host–guest systems based on hyperbranched polymers together with their unique properties and various applications have been summarized.

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.