This article presents a brief overview of recent advances in azo-containing supramolecular systems. In literature, it has been shown that azo supramolecular polymers and their composite materials exhibit fast and intelligent responses to various external stimuli, such as temperature, pH change, redox reagents, ligands, coupling reagents, etc. In applications, these systems are widely used for molecular motors, shape memory, liquid crystal, solar thermal energy storage, signal transmission, intelligent encryption, and other purposes. Furthermore, these systems can function as key components for device upgrade processing. However, the design and rules of azo supramolecular polymers are still not supported by an exact theory. Information about the relationship between the spatial structure and behavior is lacking, and new supramolecular materials cannot be designed by adding functional moieties to known azo polymers. Based on the current research status, this review mainly summarizes the structural design principles as well as structures and applications of known azo supramolecules; meanwhile, it highlights the emerging development fields, recent advances, and prospects in fabricating self-assembling intelligent supramolecular systems with azo supramolecular polymers as responsive units. The goal of this review is to bring new inspiration to researchers who want to optimize the chemical structure, steric conformation, electrostatic environment, and specific molecular functionalization.

This contribution reports an efficient approach for preparing polycarbonate block terpolymers by immortal stepwise copolymerization of CO₂ with different epoxides in the presence of enol chain transfer, mediated by robust cobalt catalyst systems consisting of the fluorine substituted salenCo(III)NO₃ or biphenol-linker bimetallic Co(III) complex in conjunction with an ionic cocatalyst, PPNX (PPN = bis(triphenylphosphine)iminium, X = NO₃^– or 2,4-dinitrophenoxide). Various polycarbonate block terpolymers were obtained in perfectly unimodal distribution of their molecular weights with narrow polydispersity. They all possessed only one broad glass transition temperature, which could be adjusted by altering the length of different polycarbonate segments.

Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization (ROP) of lactones, including δ-valerolactone, ε-caprolactone, and δ-hexalactone. The catalysts are prepared by simply mixing tetra-n-butyl ammonium hydroxide and a (thio)urea at elevated temperature under vacuum, and used in cooperation with an alcoholic initiator. The performance of the catalyst is readily adjusted and optimized through variation of the (thio)urea precursor, catalyst composition, and reaction condition. Urea-derived catalysts are generally superior to thiourea-derived ones. Provided with proper N-substituents, the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification, even at high monomer conversion and/or substantially extended reaction time. In addition to acidity, structural symmetry of the urea also proves decisive for the catalytic activity, which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.

A series of nickel complexes {4a: [(2,6-iPr₂C₆H₃)N＝CHC₁₆H₁₂O]Ni(Me)(Py), 4b: [(2,6-iPr₂C₆H₂OCH₃)N＝CHC₁₆H₁₂O]Ni(Me)(Py), 4c: [(2,6-iPr₂C₆H₂Cl)N＝CHC₁₆H₁₂O]Ni(Me)(Py), and 4d: [(2,6-iPr₂C₆H₂CF₃)N＝CHC₁₆H₁₂O]Ni(Me)(Py)} based on β-ketiminato ligands bearing various electron-donating or electron-withdrawing substituents on the para-position of the aniline group were synthesized and unambiguously characterized. The X-ray crystallographic analysis showed that complexes 4b and 4d adopted a near-square-planar geometry, and the anilines bearing a para-OMe or ―CF₃ group were found to situate on the axial position of the metal center. All complexes exhibited high activities up to 1.25 × 10⁷–1.35 × 10⁷ g_PNB·mol_Ni^–1·h^–1 toward norbornene (NBE) addition polymerization (conversion > 91.2% in 2 min) under low loading of B(C₆F₅)₃ (B/Ni = 3) at 30 °C, affording polymers with high molecular weight up to 2.54 × 10⁶–3.18 × 10⁶. Different levels of decrease in catalytic activities could be observed for all catalysts as the reaction temperature increased; 4d bearing a strong electron-withdrawing ―CF₃ group showed the highest activity at 70 °C, while others exhibited notable decrease in catalytic activity with the raise in reaction temperature. Complexes 4a–4d showed remarkable tolerance to polar groups and could efficiently promote the copolymerization of NBE with its polar derivatives, including NBE bearing small acetate and hydroxyl group, as well as bulky oligomers, yielding copolymers with high functional NBE incorporations. Novel NBE copolymers with high functional comonomer incorporations and improved solubility were obtained in high yields.

