Macromolecular Rapid Communications最新文献

Due to the abundant hydrogen bond networks, high crystallinity, and high molecular weight of chitin, it is difficult to dissolve chitin in most solvents. Meanwhile, most of the existing solvent systems have the disadvantages of high toxicity, low solubility, and high cost. Therefore, the efficient and rapid dissolution of chitin using green solvents is urgently needed. In this work, ternary DES with amino acids, urea, and 1,8-Diazabicyclo[5.4.0]undec-7-ene (DBU) is prepared at first. Then chitin can be dissolved fastly with the assistance of a microwave. Compared with the conventional heating process (110 °C, 6-8 h), the microwave process can be shortened to only 3-10 min. The successful dissolution of chitin is verified by means of fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), rheology studies, and optical light microscope, and the dissolution mechanism contributed to the synergistic destroying of the hydrogen bond networks of chitin by amino acids and DBU. The DES solvent can be well recovered with the remaining of its dissolving ability to chitin.

Controlled branched structures remain a key synthetic limitation for monomeric tissue adhesives because their on-site polymerization that enables adhesion formation requires rapid kinetics, high conversion, and straightforward setup. In this context, site-specific branching initiation by using evolmers is potentially effective for structural control; however, the efficiency and kinetics in current reaction setups persists to be a major challenge. In this paper, an evolmer induces a controlled branching polymerization of cyanoacrylate amid the high monomer reactivity useful in rapid adhesion. The contrasting reactivities between the vinyl and the initiating groups in the evolmer molecule generate a kinetic pathway that favors a control-enabling branching mechanism. Through density functional theory calculations, the reaction pathway toward branching is shown to kinetically favor site-specific initiation by six orders of magnitude than the route toward non-specificity. Reaction monitoring confirms the branching polymerization after the polymerization with the evolmer forms a more compact structure than the linear counterpart. Control of branching density is demonstrated in rapid polymerizations within minutes and in polymerizations completed in an instant. These results provide a template for achieving site-specific branching initiation during adhesion formation and, broadly, where conditions for kinetic control are necessary.

In the present study, low molecular weight cyclic polyglycidol is used as a macroinitiator for hypergrafting glycidol and producing cyclic graft hyperbranched polyglycerol (cPG-g-hbPG) in the molecular weight range of 10³-10⁶ g mol^-1. Linear graft hyperbranched polyglycerol (linPG-g-hbPG) and hyperbranched polyglycerol (hbPG) are prepared as reference samples. This creates a family of hbPG structures with cyclic, linear, and star cores, allowing to evaluate their properties in solution and in bulk. The morphology study of the high molecular weight structures using atomic force microscopy revealed a spherical shape for cPG-g-hbPG and hbPG, and a cylindrical shape for linPG-g-hbPG in the nanometric range. Small angle X-ray scattering confirmed the compact particle-like structure of this family of hbPG architectures. Interestingly, the glass transition temperature showed a structure dependence, with cPG-g-hbPG having the highest values and hbPG having the lowest values for the same molecular weight. This study is a step forward in the generation of water-soluble polymers with tailored structure and functionality for advanced applications.

In the quest for powerful, safe, and storable photoinduced-electron transfer (PET) donors, the attention is turned to the α-trihalomethylated amine moiety that is not studied in the context of PET-reductants. The thermal and photophysical properties of α-trifluoromethylated quinolines are thus studied and their reducing abilities evaluated as initiators of polymerization reactions. Polymers of high molecular weights are obtained through a radical polymerization process and the PET-donor can be stored within the monomer for several months without losing its efficiency. Mechanistic investigations, combining spectroscopic analysis and theoretical calculations, confirm the mode of activation of these electron donors and the generation of radical intermediates through single electron transfer.

Polymer colloidal crystals (PCCs) have been widely explored as acoustic and optical metamaterials and as templates for nanolithography. However, fabrication impurities and fragility of the self-assembled structures are critical bottlenecks for the device's efficiency and applications. We have demonstrated that temperature-assisted pressure [ $T,p]$ annealing results in the mechanical strengthening of PCCs, which improves with the annealing temperature. Here, the enhancement of elastic properties and morphological features of self-assembled PCC's is evaluated using Brillouin light scattering and scanning electron microscopy. The pressure-induced effects on the vibrational modes of PCCs are also illustrated at temperatures well below the polymer glass transition. While the PCCs colloid constituents display reversibility, the PCC material is strongly irreversible in the performed thermodynamic cycle. The effective elastic modulus enhances from 0.7 GPa for the pristine sample to 0.8 GPa, solely by pressure annealing at room temperature. [ $T,p]$ annealing at higher temperatures leads to a maximum effective elastic modulus of 1.7 GPa, more than twice the value in the pristine sample. Above a cross-over pressure, $p_c(\approx$ 725 bar at 348 K), the PCCs respond elastically and, hence, reversibly to pressure changes.

