Intrachain Folding and Interchain Association of Hyperbranched Chains with Long Uniform Subchains Made of Amphiphilic Diblock Copolymers

Ethylcellulose Colloids Incubated in Dilute Solution

This study revealed, for the first time, that dilute solutions made of a representative series of commercial ethylcellulose (EC; molecular weights 77-305 kDa, provided by the manufacturer) and four distinct organic solvents (α-terpineol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate (TPIB), tetrahydrofuran (THF), and benzene) can be used to foster stabilized, nearly monodisperse, nanoscale (pure) polymer colloid, with no isolated chains present. Using combined light-scattering (dynamic light scattering, static form factor, and Zimm/Berry plots) and intrinsic viscosity (Tanglertpaibul-Rao, Huggins, and Kraemer plots) analyses, the structural features of colloidal EC aggregates, ρ = ⟨R_g⟩/⟨R_h⟩ = 0.67-0.83, were first shown to be described rather well by the theory on colloidal spheres (⟨R_g⟩ and ⟨R_h⟩ being the mean radius of gyration and the hydrodynamic radius, respectively). An empirical scaling law relating the intrinsic viscosity to the mean colloid size can thus be established: [η]_H = (1.7 ± 0.2) ×10^-3 ⟨R_h⟩^(2.1±0.3) ([η]_H and ⟨R_h⟩ in units of mL/g and nm, respectively), which may be contrasted with the Zimm model for isolated Gaussian coils, [η]_H ∼ ⟨R_h⟩¹, and the Einstein equation for isolated solid spheres, [η]_H ∼ ⟨R_h⟩⁰. Optical microscopy images of thin films cast from different EC solutions clearly revealed the abundance of micron EC agglomerates, contrary to the uniform thin-film morphology produced from a dilute polystyrene solution, which serves as a reference solution composed of isolated chains. These observations point to new features and applications of EC dispersions.

Long-subchain Janus-dendritic copolymers from locally confined click reaction and generation-dependent micro-phase separation

Long-subchain Janus-dendritic copolymers composed of PSt and PtBA half-dendrons, up to the third generation, were prepared under alternating chemical and local confinement. All the Janus-dendritic copolymers exhibited generation-dependent microphase separation.

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.

Reversible Self-Assembly of Backbone-Thermoresponsive Long Chain Hyperbranched Poly(N-Isopropyl Acrylamide)

In this paper, we mainly described the reversible self-assembly of a backbone-thermoresponsive, long-chain, hyperbranched poly(N-isopropyl acrylamide) (LCHBPNIPAM) in aqueous solution. Here, we revealed a reversible self-assembly behavior of LCHBPNIPAM aqueous solution derived from temperature. By controlling the temperature of LCHBPNIPAM aqueous solution, we tune the morphology of the LCHBPNIPAM self-assemblies. When the solution temperature increased from the room temperature to the lower critical solution temperature of PNIPAM segments, LCHBPNIPAM self-assembled from multi-compartment vesicles into solid micelles. The morphology of LCHBPNIPAM self-assemblies changed from solid micelles to multi-compartment vesicles again when the temperature decreased back to the room temperature. The size presented, at first, an increase, and then a decrease, tendency in the heating-cooling process. The above thermally-triggered self-assembly behavior of LCHBPNIPAM aqueous solution was investigated by dynamic/static light scattering, transmission electron microscopy, atomic force microscopy, fluorescence spectroscopy, ¹H nuclear magnetic resonance in D₂O, and attenuated total reflectance Fourier transform infrared spectroscopy. These results indicated that LCHBPNIPAM aqueous solution presents a reversible self-assembly process. The controlled release behaviors of doxorubicin from the vesicles and micelles formed by LCHBPNIPAM further proved the feasibility of these self-assemblies as the stimulus-responsive drug delivery system.

Janus long-chain hyperbranched copolymers of PSt and POEGMA from a self-assembly mediated click reaction

A Janus hyperbranched POEGMA/PSt copolymer with long sub-chains was prepared through a self-assembly mediated click reaction in selective solvents.

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.