Drug-resistance and drastic side effects are two major issues of traditional chemotherapy which may result in trail failure even death. Nanoparticle-mediated multidrug combination treatment has been proven to be a feasible strategy to overcome these challenges. In the present study, amphipathic block polymer of methoxyl poly(ethylene glycol)-poly(aspartyl(dibutylethylenediamine)-co-phenylalanine) (mPEG-P(Asp(DBA)-co-Phe)) was synthesized and self-assembled into pH-responsive polymeric vesicle. The vesicle was utilized to co-deliver cancer-associated epidermal growth factor (EGFR) inhibitor of afatinib and DNA-damaging chemotherapeutic doxorubicin hydrochloride (DOX) for enhanced non-small-cell lung cancer (NSCLC) therapy. As evaluated in vitro, the pH-responsive design of nanovesicle resulted in a rapid release of encapsulated drugs into tumor cells and caused enhanced cell apoptosis. In addition, in vivo therapeutic studies were conducted and the results evidenced that the co-delevery of DOX and afatinib using pH-sensitive nanovector was a promising strategy for NSCLC treatment.

In this work, poly(vinylidene fluoride) (PVDF) membranes with hydrophilicity as well as preeminent mechanical strength and dye removal efficiency were fabricated by blending with three dimensional hydroxyapatite nanoparticles (HAPNPs). Surface chemical composition and morphology of the prepared membranes were systematically investigated by ATR-FTIR, XPS, XRD, FESEM, and EDS mapping analyses. The results verified that a large number of HAPNPs were successfully embedded on the modified membrane cross-sections. Moreover, HAPNPs content in the casting solution is an important factor that could have profound influence on the structures and performances of PVDF/HAPNPs blend membranes. The optimal membrane M2 with 2 wt% HAPNPs exhibited excellent hydrophilicity, outstanding mechanical strength of 19.60 MPa, and high water flux of (2466 ± 31) L·m^–2·h^–1. The maximum static adsorption capacity of the optimal membrane was about 10.83 mg/g, which is 3.75 times that of the pristine PVDF membrane (2.89 mg/g). PVDF/HAPNPs membranes were not only utilized for static adsorption, but also applied to dynamic dye removal. The possible adsorption mechanism between Congo red (CR) and HAPNPs embedded on the blend membranes was firstly discussed in this work. HAPNPs interacted with CR via Lewis reaction, hydrogen bond interaction, as well as electrostatic attraction to achieve the adsorption effect. Herein, the PVDF/HAPNPs blend membranes with extraordinary hydrophilicity, mechanical strength, and dye removal efficiency possess tremendous potential for practical applications of wastewater treatment.

Owing to the excellent filtration performance and low energy cost, polymeric nanofibers microfiltration (MF) membranes have attracted increasing attentions. Poly(arylene sulfide sulfone) (PASS), as one of the structurally modified polymers based on poly(phenylene sulfide) (PPS), has been selected as the raw material to fabricate nanofibers MF membranes via electrospun techniques. The effects of PASS solution and the electrospinning processing parameters on the structural morphology of nanofibers were investigated in detail. The average diameter of PASS nanofibers was (296 ± 46) nm under the optimal condition: polymer concentration of 0.27 g·mL^–1 PASS/DMI, applied voltage of 20 kV, and speed of collector drum of 300 r·min^–1. And then the multi-layer PASS nanofibers MF membranes were fabricated from cold-pressing the optimized PASS nanofibers (as-prepared PASS nanofibers) membrane. The morphology, porosity, pore size, mechanical properties, and surface wettability of the multi-layer PASS nanofibers MF membranes could be tuned by the layers of as-prepared nanofibers membrane. The results demonstrated that the membrane with 6 layers (marked as PASS-6) exhibited the smallest porosity, smallest pore size, highest mechanical property, and best surface wettability. Meanwhile, the multi-layer PASS nanofibers MF membranes showed that the rejection ratio gradually increased, while the pure water flux decreased with increasing membranes thickness. The PASS-6 membrane exhibited large water flux of 747.76 L·m^–2·h^–1 and high separation efficiency of 99.9% to 0.2 μm particles, making it a promising candidate for microfilter.