Herein, a photoinduced method is introduced for the synthesis of highly cross-linked and uniform polymer microspheres by atom transfer radical polymerization (ATRP) at room temperature and in the absence of stabilizers or surfactants. Uniform particles are obtained at monomer concentrations as high as 10% (by volume), with polymers being exempt from contamination by residual transition metal catalysts, thereby overcoming the two major longstanding problems associated with thermally initiated ATRP-mediated precipitation polymerization. Moreover, the obtained particles have also immobilized ATRP initiators on their surface, which directly enables the controlled growth of densely grafted polymer layers with adjustable thickness and a well-defined chemical composition. The method is then employed successfully for the synthesis of molecularly imprinted polymer microspheres.

Surface proton hopping conduction (SPHC) mechanisms is an important proton conduction mechanism in conventional polymer electrolytes, along with the Grotthuss and vehicle mechanisms. Due to the small diffusion coefficient of protons in the SPHC mechanism, few studies have focused on the SPHC mechanism. Recently, it has been found that a dense alignment of SO₃ ^- groups significantly lowers the activation energy in the SPHC mechanism, enabling fast proton conduction. In this study, a series of polymerizable amphiphilic-zwitterions is prepared, forming bicontinuous cubic liquid-crystalline assemblies with gyroid symmetry in the presence of suitable amounts of bis(trifluoromethanesulfonyl) imide (HTf₂N) and water. In situ polymerization of these compounds yields gyroid-nanostructured polymer films, as confirmed by synchrotron small-angle X-ray scattering experiments. The high proton conductivity of the films on the order of 10^-2 S cm^-1 at 40 °C and relative humidity of 90% is based solely on the SPHC mechanism.

The pursuit of molecules capable of binding to wood lignin is pivotal for advancing lignin degradation technology, particularly when combined with lignin degradation catalysts. In this study, synthetic polymers bearing histidine moieties, demonstrating remarkable affinity for wood lignin are reported. These polymers, featuring varying degrees of histidine substitution in the form of histidine methyl esters, are synthesized through controlled radical polymerization of an activated ester-bearing monomer, employing a fluorescein-labeled chain transfer agent and subsequent postpolymerization amidation with histidine methyl ester. The binding properties of these histidine-bearing polymers with milled wood lignin under aqueous conditions are investigated. Qualitative assessment of lignin-binding capabilities involve spectroscopic analysis of changes in absorbance of visible light and fluorescence intensity. Furthermore, quantitative evaluation is conducted through surface plasmon resonance measurements to determine the binding parameters of the polymers with wood lignin. Notably, polymers with higher histidine substitution exhibit enhanced binding affinity compared to those with lower histidine substitution levels.

This review explores core-shell scaffolds in bone tissue engineering, highlighting their osteoconductive and osteoinductive properties critical for bone growth and regeneration. Key design factors include material selection, porosity, mechanical strength, biodegradation kinetics, and bioactivity. Electrospun core-shell nanofibrous scaffolds demonstrate potential in delivering therapeutic agents and enhancing bone regeneration. Critical characterization techniques include structural, surface, chemical composition, mechanical, and degradation analyses. Scaling up production poses challenges, addressed by innovative electrospinning techniques. Future research focuses on regulatory and commercial considerations, while exploring advanced materials and fabrication methods to optimize scaffold performance for improved clinical outcomes.

Branch-connected dimerized acceptors can take full advantages of four end units in enhancing molecular packing comparing to that of terminal-connected ones, thus potentially reaching the best balance between stability and power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, two branch-connected dimerized acceptors, namely D1 and D2, are developed by employing bithiophene and difluorinated bithiophene as linker groups, respectively. Induced by the fluorine atoms on linker group, D2 affords a larger molar extinction coefficient, more importantly, the optimized nanoscale film morphology and superior charge transport behavior comparing to D1. Consequently, D2-based binary OSCs render a good PCE of 16.66%, outperforming that of 15.08% for D1-based ones. This work highlights the great significance of linker group screening in designing high-performance branch-connected dimerized acceptors.