Macromolecular Rapid Communications最新文献

Fiber-reinforced composites (FRCs) possess a remarkable strength-to-weight ratio, making them ideal light-weighing alternative materials of metals used in automotive, aerospace, and outdoor equipment applications, but their recycling is challenging. Chemically recyclable thermoset polymers can enable fiber recovery and reuse; however, challenges remain in the separation and purification of depolymerized small molecules for efficient polymer recycling. To this end, a series of liquid resins for chemically recyclable polymer networks is designed based on phthalic anhydride, a widely produced and inexpensive chemical. The straightforward sublimation of phthalic anhydride is leveraged to enable a simple and efficient separation process for polymer recycling. To liquefy phthalic anhydride, five mono-acryloyl-phthalates are synthesized to obtain stable liquid resins together with phthalic diglycidyl ester. These liquid resins undergo dual-cure reactions that comprise photopolymerization of acrylate and, subsequently, heat-mediated epoxy-acid polymerization reactions. These liquid resins exhibit moderate viscosities (2600-6400 cP @ 22 °C), fast curing, and robust thermomechanical properties (T_gs from 71 to 116 °C). It is demonstrated that hydrolysis of the dual-cured polymers completes within 2 h at 80 °C, and direct sublimation produces phthalic anhydride with 82% yield. This resin system is expected to provide a cost-competitive, highly efficient platform for recyclable FRCs.

Polymers of intrinsic microporosity (PIMs) are an emerging class of amorphous organic porous materials with solution processability, which are widely used in a multitude of fields such as gas separation, ion conduction, nanofiltration, etc. PIMs have adjustable pore structure and functional pore wall, so it can achieve selective sieving for specific substances. In order to meet the functional requirements of PIMs, two principal methods are used to synthesize functional PIMs, namely, post-modification of PIMs precursors and functionalization of monomers. A number of post-modification routes have been reported, however, the direct synthesis of functional PIMs with diverse groups still remains a challenge. The synthesis of PIMs through the acid-catalyzed polyhydroxyalkylation has been demonstrated to be an effective solution, exhibiting the advantages of wider substrates range, milder reaction conditions, and higher molecular weight. Recently, a series of functional substrates for direct synthesis of PIMs have been proposed. This article presents a review and summary of recent advances in synthesizing PIMs via acid-catalyzed polyhydroxyalkylation, and the synthesis route and structure-activity relationship are emphasized, which provides a versatile platform for the direct synthesis of functional PIMs.

Intrinsically conductive polymers have garnered a great deal of attention for use in medical and bioelectronic applications. Despite this, challenges associated with the mechanical stability, processability, and fabrication of conducting polymers have limited their utility. To circumvent these limitations, thiophene substituted 2-oxazolines (2Ox) and 2-oxazines (2Ozi) are introduced, which can be polymerized to form a thermally stable and potentially melt-processable polymers as precursors for conductive polymers. A series of such monomers are synthesized and yields above 50% are obtained for gram scale reactions. The monomers can subsequently be polymerized using standard cationic ring-opening methods to yield thiophene-bearing poly(2-oxazoline)s (POx) and poly(2-oxazine)s (POzi) with narrow to moderate dispersity. The polymers exhibit glass transition temperatures between 50 °C and 100 °C and thermal stability beyond 250 °C. Moreover, random copolymers can be produced by introducing aliphatic 2-oxazolines during polymer synthesis, which facilitates tailoring of the polymer properties and may enable new applications in melt extrusion printing or electrospinning of precursors for conducting polymer systems. Overall, a facile approach is described for the synthesis of thiophene-functionalized monomers and polymers, providing covalent integration of thiophenes that opens new avenues toward the generation of functional and stimuli-responsive biomaterials.

Electrospun fibrous materials with fine fibers and small pores are fundamental for particulate matter (PM) filtration, addressing its harmful environmental and health impacts. However, the existing electrospun fibers are still limited to their sub-micron diameters and unstable surface electrostatic effect, leading to deteriorated filtration performance after prolonged storage or wetting. Herein, the study creates nanofibrous membranes with long-time stable electrostatics by electret-enhanced electrospinning. The phase separation and polarization of the charged jet are manipulated to achieve rapid stretch and strong electret. The obtained membrane exhibits nanosized structures with fiber diameters of ≈220 nm, pore size <1 µm, as well as robust surface potential of 0.4 kV. By virtue of the synergistic effects of sieving and adsorption, the nanofibrous membrane showed a remarkable PM_0.3 filtration efficiency of 96.6% and pressure drop of 140 Pa, even reaching the N90 standard after five wetting cycles. The design of such durable membranes will offer a new sight in the functional filtration materials.