A well-defined quadruple hydrogen bonding strategy involving dimerization of 2-ureido-4[1H]-pyrimidone (UPy) units is innovatively designed to prepare polyureas with high overall mechanical properties. Three polyureas containing different amounts of UPy units were synthesized by replacing a portion of isophorone diisocyanate (IPDI) with a UPy-derived diisocyanate. The formation of quadruple hydrogen bonds in hard segments via UPy dimers was confirmed by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). The mechanical properties of the polyureas were evaluated by uniaxial tensile testing. Compared to the polyurea without UPy units, remarkable improvements in Young’s modulus, tensile strength, and toughness were simultaneously achieved when UPy units were incorporated. The mechanism behind the strong strengthening effect rooted in the stronger intermolecular forces among hard segments brought by the quadruple hydrogen bonds, which were stronger than the inherent bidentate and monodentate hydrogen bonds among urea groups, and the slower soft segmental dynamics reaveled by both increased T_g and relaxation time of the soft segments. The mechanism behind the strong toughening effect was ascribed to more effective energy dissipation brought by the quadruple hydrogen bonds that served as stronger sacrificial bonds upon deformation. This work may offer new insight into the design of polyurea elastomers with comprehensively improved mechanical properties.

In this study, a novel waterborne polyurethane (WPU) with azobenzene-containing (azo-containing) pendant groups was synthesized by isophorone diisocyanate, long-chain diol of polycaprolactone, 2-ethyl-2-methyl-butanoic acid (2,2-dimethylolpropionic acid), 10-(4-(phenyldiazenyl)phenoxy)decyl-3-hydroxy-2-(hydroxymethyl)-2-methylpropanoate, and N,N-diethyl-ethanamine (triethylamine). Moreover, the influence of ultraviolet and visible (UV-Vis) light irradiation on the viscoelasticity of azo-containing WPU film in terms of the reversible trans-cis photoisomerization of azo-containing pendant groups was investigated by UV-Vis light spectroscopy, atomic force microscopy, and dynamic thermomechanical analysis. The results revealed that the adhesion of azo-containing WPU with single crystal silicon atomic force microscope probe was about 13 nN when irradiated by 450 nm Vis light for 60 s at 25 °C. Subsequently, the adhesion increased to 82 nN after irradiation with 365 nm UV light for 60 s at 25 °C. In addition, the azo-containing WPU presented a photo-induced reversible transition of tensile modulus and tanδ in the range from about 2 MPa to 22 MPa and 6000 to 0.35 with UV-Vis light cyclic irradiation for 120 s at 25 °C, respectively.