Critical issues such as leakage, degradation, and thermal response hysteresis have become the focus in the application of phase change materials (PCMs) in area such as thermal management of fabrics. The encapsulation of PCMs prepared as microcapsules using polysiloxanes, etc. as a component unit of crosslinking agents represents a highly promising avenue of research. In this work, organosilicon crosslinkers are prepared and employed for the crosslinking of poly (methyl methacrylate) (PMMA) for microencapsulation of paraffin wax in microcapsule phase change materials (mPCMs). The results showed that increasing the degree of crosslinking helps to improve the performance of mPCMs by smoothing the shell surface, but excessive crosslinking leads to flocculation, which reduces its performance. The mPCMs produced with 10% wt crosslinking agent gave the highest performance with encapsulation efficiency, melting enthalpy and crystallization enthalpy of 81.3%, 285.0 J g^-1 and 253.1 J g^-1, respectively. The obtained mPCMs are also combined with epoxy resin and fabrics to form composite materials. Notably, the polysiloxane-modified mPCMs permit epoxy resins to achieve a maximum temperature reduction of 25 °C. By adjusting the mass ratio of organosilicon crosslinkers, the obtained mPCMs enable textiles to reach a maximum temperature reduction of 17 °C while maintaining satisfactory air permeability.

Back Cover: This cover illustrates the pivotal role of water in creating a dynamic link between the hydroxypropyl cellulose polymer and organic solvents in gel polymer electrolytes. The innovative use of water as both a plasticizer and cosolvent enhances the performance of dye-sensitized solar cells. More details can be found in article 2400481 by Z. L. Goh, Shahid Bashir, K. Ramesh, S. Ramesh, and co-workers.

Front Cover: The image shows micro-phase separation in β-Ocimene–Styrene and β-Myrcene-Styrene copolymers, as studied in the article 2400641 by Carmine Capacchione, Finizia Auriemma, and co-workers. The tendency of styrene and terpene-rich sequences to give heterogeneities with correlation strength extending over 10–40 nm is outlined. The complex glass transition dynamics is also evidenced by the physical aging experienced by the amorphous phase in styrene-rich copolymers.

Lignin's complex and heterogeneous molecular structure poses significant challenges for accurate molar mass determination, which is important for its utilization in industrial applications, such as biochemicals, nanoparticles, biobased binders, and biofuels. This study evaluates the potential of Taylor Dispersion Analysis (TDA) for measuring lignin size and compares it with size-exclusion chromatography (SEC) and diffusion-ordered spectroscopy (DOSY) NMR. Using dual Gaussian fitting, flow-induced dispersion analysis (FIDA), a TDA-based method, successfully determined the average hydrodynamic radii of multiple species in solvent-fractionated soda grass lignin samples, producing results consistent with DOSY. Molar mass calibration enabled comparisons between FIDA and SEC, revealing similar relative differences across lignin fractions. FIDA offers advantages such as rapid analysis and absence of stationary phase interactions, however its accuracy is limited by the variability of lignin fluorescence. Addressing these limitations will be critical for advancing FIDA as a method for lignin size estimation.

A novel PLGA-inspired NP polymerization technique is presented, which allows the formation of NPs via the cross-linking of precisely sequenced short oligolactoglycolic acid dimethacrylates (OLGADMAs). Following the synthesis of a range of OLGADMAs, a library of NPs via this rapid and surfactant-free nanopolymerization method is successfully generated, which permits the simultaneous NP formation and encapsulation of drugs such as dexamethasone. The results indicate that NPs produced through this nanopolymerization technique with precisely controlled sequences exhibit heightened stability compared to conventionally sequenced and non-sequence controlled PLGA, as evidenced by minimal pH changes over five weeks. This improved stability is attributed to simultaneous crosslinking and co-polymerization of the OLGADMAs. Moreover, the long-acting NPs demonstrate minimal cytotoxicity and uniform cellular uptake in vitro. It is concluded that the ability to precisely regulate the sequence of short PLGA-inspired monomers and employ a unique in situ nanopolymerizing reaction results in exceptionally stable NPs for sustained drug delivery and opens exciting possibilities for the development of a range of long-lasting drug delivery systems with programmable structure and function.