Polylactide (PLA), methyl methacrylate-butadiene-styrene copolymer (MBS), and poly(propylene carbonate) polyurethane (PPCU) were blended and subjected to blown film process. The rheological, mechanical, morphological, thermal, and crystalline properties of the PLA/MBS/PPCU ternary blends and the mechanical properties of the resulting films were studied. Results of mechanical test showed that PPCU and MBS could synergistically toughen PLA. The impact strength of 50/10/40 PLA/MBS/PPCU blend (74.7 kJ/m²) was about 7.5 times higher than that of the neat PLA (10.8 kJ/m²), and the elongation at break of 50/10/40 PLA/MBS/PPCU blend (276.5%) was higher by about 45 times that of PLA (6.2%). The tear strength of PLA/MBS/PPCU films was 20 kN/m higher than that of PLA, and the elongation at break (MD/TD) of 50/10/40 PLA/MBS/PPCU films was 271.1%/222.3%, whereas that of PLA was only 2.7%/3.0%. POM observations displayed that the density of spherulite nucleation increased and the size of crystalline particles decreased with the addition of MBS. With increasing PPCU content from 5% to 20%, the density of spherulite nucleation increased and the size of crystalline particles decreased continuously, but the nucleation density of spherulites was slightly lowered with increasing PPCU content from 30% to 40%. The PLA/MBS/PPCU films exhibited excellent mechanical properties, which expanded the application range of these biodegradable films.

The manufacturing process of poly(vinylidene fluoride) microporous films containing through flow channels and permeable to liquids has been elaborated. The process is based on polymer melt extrusion with subsequent stages of annealing, uniaxial extensions (" cold” and " hot” drawing), and thermal stabilization. The effect of orientation parameters (melt draw ratio and extension degrees) on overall porosity, permeability, morphology, and content of polar piezoactive β-phase in crystalline structure of the films was investigated by filtration porosimetry, sorptometry, scanning electron microscopy, X-ray scattering, and mechanical properties measurements. It is shown that the through pores were formed by a percolation mechanism. It is observed that permeability and the β-phase content increased with the growth of extension degree at the pore formation stages but the portion of β-crystallites decreased with increasing melt draw ratio at extrusion, which permitted to regulate the combination of through permeability and piezoactivity values by variation of the preparation process parameters.

The scaling relations among the mean end-to-end distance of polymer along the channel <R_||>, the polymer length N, and the effective diameter of channel D_e were investigated for flexible and semi-flexible polymer chains confined in long cylindrical channels. For the flexible polymer chain, scaling relation <R_||> ~ ND_e^–0.7 was found in the classic de Gennes regime at l_p²/b < D_e < R_g with l_p the persistence length, b the bond length, and R_g the radius of gyration of polymer. For the semi-flexible polymer, <R_||> ~ ND_e^–1 in the transition regime l_p < D_e < xl_p (x > 1) and <R_||> ~ D_e^–0.7 in the classic de Gennes regime at larger D_e > xl_p were observed. The simulation results revealed that the scaling relation in the transition regime was due to the rod-like behavior of the semi-flexible polymer in the small regime l_p < D_e < xl_p.

Interlocked-ring polymers, also known as polycatenanes, possess an interesting molecular architecture. These polymers are composed of many interlocked rings in a linear chain. The topological constrain between neighboring rings distinguishes the interlocked-ring polymer from its linear counterpart. Here we present extensive molecular dynamic simulations on the interlocked-ring polymers and analyze the static properties of the polymer. By applying external forces to the polymer, we also study the force-extension curves of the polymer, which provides rich information about the mechanical properties of the interlockedring polymers.

Computational strategies have been employed to investigate the influence of the nature of monomers and cross-linker in order to design three dimensional imprinted polymers with selective recognition sites for L-phenylalanine benzyl ester (L-PABE) molecule. Here, computational chemistry methods were applied to screen the molar quantity of functional monomers that interact with one mole of the template molecule. Effects of the nature of functional monomer, cross-linker, and molar ratio were determined computationally using density functional calculations with B3LYP functional and generic 6-31G basis set. Methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were used as the functional monomer and crosslinking agent, respectively. L-PABE imprinted polymer layered on multiwalled carbon nanotube (MWCNT) and conventional bulk MIP were synthesised and characterized as well. To investigate the influence of pre-organization of binding sites on the selectivity of L-PABE, respective non-imprinted polymers were also synthesised. MWCNT-MIPs and MIPs exhibited the highest adsorption capacity towards L-PABE. The synthesized polymers revealed characteristic adsorption features and selectivity towards L-PABE in comparison with those of its enantiomer analogues.